Download Exam 3 Full v2 Bio200 Sum14

Biology 200, Summer 2014
Exam 3
Name: ________________________________________
Section: (circle one) A or B
TA: _______________
Biology 200
Summer Quarter 2014
Exam #3
DO NOT OPEN EXAM UNTIL DIRECTED TO DO SO
 Make sure you have 6 pages, including this one. Print your name and
information on ALL pages.
 Please use a pen. Pen is much easier to read, even with extensive
crossing-out. Pencil-written exams are acceptable, but may not receive full
credit to penciled answers on regrades.
 When asked, provide concise and clearly written answers. We may
deduct points if you do not fully answer the question or if your answer is too
vague or too confusing for us to follow. Extra information, if incorrect, will
lose points.
 Limit your answers to the space provided. If you need extra space, you can
use the bottom of this first page. Indicate “on first page” where necessary.
Page
Points Awarded
2
out of 18 points
3
out of 22 points
4
out of 23 points
5
out of 19 points
6: Take
home
out of 18 points
Total:
out of 100 points
1
5
4
2
3
1
5
Exam 2
Name:_____________________________
[18 points] Gametogenesis and genetic cascades
The following questions refer to gametogenesis and genetic cascades. Unless directed otherwise, you can assume that the
gene products controlling meiosis in mammals operate similarly to the genetic cascade seen in fruit flies.
/3 1a) Refer to the diagrams I and II below. Where will the gametes in each diagram go once they
complete meiosis? How will they get there from where they are now? Explain in 1-2 sentences, max.
I.
II.
/4 1b) A single gene product is responsible for turning on all spermatogenesis. However, removing
all copies of this gene (and the RNAs and proteins it produces) will not stop spermatogenesis once it
is started. Explain this result in 1-2 sentences, max.
/4 1c) What molecule is most likely found in follicular cells?
Mark the single best answer. Then, explain why you chose that answer in 1 sentence or less.
_____ A receptor for sperm signals
_____ A gap junction for connecting to an oocyte cell
_____ A large number of lysosome organelles
/4 1d) The darker areas of the morula shown indicate higher concentrations of a transcription
factor. How can this single factor dictate that the left cells become body and the right cells become
extraembryonic? Answer in 1-2 sentences, max.
/3 1e) Analyze the diagram on the first page. Fill in the numbers corresponding to the correct descriptions.
_____ An example of replicated chromosomes in a 2N cell
_____ An example of unreplicated chromosomes in a 2N cell
_____ An example of unreplicated chromosomes in a 1N cell
Total: _____
Page 2 of 6
Exam 2
[15 points] Fertilization
The chart shown depicts the fertilization rates of
several different mutants. Using this data,
answer the questions below.
/5 2a) What is the rate of fertilization for
the JCF protein mutation? Explain your
numerical answer in 1-2 sentences, max.
Name:_____________________________
Gene
Molecular details
Fertilization rate of
the knockout mutant
Resact
Bindin
Resact
receptor
JCF protein
10-amino acid protein
21.3%
4.4%
21.3%
Fertilizin
JCF
receptor
Mystery
mutant
Intermembrane protein
A component of the jelly
coat
Intermembrane protein
Fertilization same; fitness
decreased.
4.4%
8.5%
100%
/5 2b) Imagine that several species of plankton prey on sea urchin sperm.
Mark all reasonable statements about this system:
_____ Releasing resact is a useful hunting strategy for these plankton.
_____ Plankton bind/digest the resact receptor but almost never bind/digest molecules of bindin.
_____ Plankton find the sperm by binding to jelly coat proteins.
_____ Because plankton find ATP and actin monomers nutritious, sperm are a good food source.
_____ Releasing digestive enzymes through the acrosomal reaction would be a good defense strategy
for sperm.
/5 2c) The mystery mutation is in a gene that is important for a fertilization-related process that we
discussed in class. It does not decrease the ability of the sperm and egg to find each other and join
their membrane, but this mutation does decrease overall fitness. Explain this mechanism in 1-2
sentences, max.
Proliferation
/7 3) Diagram the process of cleavage from a single cell to the 8-cell stage in a species that uses
spiral cleavage. Indicate any special features of this cleavage type that are not found in the other
three.
Total: _____
Page 3 of 6
Exam 2
Name:_____________________________
[23 points] Godzillan development
Besides the the size and the tremendous amount of radiation involved, Godzilla’s post-gastrulational
development is strikingly similar to that seen in chickens.
/4 4a) Godzilla cells are very large and require extreme amounts of nutrition. Do you think
Godzilla embryos go through body folding relatively earlier or later than chicken embryos?
Answer in 1 sentence or less.
/3 4b) Choose the single best statement:
_____ Godzillan neurulation is completed before gastrulation.
_____ Anterior Godzilla cells at the anterior move towards the posterior during body folding.
_____ Extraembryonic Godzillan cells have no contact with the yolk.
/4 4c) The Godzillan notochord seems to differentiate into the precursors of spiny appendages
along the spinal column. Is this similar or different compared to the notochord in chickens?
Answer in 1-2 sentences, max.
/4 4d) Because Godzillan cells are so large, each cell moves more slowly when migrating to a new
location in the embryo. What movements are there in neurulation that will take longer for Godzillan
embryos? Answer in 1-2 sentences, max.
/4 4e) You transplant a cell from a Godzilla somite into a chicken somite. The cell would normally
be part of Godzilla’s claws, but it instead forms part of a perfectly normal chicken wing. What are
two hypotheses that you could draw from this experiment? Answer in 1-2 sentences, max.
/4 4f) Given the large similarity between developmental schemes, mark all reasonable expectations:
_____ Somite cells will develop into mesodermal cell fates.
_____ Godzillan gastrulation and neurulation can be occurring simultaneously in the embryo.
_____ Somites in Godzilla are likely to form first in the anterior region of the embryo.
_____ Signals that determine Godzillan cell fate are likely to come from a combination of endodermal
cells, notochord cells, mesodermal cells, and other somite cells.
Total: _____
Page 4 of 6
Exam 2
Total: _____
Name:_____________________________
Page 5 of 6
Exam 2
[19 points] Inducer infection outbreak
Name:_____________________________
A new disease is emerging in birds. This disease is leading to increased developmental defects in a specific
group of chickens. We know that: a) this disease correlates with infection by an abiotic parasite, b) the infection
is localized to the inducer group of cells (known as Henson’s node in chickens) and c) infections are most
common in a small group of poultry farms that have unusually bad sanitation practices. Infections are only
dangerous if they occur before the blastula stage.
/4 5a) Most of these infected chicken embryos have normal gastrulation but only in a very small
region of the embryo. Explain why this is happening, in 1-2 sentences.
/4 5b) This infection inserts molecules into the host cell nucleus. How can this cause mutations that
lead to this disease? Diagram a simple mutation mechanism.
/4 5c) Would you expect infections of the Henson’s node cells to spread to cells in all three tissue
types (ectoderm, mesoderm & endoderm) or to stay in the ectoderm? Answer in 1-2 sentences.
/3 5d) A nearby farm reports an emerging related disease. New developmental defects still occur,
but they seem to be transmitted only genetically within families of chickens. The disease is no longer
infectious. What has happened to the virus? Answer in 1-2 sentences.
/4 5e) This infection proved extremely difficult to cure. Why was it so difficult compared to other
developmental defects or bacterial infections? Mark all correct answers.
_____ Virus evolution is extremely rapid which produces more variability in genetic information.
_____ Virions can infect each other, so viruses have an ample supply of ribosomes to use.
_____ Most viral mutations are likely to make the virus more infectious.
_____ Virions can incorporate host membrane proteins which helps to avoid immune detection.
Total: _____
Page 6 of 6
Exam 2
Name:_____________________________
[17 points] This take home portion should be completed before the exam and turned in at the start of the exam. You can
work with other students, but your words must be obviously your own. Neatness and clarity are important. Course staff
(TAs, Ben, or Kyle) will politely refuse to answer questions that directly relate to this take-home portion. You can remove
the instructions on this sheet if you want more room on your version to turn in. Creativity will help.
/18 6) The diagram below shows a very simple organism. There are only 12 cells in the adult stage. Build a
series of stages that show the development of this creature from a zygote. An educated observer should be able
to tell from your diagram alone how each cell lineage and adult cell developed. Your diagram does not need to
be three dimensional, but it should explain the development. Additionally, this diagram should include a
clearly labeled and diagrammed example of each of the following:
1) cell differentiation
2) cell-to-cell signaling
3) cell proliferation
4) developmentally-patterned cell migration
5) developmentally-patterned apoptosis
6) hierarchical transcription factor control
7) cytoplasmic or maternal determinant
Adult stage (side view, each shape is a single cell):
Adult stage (top view):
Adult stage (front view):
Diagrams will be graded on the following rubric:
14 pts (2 pts each): Clear and correct examples of all elements in the example list
4 pts: Cohesiveness of the overall diagram as an explanation for development of this organism
Total: _____
Page 7 of 6
Exam 2
Name:_____________________________
NOTE: You can use any format that you find useful to answer this question. Larger or multiplesheet answers are fine, but be sure to put your name, lecture section and TA on each page.
Total: _____
Page 8 of 6