BI 171 - Fourth Exam - 2002
Answer Key
Multiple Choice.
Place the letter of the choice that
best answers the question on the line to the left.
Two Points Each. NOTE: "e" answers are never the correct
answer.
___B___ 1. A common reporter gene codes
for
a. Medical
proteins
b. Antibiotic resistance
c. Industrial
proteins
d. Culture shape
e. Bad spelling and grammar
...when genes are inserted into cells, reporter genes are included so the
successful cells can be detected. With antibiotic resistance, a dose
of antibiotic removes all of the bacterial cells that didn't pick up the
inserted genes.
___D___ 2. Intermediate filaments are
most commonly found in cells that
a. That
crawl
b. Are preparing for cytokinesis
c. That
swim
d. Are under mechanical stress
e. That can’t make up their minds
...it's one of the few circumstances clearly associated with
intermediate filaments.
___C___ 3. An acrosome features
importantly in
a. Spindle
function
b. Morphogenesis
c. Fertilization
d. Cytokinesis
e. The "too much information" concept
...it's the chamber in a sperm that contains the enzymes used to get into
the egg cell.
___B___ 4. Which best describes histones?
a. Microtubule Organizing
Centers
b. Spools for winding up DNA
c. Synapsis
organizers
d. Electrophoresis gels
e. Deeper than hertones
...match the term to the description.
___C___5. The chance of an AB parent
and an O parent having an A child is
a. 0% b.
25% c.
50% d.
75%
e. Don’t I need a calculator (or a mathematician) for this?
...since the O parent has 2 O alleles, each child will either get an A and
an O (Type A blood) or a B and an O (Type B blood), a 50-50 chance.
___C___6. Which is the proper transduction pathway?
a. Protein kinase, 2nd messenger, G protein, enzyme
b. Enzyme, 2nd Messenger, G protein, protein kinase
c. G protein, 2nd Messenger, protein kinase, enzyme
d. Enzyme, 2nd messenger, protein kinase, G protein
e. How can I pick an order if none of the steps look familiar?
...the receptor sets off the G protein (the 1st messenger, even if it isn't
called
that), then the 2nd to get the message into the cell, to set off the protein
kinase which actually activates the enzyme that will produce the cell
response.
___B___7. Muscles depend on the activity of
a.
Cilia
b.
Microfilaments
c. Microtubules
d. Coated
pits
e. Something in spinach
...specifically, actin and myosin microfilaments.
___A___8. In prokaryotes, active
ribosomes would be found
a. In contact with
chromosomes
b. On endoplasmic reticulum
c. On the inner cell membrane surface d.
Any of these places
e. Drunk and disorderly on any Saturday night
...the steps in protein synthesis happen right next to the DNA codes, since
there's
no nuclear barrier to keep them separate.
___C___9. Which pair are most closely related?
a. rRNA -
DNA
b. Spindle - telomere
c. Kinetochore - centromere
d. Basal body - coated vesicle
e. Biology class - insanity
...a kinetochore is part of a centromere - even ribosomal RNA and DNA
aren't that close.
___A___10. In eukaryotes, genes
for pathway proteins are commonly
a. Distributed
randomly
b. Linked
c. On the sex
chromosomes
d. Placed in sequence
e. Blacktopped over
...unlike prokaryotes, which have them in sequence so proteins "roll
off"
ribosomes by the codes and go to work, eukaryotes make the proteins
elsewhere, so there's no need to string the
codes together.
___A___11. Promoters and enhancers
are generally attached to
a.
DNA
b. Cell
membranes
c. Receptors
d. Nuclear envelopes
e. Advertising agencies
...they promote and enhance DNA transcription.
___D___12. In prokaryotes, a protein
needed continuously or regularly is called a
a. Inducible
protein
b. Regulon
c. Pathway protein
d. Housekeeping
protein
e. Minimum-wage slave
...it seemed like a continuous process to whoever named it...
___B___13. Under ideal conditions, mitochondrial
DNA
a. Is
diploid b. Inherits along
maternal lines c. Does not
mutate
d. Is only
single-stranded
e. Feels superior to all the other NAs
...an individual's mitochondria originated in the egg cell, a maternal cell.
___A___14. Red-green color blindness is a sex-linked
trait. When a boy is color blind, he
inherited the allele(s) from
a. His
mother
b. His
father
c. Either parent
d. Both
parents
e. Great Grandad, the crazy one
...it's carried on the X chromosome, passed from Mom (Dad sent a Y to
make a boy).
___D___15. The eventual fates of embryonic cells are determined very early in
a.
Mitosis
b. Radial
cleavage
c. Meiosis
d. Spiral cleavage
e. Any Steven Seagal movie
...it is one of the characteristics that goes with that style of cleavage.
___B___16. A karyotype is
a. Determined by Southern Blotting
b. Particular to a species
c. Particular to an individual
d. A product of two different genes
e. Some sort of old-fashioned printer
...a combination of chromosome number and all of the types.
___A___17. Steroid hormones, unlike other messenger molecules, can
a. Attach directly to chromosomes
b. Set off multiple receptors
c. Access multiple transduction pathways
d. Be deactivated with carbohydrates
e. Make you act like an idiot
...being lipids / lipid-soluble, they can move through the membranes to
directly access a cell's DNA
___C___18. To do Southern blotting, it is necessary to have
a. Plasmids do part of the work
b. An equal mix of male cells and female cells
c. Cells that make a lot of the target protein
d. All of these
e. Many bottles of Kentucky-made fermented beverage
...it requires tagged mRNA, for which cells with lots of a particular
protein will have.
Short Answer.
Pick NINE questions to answer in the spaces
provided.
NOTE: if you answer MORE than nine, only the first
nine will be corrected.
Four Points each. Partial credit is possible.
| 1. What are two different applications for gene transfer in crop plants? | |
|
Herbicide Resistance |
Added Nutrients |
| 2. What are two different uses for microtubules in cells? | |
|
Cores of Cilia /
Flagella |
Spindle |
| 3. Chromosome numbers (low or high) in organisms are a balance between what two advantageous features? | |
|
Variation in Offspring (with High Numbers) |
Control of DNA Distribution when Cells Divide |
| 4. What are two entirely different types of functions done by, for example, an epithelial cell during interphase? | |
|
Regular Cell Role Functions |
Preparation for Cell Division |
|
5. Briefly explain (don’t just
define!) How position effect works. ...a gene in a tightly-wound area of a chromosome is harder to "get at" for expression (in other words, a gene's placement on a chromosome (position) has an effect on its use.
|
|
|
6. Briefly explain the purpose of Okazaki
fragments. ...they allow replication of DNA of the strand going in the "wrong" direction.
|
|
|
7. Briefly explain why a base insertion
is a much more powerful mutation than a substitution. ...sticking an extra base in changes that codon and every codon from there on, since it changes the "reading frame" of the gene - a substitution of one base for another just changes the codon that base is in.
|
|
| 8. Give two general advantages that can be gotten from metamorphosis between life-cycle stages. | |
| One stage can avoid directly competing with another | One stage can be used to spread the population out |
| 9. Briefly describe the two ways that polyspermy is avoided. | |
| Fast - Egg cells chemically shut out sperm after the first one enters by depolarizing the membrane and breaking down enzyme receptors | Slow - a membrane seals off the fertilized egg, or polyspermous cells spontaneously die |
|
10. What is an exon? ...part of a gene sequence that will be clipped out and will be used to produce the coded protein. Introns are the clipped-out parts and are discarded.
|
|
| 11. What are two life-style types that benefit from alternation of generations? | |
|
Immobile - sexual form is mobile. Stage fits changeable environment. |
Sexual stage limited in size by need to be close to wet surface. |
|
12. Give an example of a trait that
is passed on epigenetically. ...anything passed along in some way other than through genes - cell parts, learned behavior, foraging territory, etc.
|
|
| 13. Transfer RNA (tRNA) binds to what two other molecules? | |
| Messenger RNA |
Amino Acid |
|
14. What does the signal region of a protein do? ...it attaches to transport proteins within a cell. |
|
| 15. What are two molecular-level ways that inducers can induce? | |
| They can start activator proteins | They can shut off repressor proteins |
Long Answer.
Select and answer completely any four
of the following questions.
Note: if you answer more than four, only the
first four will be corrected.
Seven Points Each. Partial credit is possible.
| 1. Give, in order of occurrence, the phases of mitosis, and for each, tell one distinct thing that happens particularly during that phase. INTERPHASE is NOT part of mitosis. | |
| PROPHASE | Many choices - chromatin and chromosomes become visible to a light microscope; spindles form; nuclear envelope disappears; spindles attach to and move chromosomes... |
| METAPHASE | Chromosomes occupy the cell equator; the chromatids separate into individual chromosomes and start to separate. |
| ANAPHASE | Chromosomes are pulled to the poles; cell plates start to form in plant cells. |
| TELOPHASE | Many choices - nuclear envelope reforms; spindles detach from chromosomes and break down; chromosomes unwind to chromatin and disappear to light-microscope view... |
| 2. Explain, step-by-step (don’t be constrained by the number of lines) the Polymerase Chain Reaction (PCR) process. |
| Heat DNA sample until strands separate. Lower temperature and allow primers to attach. |
| Use heat-resistant DNA polymerase to replicate primed strands. |
| Heat and separate, cool and copy, over and over. |
| Enough duplicates of part of original sample exist for analysis. |
|
3. Here it is - determine the sequences of the named
molecules from this DNA sequence. DNA_______________________________________________________________________ mRNA A U G - U C G - G G G - U G U - A A C - G U A - C U A -U A A
|
|
| 4. Name the three embryonic germ layers, and for each give one organ, structure, or system that forms from that layer. | |
| ECTODERM | Skin & Surface Structures; Nervous System Structures. |
| ENDODERM | Digestive System & Associated Structures. |
| MESODERM | Muscles & Internal Skeleton; Internal Organs not in Systems above. |
| 5. In any organism with genders, give three sets of differences there would be between: | |
|
SPERM |
EGG CELLS |
| Are much bigger, since this is where the food for the next generation is stored. | Are much smaller, since they have to be more mobile. |
| Just need to be somewhere that sperm can reach them. | Need to be able to get to where the egg cells are. This is done in various ways. |
| Are produced in much lower numbers, since each is a bigger investment of resources. | Are produced in much larger numbers, since their chance of reaching an egg cell is low. |
| During meiotic production, one cell retains all of the food and becomes an actual egg cell, while polar bodies are used to discard unneeded chromosomes. | Each meiosis produces four functional sperm cells. |
| 6. Whatever you choose from the history of discoveries about genetics, make sure that your list of three discoveries is in chronological order | |
|
Researcher or Research Organism |
Discovery |
| Mendel / Pea Plants | Basic Rules of Inheritance; Dominance |
| Mice (Britain & Netherlands) | Linkage, Crossing Over |
| Fruit Flies | Mutations |
| Neurospora | Mutations affect single enzymes |
| Phages / Viruses | DNA can carry complex information by itself |
| Watson and Crick | Double-Helix Structure of DNA; DNA replication |
| Human Genome Project | Analysis of large quantities of DNA |
| 7. Give three separate sets of differences between mitosis and meiosis. | |
| MITOSIS | MEIOSIS |
| Single set of steps | Two sets of steps |
| Can produce 2 cells | Generally produces 4 cells |
| Prophase puts chromosomes randomly in cell equator | Prophase I pairs homologous chromosomes in cell equator |
| Crossing over should not occur | Crossing over often occurs |
| Anaphase separates chromosome strands | Anaphase I separates homologues, which stay double-stranded |
| Involved in asexual reproduction of cells | Involved in production of gametes for sexual reproduction |
NO KEY for BONUS QUESTIONS.
Answer as many or as few as you wish. You can't lose points on the rest of the exam by getting these wrong. Partial credit is possible.
How are eukaryotic and prokaryotic flagella different? Two Points each.
What is the evolutionary implication of actin being a very similar molecule no matter where it’s found? Three Points.
What’s the relationship between vestigial structures and junk DNA? Three Points.
What lucrative research fields are vigorously investigating telomeres? Two Points each. What is each investigation trying to find out? Three Points each.
Potentially, what bad thing could result from being given unnecessary antibiotics (Two Points), and briefly how could that come about? (Three Points)
What is indicated by "puffs" in insect chromosomes? Three Points.
What sorts of organisms were being studied by the inventor of the Polymerase Chain Reaction? Three Points.
What assumption about stem cell use will probably turn out to not be true? Three Points.
What non-spherical shape are blastulas commonly
(Two Points), and why? (Three Points)
GENE TRANSLATION TABLE
CODONS ON MESSENGER RNA|
First Letter |
SECOND |
LETTER |
Third Letter |
||
|
U |
C |
A |
G |
||
|
phelyalanine |
serine |
tyrosine |
cysteine |
U |
|
|
U |
phelyalanine |
serine |
tyrosine |
cysteine |
C |
|
leucine |
serine |
STOP |
STOP |
A |
|
|
leucine |
serine |
STOP |
tryptophan |
G |
|
|
leucine |
proline |
histidine |
arginine |
U |
|
|
C |
leucine |
proline |
histidine |
arginine |
C |
|
leucine |
proline |
glutamine |
arginine |
A |
|
|
leucine |
proline |
glutamine |
arginine |
G |
|
|
isoleucine |
threonine |
asparagine |
serine |
U |
|
|
A |
isoleucine |
threonine |
asparagine |
serine |
C |
|
isoleucine |
threonine |
lysine |
arginine |
A |
|
|
*START* methionine |
threonine |
lysine |
arginine |
G |
|
|
valine |
alanine |
aspartate |
glycine |
U |
|
|
G |
valine |
alanine |
aspartate |
glycine |
C |
|
valine |
alanine |
glutamate |
glycine |
A |
|
|
valine |
alanine |
glutamate |
glycine |
G |