‫ الب بيلوجا فور ميديكال‬/ ‫مكتبة بدر‬
BIOLOGY LAB FOR MEDICAL
STUDENTS
100211650
LAB
MANUAL
Dept of Biology & Biotechnology
i
9/20
AAUJ
BIOLOGY LAB FOR MEDICAL
STUDENTS
100211650
LAB
MANUAL
ii
Biology lab for medical
students
100211650
Table of Contents
Number Laboratory
Page
1
General Instructions
1
2
The Light Microscope
4
3
Cell Structure & Function
12
4
Chemical Composition of The Cell
20
5
Enzyme Action
30
6
Cell & Membrane Transport
37
7
Cell Division
42
8
Genetics
47
9
Animal Tissue I
51
10
Animal Tissue II
61
11
Prokaryotes
66
iii
Table of Figures
Figure Laboratory
Page
Compound light microscope
5
2.2
Dissecting microscope
5
4.1
Prokaryotic cells
13
4.2
Cork cells
14
4.3
Onion Cells
15
4.4
Tomato cells
16
4.5
Plant cell
17
4.6
Animal cell
18
2.1
Image of a human epithelial (cheek) cell as seen through a compound
4.7
microscope.
19
5.1
The catalytic cycle of an enzyme
30
6.1
For water balance of living cells (Campbell)
40
6.2
Dialysis
41
7.1
Cell cycle
43
7.2
Mitosis in plants
44
7.3
Animal cell mitosis.
44
7.4
Comparison between mitosis and meiosis
45
8.1
ABO blood grouping.
48
9.1
Four types of tissues.
51
9.2
Columnar Epithelial tissue.
53
9.3
Epithelial tissue.
53
9.4
Smooth muscle.
55
9.5
Skeletal muscle.
56
9.6
Cardiac muscle
56
iv
9.7
Structure of typical neuron.
57
10.1
Areolar (loose) connective tissue
61
10.2
Adipose tissue.
62
10.3
Reticular connective tissue.
62
10.4
Dense (fibrous) connective tissue
63
10.5
Cartilage connective tissue.
64
10.6
Bone connective tissue.
65
10.7
Blood connective tissue
65
11.1
Bacterial shapes
67
11.2
Oscillatoria
69
11.3
Gloeocapsa
69
11.4
Nostoc
70
11.5
Anabaena
70
v
Lab Topic 1:
General Instructions
The first lab will teach you safety and procedures to follow when conducting
experiments.
Laboratory safety:
1. Wear a coat to protect your clothing.
2. Do not eat, drink or smoke in the lab.
3. Dangerous, toxic, and flammable chemicals should be handled with care.
4. Wash hands with soap and water whenever you use chemicals or cultures.
5. If you have long hair, tie it back during lab period.
6. Wear eye protectors and if a substance splashes into your eyes, wash them for 510 minutes with water.
7. Read labels carefully before using any substance and take only the needed
amount.
Laboratory instructions:
1. Before each laboratory period, read over the exercises to be done and plan your
work carefully.
2. Do not miss any lab. In case of sickness, a valid excuse should be presented to the
lab instructor within three days.
3. Be on time for lab. The first part of lab will be used to introduce the material of
the lab and give quizzes. Quizzes will test your preparation for the current lab and
your understanding of materials covered in previous lab.
4. Scientific drawings and illustrations will be asked for in many labs. They should
be accurate and neat. The following guidelines should be followed:
a. Make drawings during the lab period.
1
b. Drawings should reflect relationships of biological components and
show important details. It is often useful to make an overview drawing
and then enlarge a small portion of the specimen to show the details.
c. The size of the drawing should be reasonable, so that the components
appear clear.
d. Every drawing should have a title. The components of the drawing
should be identified. This is done by drawing a straight line from the
end of the structure outward. The name of the structure should be
written at the end of this line. Avoid crossing of lines, and do not put
arrows at end of lines.
e. Drawings should be done with a 2H pencil.
5. Discard used chemicals and materials into appropriately labeled containers. Some
chemicals can be washed down a sink.
6. Report any accidents such as cuts, burns and spills to your instructor.
7. Leave your laboratory desk clean. Put papers, materials, used slides and cover
slips into appropriate waste containers.
Preparing a Laboratory Report:
The general format for lab reports is that they be divided into introduction, materials
and methods, results, discussion and conclusion according to the format which
follows in the next page.
2
The format that you should follow:
Date
Student Name
Student ID
Title of Report:
Introduction
a. Background information
b. Purpose
c. Hypothesis
Results
a. Graph or table
b. Description of data
c. Answer the questions found in the procedure
Discussion
a. Support hypothesis
b. Explanation
c. Significance of the results
Conclusion
Questions
Answers the questions that you find at the end of each lab
3
Lab Topic 2:
The Light Microscope
Objectives:
At the end of this Lab, you should able to:
1- Carry a microscope and place it correctly on your lab desk.
2- Recognize and give the function of the parts of a compound and dissecting
microscope.
3- Use the microscope correctly to locate an object of interest and focus on it under
low and high magnification.
4- Prepare a wet mount.
5- View a slide under oil immersion.
6- Determine the magnification of the microscope.
Introduction:
A microscope is an instrument that contains at least one lens and is used to view a
specimen or the details in a specimen that cannot be seen with the naked eye.
Two types of microscopes are named according to the source of
illumination used:
(We will be using the compound light microscope exclusively in our lab.)
A- Compound microscope: has a minimum of two magnifying lenses (the ocular
and the objectives lenses), which gives a compound magnification of 40X1000X. Illumination is from below, and light is transmitted through the
specimen and then magnified by objective and ocular lenses. Compound
microscopes are used to study details of very small and thin specimens or thin
sections of material prepared from larger specimens.
4
Figure 2.1: Compound light microscope
B- Stereomicroscope or Dissecting Microscope: The dissecting microscope has
relatively low magnification (7X-30X), and is used for viewing and
manipulating large objects. The advantages of this microscope are: that it
shows the specimen in three dimension and can be used for viewing large or
opaque specimens. It also provides a large working distance that allows for
manipulation or dissection of a specimen.
Figure 2.2: Dissecting microscope
5
Basic Concepts of the Microscope:
1- Magnification—is a measure of how big an object looks to your eyes
compared to its real size. Magnification is usually written by a number followed
by "X", which means "times real size". For example 10X means that the object
viewed is magnified 10 times real size. For a compound microscope Total
Magnification = magnification of ocular Lens X magnification objective lenses.
2- Resolving Power (Resolution) — is the minimum distance that two points can
be separated and still be distinguished as two separate points. It determines how
well specimen detail is preserved during the magnifying process.
Parts of the Compound Light Microscope:
1-Base—also called the supporting stand, is the lower-most part of the
microscope.
2-Arm or Neck—supports the body tube and is the part you hold to carry
microscope.
3-Body tube—this part is a metallic tube, single or double, vertical or bent, which
contains two oculars at its top, and a revolving nosepiece at its bottom.
4-Stage—supports the slide that is held by a clamp, and has a hole so that the
light can shine up through the specimen (always center the specimen over the
hole).
5- Eyepiece or Ocular lens—magnifies 10 or 15 times (10X or 15X). Oculars are
often unattached, and may fall out unless the microscope is kept upright.
6- Revolving Nosepiece—this part is found at the bottom of the tube. It is a disc,
which holds the small, medium, high and oil objective lenses. It must firmly click
into position when rotated to change the objective lens.
7- Objective Lenses—magnify the object by the factor marked on the particular
lens.
Low power (4X), medium (10X), high (40X) and oil immersion lens
(100X). Objectives must always be used in the following order: low, medium,
high, oil immersion.
With the exception of the oil immersion lens, all the
objective lenses are used dry.
6
8- Condenser this lens is located under the hole of the stage and concentrates
light before it passes through the specimen.
9- Iris Diaphraghm is located below the condenser or immediately below the
stage in microscopes without a condenser. It regulates the light intensity passing
through to the stage. More light is required at higher magnification.
10- Coarse Adjustment a knob that raises and lowers the stage in order to focus
the microscope. Do not use the coarse adjustment knob when working with high
magnification objectives.
11- Fine Adjustment a knob found adjacent to the coarse adjustment knob.
It is used for accurate focusing, and is used in conjunction with the higher
magnification objectives.
12- Source of Illumination—usually a small electric light beneath the stage that
is controlled by a push-button light switch. Sometimes a mirror is used to reflect
light from an external source into the microscope.
7
Handling the microscope:
1- Carry the microscope assigned to you with both hands, one under the base and
the other holding the microscope arm. Keep the microscope upright.
2- Remove the dust cover and clean the lenses with lens paper.
3- Start your microscope study by using the low power objective to get a general
idea of the slide.
To view more details, use the medium and the high power
objective lenses.
* The lens is sitting in the right position if you hear a "tick" when turning the
nosepiece.
4- Do not use the high power and oil immersion lenses unless the object is
covered with a cover slip.
5- Avoid getting water or other materials on the microscope. Also avoid touching
the ocular and objective lenses with your fingers. Clean up spills immediately
and clean lenses regularly with lens paper.
6- When finished with the microscope, remove the slide from the stage, make sure
that the low power lens is in the upright position, cover it and store in the cabinet.
7- If any part of your microscope is damaged, report to your instructor. Do not try
to repair any damage by yourself.
Viewing a Prepared Slide:
*****Ask your instructor to give you a prepared slide*****
1- Turn the microscope light on.
Click the lowest power objective lens into
position.
2- Use the coarse adjustment to lower the stage as far as possible, place the slide
on the stage, move it until the specimen lies over the hole of the stage.
3- Open the iris diaphragm, and look into the ocular lens.
4- Move the coarse adjustment knob up and down until you see the specimen.
5- Rotate the nosepiece to the medium power objective lens and then to high
power focusing the specimen details using the fine adjustment knob.
6- Draw the image of the specimen at 40X, 100X and 400X, ask your instructor
to help you labeling your drawings.
* As the magnification increases, the field of view, or the area you are able to see
at one time decreases.
8
To use the oil immersion lens follow the above five steps and then:
1- Move the high power lens away from the slide, and then place a drop of cedar
wood oil in the center of the cover slip and over the specimen.
2- Put the oil immersion into position and refocus using the fine adjustment only
3- Draw the image of the specimen and label it.
4- When finished, move the immersion lens away, but do not put any other lens into
position.
5- Lower the stage with the coarse adjustment and remove the slide and wipe off all
the oil using a microscopic solution on a clean lens paper.
Preparing a Wet Mount:
Wet mounts are used to study fresh materials. They are temporary slides used
for observing color, movement, and behavior that cannot be observed on dead and
stained material. The wet mount can be prepared by following these steps:
******Follow the steps to prepare your wet mount*******
1- Ask your instructor to give you a clean slide, cover slip, and letter "e".
2- Clean a microscope slide and a cover slip very well, and make sure that the
lenses are clean.
3- Place a single drop of water on the slide.
4- Place a small piece of newspaper that has the letter "e” on the center of the
slide.
5- Hold a clean cover slip, and place its edge adjacent to the drop of water, at an
angle of 45 degrees. Lower the cover slip slowly avoiding air bubbles formation.
6- Lower the cover slip so that it covers the piece of newspaper.
7- Look at the letter e with your naked eye and then view it through the
microscope.
8- Prepare another wet mount using pond water (take the drop from the bottom of
the container).
9
Staining specimens:
Lugol's iodine (IKI), methylene blue, or crystal violet may be added to specimens in
order to increase contrast. The stain can be directly added to the water when first
preparing the slide or it can be added later, after first viewing the specimen without
the stain. Add a drop of the stain along one edge of the coverslip. Placing a piece of
paper towel along the opposite edge of the coverslip will help draw the stain under the
cover slip. CAUTION: The above dyes will stain skin and clothing. They are also
harmful if ingested.
Technique for Adding a Stain when making a Wet Mount
Dissecting or Stereoscope Microscope:
Your instructor will show you how to use this microscope to view a large specimen.
Compare the image of this microscope with the image of the compound microscope.
Questions:
1- What is the magnification of an object viewed with a 10X, 40X and 100X oil
immersion, and a 10X ocular lens?
2- Why are clean glass slides and thin specimens used with the compound light
microscope?
3- Why are cover slips used to cover the specimen mounts on microscope slides?
4- A virus is 50 nm in size, would you recommend using a dissecting microscope,
compound light microscope, or an electron microscope to see it? Why?)
5-Why do you use e in your first experiment with microscope? not E
10
Biology for Medical Students
Title of Report: ………………………………………
Date /section #
Student Name: ....................................
Objectives:…………………………………………………………………………………..
………………………………………………………………………………………………….
Data and results:
Draw the letter e as you see under the microscope
4x
10x
40x
Questions:Q1) What is the magnification of an object viewed with a 10X, 40X and 100X
oil immersion, and a 10X ocular lens?
Q2) Why are clean glass slides and thin specimens used with the compound
light microscope?
Q3) Why are cover slips used to cover the specimen mounts on microscope
slides?
Q4)Why do you use e in your first experiment with microscope? not E
11
Lab Topic 3:
Cell Structure and Function
Objectives
After this laboratory you should be able to:
1- Describe similarities and differences between prokaryotic and eukaryotic cells.
2- Identify the various cell organelles and state their functions.
3- Distinguish between plant and animal cells.
Introduction:
The cell is the structural and functional unit of all living organisms. Although
cells vary in size, morphology and function, they all have three structural features:
plasma membrane, DNA and cytoplasm. Because of the small size of cells and
cellular organelles, microscopes are necessary for their study.
You have had the
opportunity to observe cells using the light microscope. The electron microscope has
enabled scientists to study organelles and determine the fine structure of cells. The
models of plant and animal cells available in the laboratory are based on electron
microscope data.
There are two main types of cells: prokaryotic and eukaryotic. Eukaryotic cells
have a membrane-bound nucleus, whereas prokaryotic cells do not have such a
nucleus. Plant and animal cells are eukaryotic. Both plant and animal cells contain
small bodies called organelles. Each organelle has a particular structure and function.
In this lab you will study these organelles and their functions.
12
Exercise 1: Prokaryotic Cells:
Prokaryotic cells lack a nucleus or other internal cell organelles and are generally very
small. Both bacteria and cyanobacteria have a prokaryotic cell.
Figure 4.1: prokaryotic cells
Procedure:
1- Study prepared slides of bacteria and cyanobacteria.
2- Draw and label a few cells from each group.
13
Exercise 2: Eukaryotic Cells:
I. Plant cells:
****Cork Cells****
Procedure:
1- Hold a cork stopper with your left hand and cut a very thin slice with a sharp
blade. The thinner the slice, the clearer the cells look.
2- Place the slice on a clean slide, and prepare a wet mount.
3- Study the wet mount at 10X and 40X magnifications.
4- Draw a few cells and answer the following questions:
Figure 4.2 Cork cells
Questions:
1. Do these cells have a similar shape and size?
2. Are these cells alive or dead?
14
****Onion Cells****
Procedure:
1- Cut an onion into smaller parts. Note that the onion is composed of layers of
succulent leaves.
2- Pick up a section of one of these leaves and hold it so that its concave side faces
you. Hold the two edges of the leaf and move them backwards to divide the leaf
into two parts. Note that a thin transparent layer covers the leaf. This layer is
called the epidermis.
3- Peel off a piece of the epidermis and place it on a clean slide. Add a drop of
water and a cover slip to prepare a wet mount.
4. Study the wet mount under low and medium magnifications.
5. At the right edge of the cover slip add a drop of methylene blue. Remove
excess stain by placing a piece of filter paper at the left edge of the cover slip.
6. Study the stained onion cells at 10X and 40X magnifications.
7. Draw a few cells, label and describe the function of the cell wall, cell
membrane, cytoplasm and nucleus.
Figure 4.3: Onion Cells
15
****Tomato cells****
Procedure:
1- Prepare a wet mount of tomato tissue by placing a small portion of the interior
tissue on a clean slide. Press gently on the cover slip to help spread the tissue into
a thin layer.
2- Study the slide with small and medium objective lenses.
3- Draw a few cells labeling the nucleus, cytoplasm, cell wall and chloroplasts.
Figure 4.4: Tomato cells
A. What is the function of chromoplasts?
16
Figure 4.5: Structure of Plant cell
Table 2: Comparison of structures between animal and plant cells
Typical animal cell



Organelles










Typical plant cell
Nucleus
Nucleolus (within nucleus)
Rough endoplasmic reticulum
(ER)
Smooth ER
Ribosomes
Cytoskeleton
Golgi apparatus
Cytoplasm
Mitochondria
Vesicles
Lysosomes
Centrosome
Centrioles
17












Nucleus
Nucleolus (within nucleus)
Rough ER
Smooth ER
Ribosomes
Cytoskeleton
Golgi apparatus (dictiosomes)
Cytoplasm
Mitochondria
Plastids and its derivatives
Vacuole(s)
Cell wall
II. Animal Cells:
Figure 4.6: Animal cell
***Epithelial Cells
The cells lining the mucous membranes of your mouth are easily sloughed off. They
are called squamous epithelial cells.
1- Using a clean toothpick, scrape the inside of your cheek gently.
2- Prepare a wet mount by placing the scrapings into a drop of water, mix and
add a drop of methylene blue.
3- Add a cover slip, and study under low, medium and high power objective
lenses.
4- Draw a few cells labeling the cell membrane, cytoplasm, and nucleus.
A- Do these cells have cell walls?
B- Do these cells have nucleoli?
18
1- Study a model of an animal cell and identify the organelles.
Figure 4.7: Image of a human epithelial (cheek) cell as seen through a compound
microscope.
Questions:
1. Are there any bacteria made of more than one cell?
2. Define cell and organelles.
3. List the differences between prokaryotic and eukaryotic cells..
4. List the differences between plant and animal cells.
19
Chemical Composition of Cells
Lab Topic 4:
Objectives:
At the end of this lab you should be able to:
1- Identify sugars, starch, lipids, proteins and vitamins.
2- Explain the fundamentals in testing for proteins, lipids, carbohydrates and
vitamins.
3- Distinguish positive tests from negative ones.
Introduction:
Living organisms consist of organic compounds that contain carbon atoms
covalently bonded to oxygen, hydrogen, nitrogen, sulfur or phosphorus and are
grouped in the categories proteins, carbohydrates, lipids and nucleic acids. Large
organic molecules are often polymers consisting of small molecules (monomers)
joined in a set sequence. Proteins are polymers of amino acids. Starch is a polymer of
glucose. Fats and oils are not polymers, but contain glycerol and fatty acids.
Various chemical reagents will be used to test for the presence of these
molecules. Most often, the result of the test is based on the presence or absence of a
color change. If a color change is observed, the test is positive, indicating that a
particular molecule is present. If color change is not observed, the test is
negative, and the molecule is not present.
In the experimental procedures you perform, you will need to include distilled water
sample, which is known as a control. The control sample will go through all the steps
of the experiment and give a negative test result, so you will be able to distinguish the
difference between a positive and a negative result.
20
Exercise 1: Carbohydrates:
Carbohydrates comprise a wide variety of monomers and polymers, and no single test
can be used as a marker for all of them. You will conduct two tests specific for two
important classes of carbohydrates.
A- Benedict Test for Reducing Sugars:
Carbohydrates are classified as reducing and non-reducing sugars. The reducing
sugars contain free aldehyde or free ketone groups, which are present in all
monosaccharides and many disaccharides. The non-reducing sugars have aldehyde or
ketone groups either bound to other groups or are modified. Benedict’s reagent
(copper sulfate in sodium hydroxide solution) oxidizes aldehyde or ketone groups by
reducing copper from Cu++ to Cu+ forming a red precipitate, Cu2O. Besides the
presence of reducing sugar, the test shows the amount of reducing sugar present in the
solution. A reaction with a small amount of reducing sugar turns the solution green.
A solution with a large amount of reducing sugar will give red-orange color.
Chemical reaction between reducing sugar and Benedict reagent:
Glucose + CuSo4 → Gluconic acid + Cu2O
(red ppt)
1. Reducing sugar
Procedure:
1- Label four clean tubes from (A to D) and place 1ml of each of the following
solutions in the corresponding test tube:
A. 5% glucose
B. 2% starch
C. Potato juice
D. Distilled water.
** Always shakes the starch solution before use.
2- Add 1ml (an equal amount) of Benedict’s solution to each tube.
3- Place the tubes in a boiling water bath for 3 minutes.
4- Record your results. Note the formation of precipitate and any color changes.
Report the results regarding the presence or absence of reducing sugar in table.
Tube
Substances
Reagent
Result
Conclusion
A
5% glucose
Benedict
Positive – color change
Reducing sugar
21
2. Non reducing sugar
Sucrose is a non reducing sugar and it will give a negative result from ordinary
Benedict's test, to see if it can be breakdown into glucose and fructose monomers
(reducing sugars) by acid hydrolysis (HCL).
Procedure:
1. Label two clean tubes (A and B)
2. Add 1 ml of 5% sucrose to the test tubes A & B
3. Add 10 drops of concentrated HCl to tube B.
4. Boil only tube B for 5 minutes at 100 °C.
1ml Sucrose5%
1ml Sucrose 5%
+HCL(10 drops)
A
B
5. Add 10 drops of 10% NaOH to neutralize HCL
6. Add 1ml of Benedict’s solution to both tubes
and boil for 2minutes.
a. What do you observe?
b. Explain your results?
B- Lugol's Test (IKI) For Starch (Iodine Test):
The test is used to distinguish starch from Mono-, di-, and other polysaccharides.
Starch is a polymer of glucose in which the chains are coiled up in a particular way so
it can interact with iodine molecules in Lugol's solution to give a distinctive blueblack color. Other polymers even those of glucose, lack the precise coiled structure
of starch and do not give the blue color. A violet-brown to red-brown color is given
by cellulose, and a red color is given by glycogen.
Procedure:
1- Label four test tubes from (A to D) and place 1ml of each of the following
solutions in the corresponding test tube:
A. 5% glucose
B. Potato juice
C. 2% starch
D. Distilled water
2- Add 5 drops of Lugol's solution to each tube, and then shake the tubes.
3- Record your results in a table
Tube
Substances
Reagent
Result
Conclusion
A
5% glucose
Lugol's
Negative-no color change
No starch present
22
Exercise 2: lipids:
Lipids are a heterogeneous group of compounds that are insoluble in water but
are soluble in so called fat solvents such as ether, acetone, and alcohol. Fats and oils
are two important types of lipids found in living things. Chemically, both are similar,
being composed of the same two subunits: glycerol and either saturated or unsaturated
fatty acids.
A. Visual Test
Procedure:
1- Place one drop of oil in a Petri dish half filled with tap water. Observe what
happens at the surface of the water and record your observations.
2. Interpret your results in terms of:
A- The ability or inability of oil molecules to form hydrogen bonds with water.
B- The relative densities of oil and water.
23
C. Emulsification:
Emulsification is the mechanical breakdown and dispersal of large globules into
smaller droplets. This process is important to some vital processes like fat digestion.
An emulsifier contains molecules with polar and nonpolar ends. When the nonpolar
ends are attached to the nonpolar fat, the polar ends are exposed. Since the polar ends
are soluble in water, the fat is dispersed. For example bile salts that secreted from the
liver are composed of the salts of 4 different kinds of free bile acids
(cholic,deoxycholic,chemodeoxycholic,and lithocholic acids)→faciltate formation of
micelles→processing of dietary fat.
Procedure:
2- Label 2 Petri dishes A&B and then add 10 drops of olive oil+ 5ml of
distilled water
3- Then add 10 drops of Bile salts to B.
2- Shake vigorously; let it settle for 5 minutes.
4- Record your observations and explain the difference.
5 ml distilled
water+10
drops oil A
5ml distilled
water+10
drops oil+10
drops bile salt
B
control
24
Exercise 3: Proteins:
Proteins are a diverse class of biological molecules that are the key substances
in the structural and physiological functioning of living things. Proteins are polymers
of amino acids in which the carboxyl group of one amino acid links with the amino
group of the next amino acid in a covalent peptide bond.
A. Ninhydrin Test:
Ninhydrin is a reagent that reacts with free amino groups (-NH2) of an amino acid or a
protein. It turns blue-purple when applied to a protein-containing substance, except
with proline, it gives a yellow color.
Caution: Ninhydrin is a toxic substance, avoid inhaling the fumes, and do not let
the solution touch your skin or clothing.
Figure 3.1: Ninhydrin reaction with amino acid
Procedure:
1- Label four test tubes (A to D).
2- Place 1ml of each of the following solutions in the corresponding test tubes.
A. Lysine
B. 5% glucose
C. 2% starch
E. Egg albumin
D. Distilled water
3- Add 1ml of ninhydrin solution to each test tube.
4- Place the test tubes in boiling water for 3-5 minutes.
5- Record and interpret your results.
Ninhydrin
1ml
Solution
1ml
25
Tube
Substances
Reagent
Result
Conclusion
A
Lysine
Ninhydrin
Positive-color change
Amino acid
presence
B. Biuret Test:
Biuret reagent (blue color) contains a strong solution of sodium or potassium
hydroxide (NaOH or KOH) and a very small amount of very dilute copper sulfate
(CuSO4) solution. The reagent changes color in the presence of a protein and peptides,
because the amino group complexes with the copper ions.
A violet color is indicative of whole proteins, whereas pink or rose color is
indicative of polypeptides.
Procedure:
1- Label three test tubes (A to C). Place 1ml of the following solutions in
the corresponding tubes.
A. Lysine
B. Egg albumin solution
C. Distilled water.
2- Make each solution alkaline by adding 1ml of 10% sodium hydroxide
(NaOH).
3- Add (5-7) drops of 1% copper sulfate solution to each tube, and mix
well.
6- Note the color change and record your results.
CUSO4
5-7
drops
NaOH
1ml
Solution
1ml
Exercise 4: Vitamins:
Vitamins are complex chemical compounds of high molecular weight that are
essential to normal growth and health maintenance. In this exercise you will test for
vitamin C (ascorbic acid), which is found in high concentrations in the citrus fruits.
The indicator you will use is indophenol. The indicator is blue in color but fades in
the presence of ascorbic acid.
26
Vitamin C+ Indophenols (drop by drop) →Blue color fading
Procedure:
1- In three test tubes put 10 drops of 0.1 % indophenols solution.
2- Add drops of lemon, orange, and tomato juices to the tubes (count the
drops) until the color changes from blue to pink or colorless or to the color
of the juice.
3- Count the drops and record your results.
??? drops of different juices↓↓↓
10 drops of indophenols
Questions:
1- What is the purpose of the test tube containing distilled water in each test?
2- Why is glucose called a reducing sugar?
3- Name the reagents used to detect the presence of reducing sugar, amino acids,
and protein?
27
Biology for Medical Students
Title of Report: ………………………………………
Date /section #
Student Name ....................................
Objectives:…………………………………………………………………………………..
………………………………………………………………………………………………….
Data and results:
I) Benedict test
Tube
Substances
Reagent
Result
Conclusion
A
B
C
D
Sucrose
Sucrose+HCL
II) Lugol’s test
Tube
Substances
Reagent
Result
Reagent
Result
A
B
C
D
III)Ninhydrin test
Tube
Substances
A
B
C
D
E
28
Conclusion
IIII) Biuret Test
Tube
Substances
A
B
C
V) Vitamins
Tube
Substances
A
B
C
Reagent
Result
Reagents
#of drops
Conclusion
conclusion
VI) Lipids test
A) Visual test:
As you observe in the visual test answer the following:
1. The ability or inability of oil molecules to form hydrogen bonds with water.
………………………………………….
2.The relative densities of oil and water.
……………………………………………………………..
B) Emulsification
Record your result
………………………………………………….
Questions:
1.What is the purpose of the test tube containing distilled water in each test?
…………………………………………………………………..
2.Why is glucose called a reducing sugar?
……………………………………………………………………
3.Name the reagents used to detect the presence of reducing sugar, amino acids,
and proteins?
………………………………………………………………………
29
Lab Topic 5:
Enzyme Action
Objectives:
At the end of this lab you should be able to:
1- Define enzyme, pH and denaturation.
2- Describe how temperature, pH, enzyme and substrate concentrations affect
the reaction rate.
Introduction:
Many but not all enzymes are proteins, because some RNA function as enzymes
(Ribozymes). These molecules function as biological catalysts. A catalyst is a
substance that lowers the amount of energy needed for a chemical reaction to occur. It
does not cause the reaction but speeds up the reaction rate and it’s not consumed
during the reaction. In enzyme-catalyzed reactions the reactant is called the substrate.
During the reaction, substrates combine with special regions of the enzyme called
active sites to form a temporary enzyme-substrate complex.
Substrate + Enzyme → Enzyme-Substrate Complex → Products + Enzyme
Figure: The catalytic cycle of an enzyme
30
Each enzyme is specific for a certain reaction. The specificity is a result of a unique
amino acid sequence, which causes it to have a unique three-dimensional structure. Any
physical or chemical factor that leads to a change in the shape or chemistry of the active site
in the enzyme will interfere with the activity and efficiency of the enzyme. If the change is
large enough, the enzyme will no longer function. There are several factors that are
especially important in determining the enzyme activity, and these are regulated both in the
living organisms and in laboratory experiments to give optimum enzyme activity. Some of
these factors include salt concentration, temperature, pH, concentration of the enzyme and its
substrate. Increased temperature may lead to permanent “denaturation” of the enzyme.
In this lab you will study the activity of three enzymes: Catecholase, alpha-amylase
which converts starch into the double sugar maltose, and catalase which decomposes
hydrogen peroxide to oxygen and water.
31
Exercise 1: The effect of Catecholase on a Cut Apple:
Catecholase or catechol oxidase is an enzyme that causes bruised fruits to turn brown by
catalyzing the reaction between catechol and oxygen. In the presence of catecholase,
catechol is oxidized to form benzoquinone and water (see the equation). Benzoquinone is
a component of chemical compounds that give bruised fruits their brown colors. When an
apple is sliced, catecholase will be released onto the white surface of the fruit and
catalyzes the removal of electrons and hydrogens from catechol. However, simple change
in the conditions can change the rate of this chemical reaction.
catecholase
Catechol + O2
Benzoquinone + H2O
Procedure:
1. Get half apples cut it into six small sections and treat them as follows:
A. Place one section in a beaker of ice.
B. Place one section in a warming oven (about 40C˚).
C. Place one section in a petri dish and cover it with lemon juice. Test the pH of
lemon juice with pH paper.
D. Place one section in a petri dish and cover it with distilled water. Test the pH of
distilled water with pH paper.
E. Place one section in a mortar and mash it to a pulp with a pestle. Place the mashed
apple in a Petri dish, and leave it on your lab disk.
F. Place one section in a Petri dish and leave it undisturbed.
2. For each of the above treatment indicates in your report, which of the factors
you changed altered the reaction rate.
3. Check the apple sections every ten minutes for the first half hour.
4. After the first half hour of frequent observation, check the apple sections
periodically until the end of the lab period. Record your results.
32
Exercise 2: Amylase Action:
In this experiment you will observe the action of the enzyme amylase on starch.
Amylase changes starch into a simpler form: the sugar maltose (disaccharide), which
is soluble in water. Amylase is present in our saliva, and begins to act on the starch in
our food while still in the mouth.
Benedict's solution is a test reagent that reacts positively with simple reducing sugars
like maltose, but will not react with starch. A positive test is observed as the
formation of a brownish-red cuprous oxide precipitate. A weaker positive test will be
yellow to orange.
Procedure:
1. Place 4 ml of the starch solution (0.5%) into a test tube, and add 1ml of the
amylase, mix well and gently.
2. Place 4 ml of the starch solution (0.1%) into a test tube, and add 1ml of distilled
water, mix well and gently.
3. Place 4 ml of water into a test tube, add 1ml of the amylase, mix well and
gently.
4. Simultaneously and immediately after mixing the contents, take 1ml at
this time (as zero time) from each tube.
5. Take another 1 ml sample after 40 minutes. Test for reducing sugars
and starch by using Benedicts and Lugol's reagents, respectively.
6. Record your results in a tabulated form.
33
At zero time
After 40 min.
34
Exercise 3: Catalase Activity:
Catalase is an enzyme found in cells particularly in liver cells.
It minimizes the
accumulation of toxic hydrogen peroxide which is a product of several reactions that
normally occur in cells:
2H2O2 + Catalase → 2H2O + O2 (bubbles)
Procedure:
1. Cut three pieces of potato. Place one piece in each of two test tubes, boil
one piece and then place it in a third tube.
2. Add 5ml of water to tube a.
3. Add 5ml of 3% H2O2 to tube b.
4. Add 5ml of 3% H2O2 to tube c.
5. Record the results and explain.
Picture. 1 : Fresh potato +H2O2→H2O+O2 (air bubbles)
35
Questions:
1. Why did you use buffer instead of distilled water to dilute the enzyme and the
substrate?
2. What do we mean by enzyme specificity?
3. Name the substrate of peptidase, sucrase and amylase?
4. Discuss the factors affecting the rate of an enzymatic reaction, showing how each
one affects the rate?
36
Lab Topic 6:
Cell and Membrane Transport
Objectives:
At the end of this lab you should be able to:
1. State the ways in which substances enter cells.
2. Define isotonic, hypotonic and hypertonic solutions.
3. Predict the effect of these solutions on animal and plant cells.
4. Distinguish between diffusion and osmosis.
Introduction:
All organisms interact with their external environment to maintain an internal
environment favorable for the existence of cells. In the process, materials pass
between the organism and its environment as well as among cells within the
organism. This flow of materials into or out of the cell is regulated by the membranes
surrounding the cells. These membranes are boundaries that the solutes must cross to
reach the cellular site where they will be utilized for the processes of life. Biological
membranes are selectively permeable allowing some substances to move easily while
completely excluding others.
Living cells are made up of 75--85 % water. Almost all substances entering and
leaving cells are dissolved in water. The substances dissolved in water are called
solutes.
The combination of a solvent such as water and dissolved solutes is a
solution.
Molecules in cells are in constant motion. This motion increases with temperature.
The motion of molecules produces a variety of effects such as diffusion, osmosis and
Brownian movement (is the presumably random moving of particles suspended in a fluid
(a liquid or a gas) resulting from their bombardment by the fast-moving atoms or
molecules in the gas or liquid). Diffusion is the movement of solute molecules from a
region of high to low concentration.
differentially permeable membrane.
Osmosis is the diffusion of water across a
Osmotic phenomena in cells are determined by
the relative concentration of solutes across membranes. The movement of water and
solutes is determined by membrane properties and solute gradients. One of the most
important functions within a living organism is to maintain osmotic homeostasis.
37
Exercise 1: Diffusion:
I. Diffusion of a Liquid in a Liquid:
Procedure:
1. Fill a small beaker with water and allow it to stand without moving for 5
minutes.
2. Use a dropper to add a drop of methylene blue to the surface of the solution as
gently as possible.
3. Watch the spreading of the dye and describe what you observe.
II. Diffusion of a Liquid in a Solid:
Procedure:
1. Obtain a screw-cap test tube filled with congealed gelatin. Add a small amount
of methylene blue to one end of the tube.
2. Place the tube in a horizontal position.
3. Watch the diffusion of the dye in the tube during the lab period.
Exercise 2: Osmosis:
I. Effect of Osmosis (Tonicity) on Plant Cells:
Procedure:
1. Effect of tonicity on potato strips
a. Cut two strips of potato, mark two test tubes 1 and 2.
b. Place one potato strip in each tube.
c. Fill tube 1 with water, and tube 2 with 10% NaCl. Make sure the potato strip
is covered with solution.
* After 1 hour observe each strip for limpness or stiffness. Explain?
II. Effect of Osmosis (Tonicity) on Animal Red Blood Cells:
A solution of 0.9% NaCl is isotonic to the red blood cells. In such a solution, cells
maintain their normal appearance. A solution greater than 0.9% NaCl is hypertonic,
and red blood cells will shrivel, a process called crenation. A solution of less than
38
0.9% NaCl is hypotonic and will cause red blood cells to swell and burst, a process
called hemolysis.
Procedure:
1. Tube 1: put 5ml DW in a test tube and add 5µl of whole blood and shake it, wait
for 5-10 minutes.
2. Tube 2: put 5ml of 0.9% NaCl and add 5µl of whole blood and shake it, wait for
5-10 minutes.
3. Tube 3: put 5ml of 10% NaCl and add 5µl of whole blood and shake it, wait for 510 minutes.
4. Prepare a wet mount from each test tube and examine under microscope and record
your results
5µl
blood
+5ml
Dw
1
↓
10µl
5µl
blood
+5ml
0.9%
Nacl
5µl
blood
+5ml
10%
2
3
1
1
1
1
10µl 1
Nacl
3
↓
3
2
10 µl
1
1
1
1
39
↓
Figure 6.1: For water balance of living cells (Campbell)
Exercise 3: Dialysis:
Dialysis is defined as the diffusion of a solute through a selective permeable
membrane. In this experiment you will separate starch from IKI using dialysis tubing.
Procedure:
1. Take 15cm long dialysis tubing & make a tight knot at one of end to form a bag.
2. Using a funnel, pour 5ml starch solution into the bag and mix.
3. Make another tight knot at the other end of the bag and trim the ends.
4. Suspend the bag in a 200ml beaker filled with distilled water and containing the
IKI. Test this sample for the starch using IKI and record your results. Which
substance was found outside the bag? Why?
40
IKI
Starch
KI
Figure 6.2: Dialysis
Questions:
1. What is the name for the movement of water across a differentially permeable
membrane?
2. What scientific term is used to refer to the appearance of plant cells in 10% NaCl?
3. Explain the following:
A. Why plant cells build up turgor pressure?
B. Why the tissue fluid surrounding human cells must be isotonic?
41
Cell Division
Lab Topic 7:
Objectives:
The following laboratory is intended to help you better visualize and understand
mitosis, meiosis and cytokinesis. At the end of this lab you should be able to:
1. Describe what happens during each of the phases of mitosis.
2. Describe what happens during the phases of meiosis.
3. List the differences between mitosis and meiosis.
Introduction:
Cell division is a fundamental process common to all living organisms and is the
mechanism by which organisms are able to grow and reproduce. In eukaryotic cells,
typical cell division is divided into mitosis and cytokinesis. Mitosis is division of the
nuclear material. Cytokinesis is division of the cytoplasm. The process results in two
cells, each of which has a complete set of cellular material from the parent, including
a complete set of chromosomes or DNA. The replication and division of the DNA
material is a continuous process, but the major events have been divided into phases
known as interphase, prophase, metaphase, anaphase and telophase. A synopsis of the
major events in each phase is presented below. In this lab, you will investigate the
process of mitosis in plants using slides of onion root tips and in animals using
whitefish embryo cells.
Phases of the Cell Cycle:
(A) . Interphase—During interphase the cell carries on normal metabolic processes.
If it has recently divided it will also proliferate organelles and cytoplasm. If the cell
is to divide again, the DNA material will replicate, and preparations will begin for the
next division event.
This part of the cell cycle is often subdivided into G1, S and G2
subdivisions.
42
Figure7.1: Cell cycle
(A).Mitotic phases
1. Prophase— during this phase the nuclear envelope and nucleolus disappear.
Distinct chromosomes become visible and are randomly arranged in the center of the
cell. Each chromosome is made of a pair of chromatids held together at the
centromere. In animal cells, the centrioles divide and move to opposite poles of the
cell. Around each centriole a number of microtubules radiate to make the aster.
2. Metaphase— a fully formed spindle composed of microtubules that stretch from
pole to pole is evident.
Each chromosome is attached to a spindle fiber at the
centromere, and all the chromosomes are lined up at the equator of the cell.
3. Anaphase— the centromeres divide, the sister chromatids separate, and a set of
chromosomes moves toward each pole.
4. Telophase— the chromosomes cluster together near the spindle poles, and new
nuclear envelopes develop around them. The nucleolus reappears, the spindle begins
to disappear, and cytokinesis occurs.
Cytokinesis—Cytokinesis refers to the division of the cytoplasm into daughter cells,
each cell surrounding one of the two daughter nuclei.
Cytokinesis occurs by the
formation of a cleavage furrow in animal cells and the formation of a cell plate in
plant cells.
43
Interphase
Prophase
Metaphase
Figure 7.2 : Plant cell mitosis
Mitosis in animals
Figure 7.3: Animal cell mitosis.
44
Anaphase
Telophase
Meiosis
Meiosis is a special form of cell division associated with sexual reproduction.
The
process consists of a reduction division of nuclear material, which occurs in two
stages. The first stage is known as Meiosis I consisting of prophase I, metaphase I,
anaphase I and telophase I.
During this division homologous chromosomes are
separated and diploid or 2n cells become haploid or 1n cells.
consists of two chromatids connected at the centromere.
Each chromosome
The second division is
known as Meiosis II and consists of prophase II, metaphase II, anaphase II and
telophase II. During this division the chromatids are separated. The end result of a
meiotic division is four cells, each of which has one-half the number of chromosomes
existing in the parent cell. In this lab you will review the events in the phases of
meiosis and compare meiosis to mitosis.
Figure 7.4: Comparison between mitosis and meiosis
45
PROCEDURE:
A. Mitosis in Plants:
Obtain a prepared microscope slide containing sections of an onion root. Study the
slide under low power magnification on a microscope and locate the sections of the
root tip. Focus on the meristematic region and increase the magnification so you can
identify the various stages of mitosis evident in these cells.
Make drawings and
notations as requested below.
B. Mitosis in Animals:
Study the phases of mitosis in the available models and on whitefish embryo slides
and make drawings of each phase. In addition to labeling the structures mentioned in
the plant mitosis instructions, include the centrioles and asters. Note: at which phase
the various structures appear and disappear.
Pay attention to when the terms
chromosome and chromatids are appropriate.
Use the models in the lab and
illustrations in your text to assist you.
C. The Phases of Meiosis:
1.
Starting with a diploid cell containing four chromosomes, draw a sequence of
diagrams illustrating the phases of meiosis I and meiosis II and accurately
representing the appearance, location and number of chromosomes in each stage.
Next to each drawing list all of the events associated with the stage you are
representing. Use models in the lab and illustrations in your text to assist you with this
exercise.
In animal life cycles the process of meiosis leads to the formation of
gametes in a process called gametogenesis.
In males, the specific term used is
spermatogenesis for the formation of sperm. In females, the term oogenesis is used
for the formation of the egg.
E. Comparison of Mitosis and Meiosis:
List the differences between mitotic cell division and meiotic cell division.
46
Lab Topic 8:
Genetics
Objectives:
1. Determine the genotypes of parents when the genotypes of children are
known.
2. Determine the genotypes of children when the genotypes of parents are
known.
Introduction
:
Genetics is the study of the mode of transmission of genes from one generation to
the next. There are two copies of each gene called alleles in every diploid cell, with
one allele on each homologous chromosome.
Today you have the opportunity to
study some characteristics which humans have and will determine your genotype
for these traits
Excersie1: Genetics of Blood Typing:
A. ABO Blood Typing: The major blood groups in humans are determined by
multiple alleles, there are three possible alleles, each individual has only two of
the three alleles determining whether they have blood type A, B, AB or O. The
table (8.1) below indicates the possible phenotypes and genotypes for ABO blood
types.
47
Genotype(s)
AA, AO
BB, BO
AB
OO
Figure 8.1: ABO blood grouping.
B. Rh blood factor
It is inherited as single pair alleles. Rh positive (Rh+) is dominant over Rh negative
(Rh-).
1. Draw three circles on a clean slide and mark them A, B, and D.
2. Place on "A" a drop of anti-A serum, on "B" a drop of anti-B serum, and on "D" a
drop of anti-D serum.
3. Clean your thumb by 70% ethanol.
4. Puncture your thumb with a sterile lancet.
5. Place one drop of anti-sera A, B, and D respectively in the three circles.
6. Use a clean toothpick for each drop of blood to mix the blood and serum drops.
7. Gently rock the slide back and forth for a thorough mixing of blood and
antiserum.
8. Examine the blood for signs of agglutinations.
9. Record your results and explain.
In hospitals they do cross matching test ,refers to the testing that is performed prior to a blood
transfusion in order to determine if the donor's blood is compatible with the blood of an intended
recipient
48
Exercise 2: Color Blindness
It is an X-linked recessive trait. The possible genotypes are:
Females
B
X X
B
B
X X
b
b
b
X X
Normal vision
Normal vision (carrier)
Males
B
Normal vision
b
Color blind
X Y
X Y
Color blind
Table 8.2 genotype and phenotype of color blindness
Determine whether you are color blind or not by looking at the chart provided.
Exercise 3: Other Human Genetics Characteristics:
1. Ability to taste PTC
PTC (phenylthiocarbamide) is an anti thyroid drug that prevents the thyroid gland
from incorporating iodine into the thyroid hormone.
It can be tasted by some
individual as being bitter or sour, while others cannot. Chew a piece of filter paper
treated with PTC and record if you taste or not. The ability to taste is dominant and
non-taster is recessive. Tasting (T) is dominant to no tasting (t).
2. Ear lobes:
Unattached earlobe (F) is dominant to attached earlobe (f). Examine your earlobes
and record your phenotype.
49
3. Curling of tongue:
Many individuals can easily roll their tongues upward to form a cylinder. The ability
of curling tongue is dominant (R) of inability (r). Record your phenotype. (Thinking
issue: Test your parents for this character! if they are non rollers and you are roller, do
you think rolling is controlled by a dominant allele???
3. Eye color and hair color are polygenic characters.
5. Hair on mid-digital segments of fingers:
The presence of hair on the mid-digital segments of fingers is genetically determined
by a dominant allele (M).
Questions:
1) Do you think that dominant characters are the most frequent? If not give examples?
2) Do you think all diseases are controlled by recessive alleles? If not give examples
50
Lab Topic 9:
Animal Tissues I
Introduction
A tissue consists of a few types of closely associated cells that are adapted to
carry out specific functions. The study of normal tissues is called histology. Animal
tissues are classified as epithelial, connective, muscular, and nervous. Each kind of
tissue is composed of cells with a characteristic size, shape and arrangement. In this
lab you will study prepared slides of various tissues. Make careful drawings
representing what you observe under the microscope. Your drawing should be of
sufficient quality that it would remind you about the particular tissue. Label cells and
structures and next to each drawing list the function for the tissue and an example of a
location in the body where it occurs.
Figure 9.1: four types of tissues.
51
Epithelial tissue
In biology and dermatology, epithelium is a tissue composed of a layer of cells. In humans, it is
one of four primary body tissues. Epithelium lines both the outside (skin) and the inside
cavities and lumen of bodies. The outermost layer of our skin is composed of dead stratified
squamous epithelial cells, as are the mucous membranes lining the inside of mouths and body
cavities. Other epithelial cells line the insides of the lungs, the gastrointestinal tract, the
reproductive and urinary tracts, and make up the exocrine and endocrine glands.
Functions of epithelial cells include secretion, absorption, protection, transcellular transport,
sensation detection, and selective permeability. Endothelium (the inner lining of blood
vessels) is a specialized form of epithelium.
Classification:
Epithelial cells are classified by the following three factors
1. Shape
2. Stratification
3. Specializations
Shape
Squamous: Squamous cells are flat cells with an irregular flattened shape. A one-cell
layer of simple squamous epithelium forms the alveoli of the respiratory membrane,
and the endothelium of capillaries, and is a minimal barrier to diffusion. Other places
where squamous cells can be found include the filtration tubules of the kidneys, and
the major cavities of the body. These cells are relatively inactive metabolically, and
are associated with the diffusion of water, electrolytes, and other substances.
Cuboidal: As the name suggests, these cells have a shape similar to a cube, meaning
its width is the same size as its height. The nuclei of these cells are usually located in
the center.
Columnar: These cells are taller than they are wide. Simple columnar epithelium is
made up of a single layer of cells that are longer than they are wide. The nucleus is
also closer to the base of the cell. The small intestine is a tubular organ lined with this
type of tissue. Unicellular glands called goblet cells are scattered throughout the
simple columnar epithelial cells and secrete mucus. The free surface of the columnar
cell has tiny hairlike projections called microvilli. They increase the surface area for
absorption.
52
Figure 9.2: Columnar epithelial tissue.
Transitional: This is a specialized type of epithelium found lining organs that can
stretch, such as the urothelium that lines the bladder and ureter of mammals. Since the
cells can slide over each other, the appearance of this epithelium depends on whether
the organ is distended or contracted: if distended, it appears as if there are only a few
layers; when contracted, it appears as if there are several layers.
Stratification
 Simple: There is a single layer of cells.
 Stratified: More than one layer of cells. The superficial layer is used to
classify the layer. Only one layer touches the basal lamina. Stratified cells can
usually withstand large amounts of stress.
 Pseudostratified with cilia: This is used mainly in one type of classification
(pseudostratified columnar epithelium). There is only a single layer of cells,
but the position of the nuclei gives the impression that it is stratified. If a
specimen looks stratified, but you can identify cilia, the specimen is
pseudostratified ciliated epithelium since stratified epithelium cannot have
cilia. A cell that contains hairs will be around ten times stronger than a regular
cell
Figure 9.3: Epithelial tissue
53
Specializations:
 Keratinized cells contain keratin (a cytoskeletal protein). While keratinized
epithelium occurs mainly in the skin, it is also found in the mouth and nose,
providing a tough, impermeable barrier.
 Ciliated cells have apical plasma membrane extensions composed of
microtubules capable of beating rhythmically to move mucus or other
substances through a duct. Cilia are common in the respiratory system and the
lining
of
the
oviduct
54
Muscle Tissue
Muscle cells contain contractile fibers, and the contraction of these fibers accounts for
the movement associated with animals, food movement in gut, and heat production.
There are three types of vertebrate muscle tissue: skeletal, smooth, and cardiac.
Smooth Muscle
Smooth muscle is involuntary.
The gut is surrounded by smooth muscle that pushes food through the digestive tract.
It surrounds the blood vessels where it controls the distribution of blood. For example,
after meals, the blood vessels of the gut are opened while many of those in the
skeletal muscles contract.
The ends of the cells are tapered.
Figure 9.4: Smooth muscle.
55
Skeletal Muscle
Skeletal muscles are voluntary. The cells are very long, extending the length of the
muscle. They are multinucleate, and striated (striped)
Figure 9.5: Skeletal muscle.
Cardiac Muscle
Cardiac muscle is found in the heart and is involuntary.
It is striated and branched.
Figure 9.6: Cardiac muscle.
56
Nervous Tissue
Nervous tissue responds to stimuli and transmits impulses from one body part to
another. Nervous tissue is composed of specialized cells called neurons and a group of
supporting cells called glial cells. The neuron cell is specialized for conduction of
nerve impulses, and each cell has a cell body, a number of processes called dendrites,
and one axon.
Figure 9.7: Structure of typical neuron.
57
Epithelial Tissue
Simple
Stratified
Squamous
Cuboidalal
Squamous
Cuboidal
al
lungs
Blood
vessels
Gland
s
Columnar
Columnar
Skin + esophagus
Intestine
s
Ducts
of sweat
Salivary
&mammary
glands
Epiglottis & Urethra
Kidneys
Body
Cavities
Filtration Tubules
of kidneys
Transitional
Organs that
stretch
Pseudo stratified
lining
ureter
bladder
58
Nasal cavity
Muscular Tissue
Smooth
Surrounds gut
&blood vessels
vvesseles
Cells are
tapered
involuntary
Skeletal
Cells ,long,
striated&
multinucleated
Surrounds
muscles
voluntary
Cardiac
Striated&
branched
In heart
involuntary
Nervous Tissue
Neurons
Glial cells
59
Connective Tissue
loose
Dense
Bone
Blood
cartilage
Irregular
Regular
Areolar
Adipose
eeeeeee
Reticular
Tendons
Legments
Questions:-
1. What are the main types of animal tissue?
2. What are epithelial tissues? What is their general function and how is that function
associated to the features of the tissue?
60
Lab Topic 10:
Animal Tissues II
Connective Tissue
The cells of connective tissue are separated by non-living material called matrix.
Connective tissue binds and supports body parts, protects, fills spaces, stores fat (for
energy), and transports materials.
Structure of Loose and Dense Connective Tissue
Loose connective tissue and dense connective tissue contain three kinds of fibers.
Collagen fibers provide strength and flexibility. Collagen is the most abundant protein
in animal bodies. Elastic fibers provide elasticity. When stretched, they return to their
original shape. Reticular fibers are small and branched. They provide a support
framework for organs such as the liver and lymph nodes.
The cells of loose and dense connective tissue are called fibroblasts. They produce the
fibers and nonliving matrix material. Macrophages are cells specialized for
phagocytizing foreign materials, bacteria, and cleaning up debris.
Loose Connective Tissue
Loose connective tissue includes areolar, adipose, and reticular connective tissue.
Areolar Connective Tissue:
The fibroblasts (cells) of areolar connective tissue are separated by a nonliving,
jellylike matrix. The tissue contains collagen fibers for flexibility and strength, and
numerous elastic fibers that enable it to be stretched.
Figure 10.1: Areolar connective tissue
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Areolar connective tissue is found in the skin and in most internal organs of
vertebrates, where it allows the organs to expand; it also forms a protective covering
for muscles, blood vessels, and nerves.
Adipose tissue:
This type of loose connective tissue. It has reduced matrix material and contains
enlarged fibroblasts (cells) that store fat. Adipose tissue functions to store energy,
insulate, and provide padding, especially in the skin and around the kidneys and
heart. The nucleus is pushed to on side because of fat droplets. If the fat is not
stained in your slide, the cells in adipose tissue will look like "ghost" cells.
Figure 10.2: Adipose tissue.
Reticular Connective Tissue
Reticular connective tissue contains an abundance of reticular fibers. It provides a
supporting framework for organs such as the lymph nodes, spleen, and liver.
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Figure 10.3: Reticular connective tissue.
Dense (Fibrous) Connective Tissue:
The collagen fibers of dense connective tissue are more closely packed than those of
loose connective tissue.
Figure 10.4.A: Dense (fibrous) connective tissue
Regular dense connective tissue contains collagen fibers oriented in one direction to
provide strength in that direction. It is found in tendons and ligaments. Tendons
connect muscle to bone; ligaments connect bone to bone.
Irregular dense connective tissue (Fig 10.5) contains collagen fibers oriented in
many different directions. It is found in the deep layers of the skin and the tough
capsules that surround many of the organs such as the kidneys, adrenal glands, nerves,
bones, and the covering of muscles. It provides support and strength.
Figure10.4.B: Irregular dense connective tissue
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Cartilage:
It contains collagen and elastic fibers. Cells called chondrocytes are located in spaces
called lacunae. A flexible matrix containing chondroition sulfate and fibers separates
the lacunae. It is resilient; it does not stretch and can resist compression. It is also
flexible but maintains its shape.
It is found in the ends of bones where it prevents friction within the joints. In the nose,
external ear, and the walls of the trachea it functions to support the softer tissues.
The fetal skeleton of vertebrate animals is composed of cartilage before bone forms.
The skeleton of cartilaginous fish is composed of cartilage.
Figure 10.5: Cartilage connective tissue.
Bone:
Bone forms when calcium salts are deposited around protein fibers. The calcium salts
provide rigidity while the fibers provide elasticity and strength. Its flexibility comes
from a collagen matrix which prevents bone from becoming brittle.
Bone tissue is
composed of osteocytes (bone cells) trapped within lacunae.
Osteocytes
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communicate with one another and with capillaries by canaliculi, they are arranged in
concentric layers called lamellae around a central canal called the Haversian canal.
Figure 10.6: Bone connective tissue.
Blood:
Blood is a connective tissue: it is composed of cells in liquid matrix, but in this type
of connective tissue the matrix is liquid and is called plasma. Blood contains two
types of cells: red blood cells (erythrocytes) & white blood cells (leukocytes). It also
contains clusters of cell fragments called platelets or thrombocytes.
Figure 10.7: Human Blood
1. What is connective tissue proper?
2. What are the three types of protein fibers of the connective tissue proper?
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Lab Topic 11:
Prokaryotic Life
Objectives:
1. Describe the characteristics of prokaryotic organisms.
2. Define characteristics of bacteria and archaea.
3. Distinguish gram-positive from gram-negative bacteria.
Introduction:
Prokaryotic organisms have traditionally been grouped in the Kingdom Monera.
More recent thinking has separated prokaryotes into two groups based on unique
ribosomal RNA sequences.
The most ancient organisms are classified in the
Kingdom Archaebacteria or Domain Archaea. These organisms are typically
anaerobic and inhabit extreme environments like hot springs and saline ponds. The
more familiar bacteria, including cyanobacteria (formerly called blue-green algae),
are classified as Kingdom Eubacteria or Domain Bacteria.
Bacteria are the simplest and most primitive organisms. They have prokaryotic
cells, and reproduction is asexual by fission. Most bacteria are saprobic, meaning that
they send out digestive enzymes into the environment and thereafter take up the
resulting nutrient molecules. Some bacteria are parasitic and cause diseases, such as
strep throat. Other bacteria are photosynthetic or chemosynthetic and therefore are
able to make organic molecules utilizing inorganic molecules. Bacteria are small and
their internal structure is not visible in the light microscope.
For this reason their
identification depends on:
1. Shape.
2. Response to stain such as whether the strain is gram positive or gram negative.
3. Arrangement in groups.
4. Appearance in colonies on culture plates.
5. Metabolic reactions.
Cyanobacteria are photosynthetic. They contain chlorophyll, but the green color often
is masked by other pigments. In fact, some cyanobacteria are red, brown, or even
black.
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Exercise 1: Bacteria:
Procedure:
Bacteria can be classified simply on the basis of differences in shape. The shapes
commonly recognized are bacillus (rod shaped), coccus (round or spherical
shaped), and spirillum (spiral shaped).
Figure 11.1: Bacterial shapes.
1. Examine prepared bacterial slides under the microscope:
Record characteristics of the cells you observe. Note especially cell shape, size,
colony color and appearance.
What magnification is required to view bacteria?
How can you make sure NOT to break the slides you look at?!!!
2. View different agar plates that have been inoculated with bacteria.
Each colony you observe contains cells that are all descended from one original cell.
Notice the colonies of bacteria growing on the plates.
Compare them as to color, surface, and margin.
3. Using nutrient agar plates, test the presence of air born bacteria.
a. Obtain two agar plates, and a marker.
b. Label one plate “Air”, and add your initials and date on the back of the
plate.
c. Place the plate near a source of moving air, such as an air conditioner or
open window, and leave it for ten minutes.
d. Close the plate and place it upside down in the incubator at 37 C for 2448hr.
e. Divide a second plate on the back into two equal parts and label one side
F.P for finger print and the other side M for milk; add your initials and
date.
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f. On the finger print-labeled side, press your thumb against the agar, and on
the other side add a drop of milk.
g. Close the plate and place it upside down in the incubator.
h. Come to the lab within the next 48 hrs and notice the colonies that grow on
each plate, record your results.
4. Bacteria are also differentiated according to their reaction to a gram stain. This
response is determined by the structure of the cell wall. Gram-positive bacteria stain
purple because they retain the crystal violet dye after being stained by the gram stain
procedure. Gram-negative bacteria appear red because they don’t keep the crystal
violet stain, and they do retain the safranin stain which is red in color.
* Prepare a wet mount slide of specimens from culture as directed by your instructor,
and stain them as follows:
a. Make smears on a microscopic slide of bacteria obtained from Petri dishes
marked gram-positive and gram-negative.
b. Place the slide flat on a desktop and add several drops of crystal violet
solution. Let the stain soak in for one minute.
c. Rinse the stain into the sink by adding distilled water to the edge of the
slide; not immediately on the smear.
d. Apply several drops of iodine solution to the smear and let it set for one
minute.
e. Drain off the iodine solution into the sink and rinse the smear in the sink
with a squirt bottle of 95% ethanol for 15-30 seconds.
f. Flood the smear with several drops of safranin for one-half minute.
g. Rinse the slide again with distilled water and allow it to dry for few
minutes.
h. Examine the slide under the microscope and record which is gram positive
and which is gram negative.
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Exercise 2: Cyanobacteria prepared slides:
Review microscope use (v.important!) & make labeled drawings of
each specimen.
1. Oscillatoria: This cyanobacterium is widespread in aquatic systems. It also
forms a black layer on the surface of flower pots or other surfaces that are
usually wet. Cells are arranged in filaments within a gelatinous sheath. The
filaments oscillate and hence their name.
Figure 11.2: Oscillatoria.
2. Gloeocapsa: Cells are small and spherical and occur in groups of cells
embedded in a colorless gelatinous matrix.
Figure 11.3: Gloeocapsa.
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3. Nostoc: Photosynthetic cells are arranged in a filament embedded in a
gelatinous matrix. Larger cells, which are called heterocysts and are
specialized for nitrogen fixation, occur in the filaments.
Figure 11.4: Nostoc.
4. Anabaena: Anabaena filaments resemble Nostoc but are not embedded in
colonial mucilage. This cyanobacteria is commonly found in plankton of
fresh water lakes. Heterocyst is evident on the filaments.
Figure 11.5: Anabaena.
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Questions:
1. What are the two purposes of nitrogen fixation?
a.
b.
2. What part of the bacterial cell is most involved with Gram staining, and why?
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