Unit 2: Cells
& Microscope
Cell Objectives:
1. Know the Organization of life.
2. Know who first saw cells.
3. Know The Cell Theory.
4. Know the differences between Prokaryotic and Eukaryotic cells.
5. Know the 12 organelles in Eukaryotic cells.
6. Know the differences between plant and animal cells.
Cells
All living things are composed of cells.
A cell is a membrane-covered structure that contains all of the materials necessary for life.
An organism is anything that can live on its own.
Organisms can be unicellular or multicellular.
Unicellular: Made up of only one cell. They usually need to be seen using a microscope.
Multi-cellular: Made up of more than one cell. They have groups of cells that work together.
Discovery of Cells
Cells were discovered in 1665 by Robert Hooke.
He was looking at cork from the bark of a tree using a microscope.
Anton van Leeuwenhoek saw the first living cells in 1673.
He observed pond scum, blood and was the first person to see bacteria.
The Cell Theory
Scientists later discovered a lot more about cells using more powerful microscopes.
They developed The Cell Theory.
The Cell Theory States:
o Cells are the smallest living thing
o Every living thing is made of cells
o Cells divide to form new cells
Theodor Schwann developed the theory in 1839.
Organization of Life
For Multi-cellular organisms:
cells
Make up
tissues
Make up
organs
Make up
organ systems
Make up
organisms
Types of Cells
Prokaryotic:
Cells that do NOT have a nucleus
Do NOT have membrane bound
Circular DNA
Bacteria
Eukaryotic:
Cells that DO have a nucleus
Do have membrane bound
Linear DNA
All other organisms
organelles
organelles
Cell Parts (Organelles)
Eukaryotic Cells:
• cytoplasm
• endoplasmic reticulum
• cell membrane
• mitochondria
• cell wall
• chloroplast
• nucleus
• Golgi complex
• nucleolus
• vacuole
• ribosomes
• lysosomes
Types of Eukaryotic Cells
Animal:
Plant:
Types of Eukaryotic Cells
Animal:
Plant:
Function of cell parts
1. Cytoplasm
 Jelly-like fluid inside cell
 Organelles are found floating here
Function of cell parts
2. Cell Membrane
 Protects the cell
 Keeps cytoplasm inside
 Allows materials in and out of the cell
Function of cell parts
3. Cell Wall
 Provides strength and support to
 Found only in plant cells
 Gives plant cells their square shape
Cell wall
Cell membrane
cell membrane
Function of cell parts
4. Nucleus
 Control center of the cell = “brain”
 Where DNA is found
5. Nucleolus
 Stores materials to
 Found inside nucleus
make ribosomes
Function of cell parts
6. Ribosomes
 Site of protein synthesis
 Amino acids are joined together to make proteins.
 Are found in cytoplasm or attached to
 Smallest but most abundant organelle
endoplasmic reticulum
Function of cell parts
7. Endoplasmic Reticulum (ER)
 Internal delivery system
 Makes lipids and other materials for inside and outside the cell.
 Breaks down drugs and other harmful chemicals.
 May be covered with ribosomes (Rough Endoplasmic Reticulum)
 Found near nucleus
Function of cell parts
8. Mitochondria
 Powerhouse of the cell
 Energy for the cell is made here from
 Surrounded by two membranes
nutrients
Function of cell parts
9. Chloroplast
 Absorbs sunlight to help plants make nutrients for energy
 Contains chlorophyll (green pigment)
 Found only in plant cells
Function of cell parts
10. Golgi Complex
 Materials are packaged in vesicles
 Located near the cell membrane
for shipment outside of the cell.
Function of cell parts
11. Vacuole
 Stores water and other liquids
 Large vacuoles found in plants
Contractile Vacuole:
 Squeezes excess water
out of the cell
Function of cell parts
12. Lysosomes
 Digest (breakdown) materials found in
 Get rid of wastes
 Protect the cell against invaders
 Found in Animal cells
vesicles with enzymes (chemicals).
cell wall
cell membrane
lysosome
Animal Cell
chloroplast
Plant Cell
cytoplasm
nucleolus
nucleus
DNA
ER
mitochondria
Golgi Complex
ribosome
vacuole
Comparing Plant & Animal Cells
Animal
vacuole
nucleus
lysosomes
Plant
Both
mitochondria
cytoplasm
ribosomes
Golgi complex
nucleolus
Cell membrane
ER
DNA
Cell wall
Chloroplast
Microscope Objectives:
1. Know the parts of the microscope.
2. Know the functions of microscope parts.
3. Know how to determine orientation of an object under the microscope.
4. Know how to determine magnification, field of view
5. Know proper technique to use microscope.
and size of an object.
Microscope parts
Use this diagram to label your microscope picture
Microscope Functions
Eyepiece:
Arm:
The part you look through. Where you place your eye.
Attaches eyepiece to the base.
Body tube:
Supports the eyepiece
Coarse adjustment knob:
This moves the stage up and down to get object into
initial focus.
NEVER use under high power.
Fine adjustment knob:
Used to make small adjustments to the focus.
Microscope Functions
Nosepiece:
Rotating piece that changes objectives (low & high)
Objectives:
Lens that magnify the object
Stage:
The place where the specimen is placed.
Stage clips:
Holds the specimen slide in place.
Diaphragm:
Allows different amounts of light through the slide.
Light source:
Reflects light onto the stage to observe specimen
Base:
Supports the entire microscope
Determining total magnification
Multiply the magnification of the eyepiece by
the magnification of the objective.
Eyepiece = 10x
Objective = 4x
Total magnification = 10 x 4 = 40x
Eyepiece = 10x
Objective = 40x
Total magnification = 10 x 40 = 400x
Object Orientation
cover slip
e
slide
As you look through the eyepiece the image you
see is upside down and backwards from the
specimen on the slide.
If you move the slide to the left the object
moves to the right in the eyepiece.
If you move the slide to the right the object
moves to the left in the eyepiece.
Field of View
Each mark = 1 mm or 1000 μm
100x
Determine the field of view by
counting marks under low power.
Field of view = 3mm or 3000 μm
Determining object size
Using the determined field of view:
1. Count the number of cells in a row.
100x
1. 6 cells
2. Divide the number of cells into the
field of view in μm.
2. 3000 μm / 6 cells = 500 μm (size of one cell)