Biol 12
Review: Structures of the Cell and Cell Membranes
Sections 1-1, (1-4-phospholipids), 1-5
1
A. Review Questions: With the exception of the blanks, you are not required to answer this set
of questions. However, I highly recommend you go through the questions, and be sure that
you are ABLE to answer them.
1.
2.
3.
4.
5.
List the major chemical components found in animal cell membranes.
Which part of the cell functions as a control centre? Which molecule directs protein synthesis?
What is the difference between chromatin and chromosomes?
What is the role of the nucleoli in the cell?
RIBOSOMES are the dense granules composed of 2 subunits that contain both RNA and protein. They are
the sites of protein synthesis. When several ribosomes are making the same protein, they are arranged in a
functional group called a POLYRIBOSOME
6. What is the structural difference between rough and smooth endoplasmic reticulum? ROUGH IS STUDDED
WITH RIBOSOMES. SMOOTH DOES NOT CONTAIN RIBOSOMES.
7. List 2 functions of smooth endoplasmic reticulum.
LIPID SYNTHESIS
DETOXICFICATION
8. Ribosomes attached to the endoplasmic reticulum produce protein that is destined for the Golgi Apparatus.
9. How does the ER server as a transport system? VESICLES PINCH OFF FROM THE ER AND MOLECULES
ARE TRANSPORTED THROUGH THE CYTOPLASM TO THE GOLGI APPARATUS.
10. Describe the appearance and give the function of the Golgi apparatus. GOLGI LOOKS LIKE A STACK OF
flattened SACS WITH VESICLES THAT PINCH OFF AT THE POSTERIOR END.
11. What is the difference between a vacuole and a vesicle? VACUOLES AND VESICLES ARE BOTH
MEMBRANE BOUND SACS. A VACUOLE IS LARGER.
12. Lysosomes contain hydrolytic enzymes that digest macromolecules. Why is autodigestion important?
GIVES THE CELL THE ABILITY TO DESTROY ITS OWN CELLS WHEN NECESSARY. This is important if
there is a mutation in a certain cell or in the case of development where certain cells need to die in
order for proper form to take place (i.e. hand going through autodigestion to get distinct fingers).
13. List the 2 energy-related organelles of the cell? MITOCHONDRIA-ONLY ONE IN ANIMAL CELLS.
Chloroplasts in plants are a second organelle that is energy related.
14. Describe the structure of the mitochondria. Why is it important to the cell? LARGE, DOUBLE MEMBRANE,
INNER MEMBRANE FORM FINGER-LIKE PROGECTIONS INTO THE ORGANELLE. GENERATES ATP
MOLECULES FOR ENERGY. THIS PROCESS IS CALLED CELLULAR RESPIRATION.
B. Objective Test - completion and short answer questions.
1. Nucleus. The nucleus is enclosed by the (a)
nuclear envelope, which contains (b)
pores
that open into the cytoplasm. At the time of cell division, chromatin (c)
condenses to form chromosomes. The relationship between the nucleoli and
ribosomes is (d)
rRNA synthesis and assembly . DNA within the nucleus
controls (e)
cell function and cell replication .
2. Name the organelles in this drawing of an animal cell.
Biol 12
Review: Structures of the Cell and Cell Membranes
Sections 1-1, (1-4-phospholipids), 1-5
2
a. rough endoplasmic
reticulum
b. vesicles
c. cytoplasm
d. nuclear pores
e. smooth ER
f. nucleolus
g. centriole
h. chromatin
i. cytoskeleton
j. mitochondira
k. nucleus
l. lysosome
m. Golgi Bodies
n. Ribosomes (on the rER)
o. Cell membrane
3. Which
structures in a cell contain DNA?
Nucleus, mitochondria
RNA?
Nucleus (formed there) and ribosomes (they ARE made of rRNA
4. Write the word “mitochondrion” above or below the correct arrow in the equation below. Write the word
“chloroplast” above or below the correct arrow.
mitochondrion
Carbohydrate + Oxygen
Carbon dioxide + Water
chloroplast
5. What are hydrolytic enzymes, and which organelle contains them? POWERFUL ENZYMES USED IN
DIGESTION OF CELL COMPONENTS AND WHOLE CELLS (I.E. BACTERIA). RECYCLING AND DIGESTION.
They are contained in lysosomes.
6. How are the cell membrane and the nuclear membrane similar? How are they
different.
BOTH ARE DOUBLE MEMBRANE ORGANELLES COMPOSED OF PHOSPHOLIPIDS. CELL MEMBRANE IS
EMBEDDED WITH PROTEINS AND LIPIDS TO FORM A MOSAIC LIKE MODEL, WHERE AS THE NUCLEAR
ENVELOPE CONTAINS PORES THAT OPEN INTO THE CYTOPLASM
7. Togetherness. How do these organelles work together?
a. lysosomes and vacuoles. LYSOSOMES CAN COMBINE WITH VACUOLES, RELEASE THEIR POWERFUL
ENZYMES AND BREAK DOWN WHATEVER IS CONTAINED WITHIN A VACUOLE (I..E PROTEIN, LIPIDS
OR LARGER MACROMOLECULES).
b. endoplasmic reticulum + membranes : RIBOSOMES MAKE PROTEINS, ER SENDS THE PROTEINS TO
GOLGI FOR EXPORT
Biol 12
Review: Structures of the Cell and Cell Membranes
Sections 1-1, (1-4-phospholipids), 1-5
3
c. ribosomes and endoplasmic reticulum. MITOCHONDRIA BREAK DOWN GLUCOSE AND RELEASES
ENERGY. CHLOROPLASTS STORE ENGERGY IN GLUCOSE BONDS
e. Golgi Bodies and Endoplasmic Reticulum. ER SENDS LIPOIDS/PROTEINS TO GOLGI FOR PACKAGING.
GOLGI BODIES PACKS PROTEINS FROM ER EXPORT.
c. Matching
E packaging and secretion
C hydrolytic enzymes
A energy production
B protein synthesis
F membrane synthesis
D protein transport
a. mitochondria
b. ribosomes
c. lysosomes
d. rough endoplasmic reticulum
e. Golgi apparatus
f. smooth endoplasmic reticulum
d. Fill in the Blanks
1. SMOOTH ER is an organelle that is thought to have a roll in detoxification of drugs.
2. LYSOSOMES is an organelle in which digestion takes place due to the action of powerful hydrolytic
enzymes.
3. CHROMATIN is a threadlike network in the nucleus that is made up of DNA and proteins.
4. MEMBRANE is a structure that is made up of phospholipids, cholesterol and proteins.
5. LIPID is the component of cell membranes that causes them to have a consistency of light oil.
6. The cristae in mitochondria are used for the production of ENERGY by means of
CELLULAR respiration.
3. The basic structure of the cell membrane is determined by the PHOSPHOLIPIDS but the various functions
of the membrane are carried out by the cell membrane PROTEIN .
4. Give 4 functions of proteins in the membrane.
5. Which type of molecule is easiest to cross a cell membrane, a small non-charged substance soluble in lipid,
or a large, charged molecule?
6. Why is the cell membrane said to be differentially permeable? What is the difference between a passive and
active means in order to assist the passage of molecules across the cell membrane?
7. Is the cell membrane positively or negatively charged on the outside? On the inside?
8. Define diffusion and give an example.
9. Why do lipid-soluble molecules, such as alcohol and gases, diffuse through the cell membrane?
10. Explain why water molecules pass into and out of the cell membrane with relative ease.
11. Define osmosis.
12. What is an isotonic solution? Will water leave the cell?
13. What is a hypotonic solution? Will more water enter or leave the cell? What will happen to an animal cell?
What term is used to describe disrupted red blood cells?
14. What is a hypertonic solution? Will more water enter or leave the cell? What will happen to an animal cell?
What term is used to describe the shrinking of the cytoplasm due to osmosis?
15. Carrier proteins in a cell membrane are required for what 2 types of transport?
16. Describe facilitated diffusion. Does it require energy? Do the molecules move down or up the concentration
gradient?
Biol 12
4
Review: Structures of the Cell and Cell Membranes
Sections 1-1, (1-4-phospholipids), 1-5
17. Define active transport. Does it require energy? Do molecules move down the concentration gradient?
18. The sodium-potassium pump will create a high concentration of NA+
ions outside the cell and
K+
ions inside the cell.
19. What is the difference between endocytosis and exocytosis?
20. Explain the difference between phagocytosis and pinocytosis. Give an example of each.
21. Name the organelle that will form vesicles used for exocytosis. GOLGI APPARATUS Exocytosis is required
for
SECRETION
.
B. Objective Test - Completion and short answer Questions.
1. Diffusion is the movement of molecules from the area of
to the area of
LOW concentration.
HIGH
concentration
2. Osmosis is the movement of WATER across a differentially permeable membrane.
3. A cell is isotonic to a solution of 0.01% sugar. A concentration that is hypertonic is >0.01% SUGAR, whereas a
concentration that is hypotonic is <0.01% SUGAR .
4. If an animal cell is placed in a hypotonic solution, it would LYSE whereas an animal cell placed in hypertonic
solution would
CRENATE
.
5. Cells engaged in the process of actively transporting substances across the membrane expend
energy .
6. Label this diagram of the cell membrane:
a. carbohydrate
chain
b. glycoprotein
c. glycolipid
d. cholesterol
e. cytoskeleton
f. membrane
protein
8. Give an example of :
a. diffusion in the body: O2 INTO BLOOD IN LUNGS, NEUROTRANSMITTERS ACROSS SYNAPSE
b. facilitated diffusion:
SODIUM OR POTASSIUM CHANNELS IN NERVE CELLS
c. active transport: NUTRIENTS INTO INTESTINAL CELLS, SALT OUT OF KIDNEYS, SODIUM/POTASSIUM
PUMP IN NERVE CELL.
Biol 12
Review: Structures of the Cell and Cell Membranes
Sections 1-1, (1-4-phospholipids), 1-5
5
9. List three ways in which active transport differs from the process of diffusion across a cell membrane.
a. GOES FROM LOW [ ] TO HIGH [ ] ( AGAINST [ ] GRADIENT)
b. REQUIRES ENERGY
c. REQUIRES TRANSPORTER PROTEIN
10. List two ways in which facilitated diffusion differs from active transport.
a. DOESN’T REQUIRE ENERGY
b. FOLLOWS THE CONCENTRATION GRADIENT
11. By which method would you predict that these molecules would enter a cell?
a. oxygen DIFFUSION
b. glucose FACILITATED/ACTIVE/DIFFUSION
c. potassium (K+) FACILITATED/ACTIVE d. water OSMOSIS
12. A. a; B. b; C. b
13. Consider this diagram. The membrane is differentially permeable to glucose and water but not to protein.
a. Will the concentration of water stay the same on side A or become greater or less
with time?
Greater
b. Will the concentration of protein on side A stay the same or become greater or less
with time?
It will decrease since H20 will move in
c. Glucose will cross the membrane in which direction?
From A to B
d. On which side will the hydrostatic pressure increase? Side A
e. What will happen to the level of the solution on each side?
increase, Side b will decrease
Side A will
14. Red blood cells neither gain nor lose water when put into 0.9% NaCl.
a. What term is used to designate the tonicity of 0.9% NaCl for red blood cell? isotonic
b. Are the solutions below hypertonic or hypotonic to red blood cells?
15% NaCl hypertonic
0.001% NaCl
hypotonic
Review: Structures of the Cell and Cell Membranes
Sections 1-1, (1-4-phospholipids), 1-5
Biol 12
6
c. Beside the words below write either 0.9% NaCl, 15% NaCl, or 0.001% NaCl.
Hemolysis 0.001% NaCl crenation 15% NaCl
neither of these 0.9%NaCl
15. Sea urchin egg are isotonic to seawater. Consider these conditions:
(1) Eggs are in seawater.
(2) Eggs are in 65% seawater (35% distilled water)
(3) Eggs are in pure distilled.
True (T) or False (F)
t
a. Under condition 1, the system is already in equilibrium.
t
b. Under condition 2, the eggs will swell.
F
c. Under condition 3, the eggs will shrink.
16. Transport
a. A scientist notes that of three monosaccharides - glucose, mannose, and galactose - glucose enters cells
much faster than the other two. What process is at work?
FACILITATED TRANSPORT
/ACTIVE TRANSPORT
b. A scientist determines that the concentration of phosphates outside a cell is 5 mg/L and inside the cell it is 75
mg/L. By the law of diffusion, which way would you predict phosphate to go - in or out of the cell? OUT The
scientist notes that the cell continues to accumulate phosphates. What mechanism is at work? ACTIVE
TRANSPORT
Completion Question.
18. SOLVENT
is a fluid such as water that dissolves solutes.
19. CRENATION/PLASMALYSIS is the contraction of cell contents due to the loss of water.
20. DIFFUSION is the movement of molecules from an area of greater concentration to an area of lesser
concentration.
21. CHOLESTEROL
is a lipid molecule that lends stability to the phospholipid bilayer.
True or False.
If you believe the statement to be false, then rewrite the statement as a true one.
22. If a red blood cell is placed in distilled water, it will shrink.
Answer: F
Restatement: If a red blood cell is placed in distilled water, it will SWELL
23. If a red blood cell is placed in a high salt solution, salt will enter the cells, giving them a strange appearance.
Answer: F
Restatement: if a red blood cell is placed in a high salt solution, the cell will CRENATE AND
SALT PROBABLY WON’T MOVE
24. If a cell uses active transport to take in salts, then osmosis will follow.
Answer: T
Restatement: ASSUMING THAT THE TRANSPORT IN CREASES THE [SOLUTE] INSIDE
THE CELL.