Biol 309
Question Bank
Cell Communities
Multiple Choice
1. The orientation of cellulose deposition appears to be determined by.
A. the alignment of microtubules below the cell membrane.
B. the types of phosopholipids in the underlying cell membrane.
C. the density of actin filaments in the cell cortex.
D. movement of vesicles along microtubules.
2. An epithelium consists of:
A. alternating layers of collagen and proteoglycans.
B. fibroblast cells embedded within a thick extracellular matrix.
C. a layer of specialized cells over connective tissue.
D. a group of different cell types encapsulated by connective tissue.
3. Which of the following statements correctly describes gap junctions and plasmadesmata?
A. They both are present in animal cells.
B. These linkages connect the cytoskeletons of adjacent cells.
C. They facilitate the movement of cells over connective tissue.
D. They are large pores linking adjacent cells.
4. The structure of a collagen fiber is most similar to
A. intermediate filaments
C. actin filaments
B. myosin thick filaments
D. microtubules
5. Which one of the following statements best describes ‘proteoglycans’?
A. These are components of the cell cytoskeleton.
B. They creating a swelling force to support tissues.
C. They provide tensile and structural strength to connective tissue.
D. Proteoglycans provide cell-to-cell recognition and binding.
6. Epithelia layer has polarity, which means that:
A. Cells are added to one side and removed from the other.
B. the cells display different properties on either side.
C. there is a different membrane potential on either side.
D. the basal side is oriented toward the basal lamina.
7. Self-renewal of tissues is possible due to the action of:
A. replication of fibroblasts.
C. creation of new extracellular matrix.
B. migration of new cells into the tissue.
D. division of stem cells.
8. Unlike an embryonic stem cell, a somatic stem cell.
A. is incapable of self renewal.
B. will not create terminally differentiated cells.
C. can only give rise to a limited number of cell types.
D. is only present during early stages of development.
Biol 309
Question Bank
Cell Communities
Page 1
9. In the classic experiments by Townes and Holfreter, embryotic ectoderm, mesoderm and
endoderm cells were disassociated and then recombined. The cells subsequently returned to their
original locations within the embryo. Which mechanism most likely allowed the cells to establish
their original organization?
A. As the cells migrated, they bound to other cells with similar cadherin proteins.
B. Embryonic stem cells divided and gave rise to new cells in the original locations.
C. Formation of new tight junctions created the correct polarity of the embryo.
D. The cells moved to their original locations within the embryo extracellular matrix.
10. Which of the above might be functions of tumor suppressor genes? (identify all correct answers)
A. cell junction component
C. cell surface receptor
E. gene suppressor protein
B. gene activator protein
D. DNA repair enzyme
11. Which of the above might be functions of proto-oncogenes? (identify all correct answers)
True/False
1. Each cellulose fiber consists of many cellulose molecules.
2. The orientation of cellulose strand deposition determines the direction in which the cells can
expand.
3. A 3-amino acid repeating sequence high in glycine is characteristic of proteoglycan core proteins.
4. A GAG is a polysaccharide component of proteoglycans.
5. The extracellular matrix of connective tissue is produced by the adjoining epithelial cells.
6.Tight junctions are very important in maintaining the polarity of epithelial cells.
7. When it divides, a stem cell gives rise to another stem cell.
8. Mutations to a tumor suppressor gene often lead to accumulation of other mutations.
9. Typically it takes mutations that activate both copies of a particular proto-oncogene to trigger cell
division.
10. Complete regeneration of entire limbs is possible in humans.
11. Genetic engineering of human stem cells is possible in humans.
12. Typically, a single mutation is all that is required to make a cell cancerous.
Biol 309
Question Bank
Cell Communities
Page 2
Matching
1. Cell junction type
___ Gap junction
___ Tight junction
___ Desmosome
___ Adheren junction
___ Hemidesmosome
Function
A. site of linkage between the ECM and the cytoskeleton
B. site of linkage between the cytoskeleton of adjacent cells
C. a large aqueous channel between adjacent cells
D. couple phosophoslipids to proteopglycans of the ECM
E. form a diffusion barrier within a membrane
F. link intermediate filaments of adjacent cells
2. Molecule
___ Proteoglycan
___ Cadherin
___ Collagen
___ Integrin
Property
A. mediate cell-to-cell recognition and binding.
B. transmembrane proteins that link ECM to cytoskeleton
C. consists of a GAG linked to a core peptide
D. lie inside the cell membrane and bind to tight junctions
E. filamentous protein that is major component of ECM
Fill in, etc
1. As cells migrate, they respond to and modulate connections to the extracellular matrix through the
membrane protein called _____________________. This protein links _________________
filaments of the cytoskeleton through ______________ junctions to _________________ fibers of
the ECM.
2. Cells that allow renewal of specific tissue types are called ________________________; if they
can give rise to a single cell type they called _____________________________, and if they can
give rise to several cell types they are called _________________________. In contrast, cells from
early developmental stages that can give rise to any cell type are called
________________________________.
3. As a cause of cancer, a mutated G-protein might act as an __________________, whereas its
unmutated form would be called a ________________________.
4. Identify in this figure the regions that correspond to the plant cell primary
cell wall, secondary cell wall, middle lamella, and cell membrane.
Biol 309
Question Bank
Cell Communities
Page 3
5. In writing about his investigations of plant cell structure in his classic Micrographia (published in
1695) Robert Hooke was perplexed by the mechanism of transport through plant cell walls:
“But though I could not with my Microscope, nor with my breath, nor any other way I have yet
tried, discover a passage out of one of those cavities into another, yet I cannot thence conclude,
that therefore there are none such, by which the Succus nutritius, or appropriate juices of
Vegetables, may pass through them; for, in several of those Vegetables, whilst green, I have with
my Microscope, plainly enough discovered these Cells or Poles filled with juices… Now,
though I have with great diligence endeavoured to find whether there be any such thing in those
Microscopical pores of Wood or Piths, as the valves in the heart, veins, and other passages of
Animals, that open and give passage to the contained fluid juices one way, and shut themselves,
and impede the passage of such liquors back again, yet have I not hitherto been able to say
anything positive in it; though, me thinks, it seems very probable, that Nature has in these
passages, as well as in those of Animal bodies, very many appropriated Instruments and
contrivances, whereby to bring her designs and end to pass, which 'tis not improbable, but that
some diligent observer, if helped with better Microscopes, may in time detect.”
What have ‘diligent’ observers since that time discovered about transport between plant cells?
6. As a bioengineer of the 24th century, you are called upon to design a new organ for humans living
on Titan, the moon of Saturn, which has an atmosphere of methane. Starting with cells
(‘methacytes’) genetically engineered to extract hydrogen from the methane, the new organ (the
‘methum’) will allow humans to produce ATP from the methane that they breath.
A. Along with methacytes, what are five other cell functions would you also need to include in
the methum?
B. Which cellular function do you believe will be hardest to achieve?
Biol 309
Question Bank
Cell Communities
Page 4
7. The figure to the right shows a simple tissue.
A. Label in the diagram epithelium, fibroblasts, collagen fibers,
intermediate filaments, desmosomes, hemidesmosomes,
connective tissue, and basal lamina.
B. Does the epithelium display a simple or stratified arrangement?
Explain.
8. The diagram to the right shows cells of the skin epidermis.
A. Identify the dermis and epidemis, the regions where one would
find basal lamina, connective tissue, stem cells, partially
differentiated dividing cells, terminally differentiated cells, and
dead cells.
B. Is skin a simple or stratified arrangement? Draw arrows to show
the pattern of cell movement as differentiation occurs.
9. The diagram to the right shows cells of the intestine.
A. Identify a crypt and villus, the regions where one would find stem
cells, partially differentiated dividing cells, and connective tissue,
terminally differentiated cells adsorptive and mucus secreting.
B. Is the intestine epithelium a simple or stratified arrangement?
Draw arrows to show the pattern of cell movement as
differentiation occurs.
Biol 309
Question Bank
Cell Communities
Page 5
For the next two questions, indicate if mutations that either constitutively activate or inactivate
the indicated genes would create a:
mT – mutated Tumor Suppressor Gene OG – Oncogene
N – Neither
Also indicate whether the mutation present on only one chromosome is sufficient, or if mutations
on both homologs would be needed, see the effect of the mutation.
10. In the signal transduction pathway shown in the figure to the right, DNA damage leads to
activation of p53 kinase, which then phosphorylates and
activates the p53 protein, which then activates expression of
the p21 gene. The p21 protein then binds to and inactivates
the G1/S-Cdk (a trigger of cell division), bringing cell
division to a halt.
constitutively
copies to
gene for
activated
see effect
p53 kinase
____
____
p53
____
____
p21
____
____
G1/S-Cdk
____
____
gene for
p53 kinase
p53
p21
G1/S-Cdk
inactivated
____
____
____
____
copies to
see effect
____
____
____
____
11. In this signal transduction pathway, signal transduction
from a membrane receptor leads to activation of a G1/S-Cdk,
which then phosphorylates and inactivates the rb protein.
When active, the rb protein prevents a transcription regulator
from triggering cell division.
copies to
gene for
inactivated
see effect
Mitogen receptor
____
____
G1/S-Cdk
____
____
Rb protein
____
____
Transcription regulator ____
____
constitutively copies to
gene for
activated
see effect
Mitogen receptor
____
____
G1/S-Cdk
____
____
Rb protein
____
____
Transcription regulator ____
____
12. Why does the number of copies of the mutated gene required to see the effect differ for an
oncogene and a mTSG?
Biol 309
Question Bank
Cell Communities
Page 6
13. Cadherin expression is reduced in various types of cancers, and it is suspected that cadherin
expression influences cell metastasis. In one investigation (Lee, et al. 1998. Carcinogenesis 19(6):
1157–1159), the influence of H-cadherin on human breast cancer cells was examined.
A. What are the function of cadherin proteins?
Figure 1. Expression of H-cadherin in several breast cancer cell lines. Northern blots for Hcadherin mRNA were probed with radiolabeled H-cadherin DNA. 15N are normal mammary
epithelial cells; MDAMB435 are a breast cancer cell line; C1 and
C8 are MDAMB435 cells transfected with the plasmid pCDNA3;
S6 and S27 are MDAMB435 cells transfected with pCDNA3
containing the H-cadherin gene.
B. What specifically is being measured in this experiment?
C. Is H-cadherin expression increased or decreased in the
MDAMB435 cancer cells compared to normal cells?
D. Explain the difference in result between C1 & C8 and the
S6 & S27 cell lines. What is the purpose of the C1 & C8
cells in this experiment?
Figure 2. Invasiveness of cell lines. The tendency of the cells to be
metastatic was measured by using 24-well invasion chambers. In
this system, a specific number of cells are applied to the surface of a
porous membrane called Matrigel in culture medium. After 48
hours, the cells that have migrated through the membrane to the
bottom surface were stained and counted. Each cell line was assayed
in triplicate.
E. What do these results suggest about the influence of Hcadherin on the metastatic properties of the cells?
F. Do the results for the various cell lines aggress with the
results presented in Figure 1?
Table 1. Tumorigenicity of the different cell lines. 2x106 cells
were injected subcutaneously into the mammary fat pads of
mice and the size of the tumors was determined after 4 weeks.
G. What do these results suggest about the influence of Hcadherin on the growth rate of tumors?
Cell line
MDAMB435
C1
C8
S6
S27
Avg tumor wt. (g)
170
202 ± 18
238 ± 11
34 ± 5
2±1
H. Explain why H-cadherin may have the observed effects on cell invasiveness and tumor
growth.
Biol 309
Question Bank
Cell Communities
Page 7