Download Quiz 6-KEY

Quiz 6-KEY
Name_____________________
Atoms to Ecosystems – W09
Group Name_______________
Part 1- Circle the single best answer for the following questions.
1. We now know that two of the genes Mendel studied, that for flower color and that for
seed color, are both located on chromosome 1. Yet Mendel’s results suggested that these
two genes were inherited independently of one another. This is because
a. Mendel misinterpreted his results.
b. the genes are located very close to one another, allowing for crossover.
c. the genes are located far from one another, allowing for crossover.
d. the genes are located very close to one another, preventing crossover
e. the genes are located far from one another, preventing crossover
2. The most common phenotype in a population is called the
a. dominant allele
b. recessive allele
c. wild-type
d. mutant
e. independent
3. A recessive allele on the X chromosome is responsible for red-green color blindness in
humans. If a colorblind woman has children with a man with normal vision, what is the
probability that this couple’s son will be color-blind?
a. 0
b. ¼
c. ½
d. ¾
e. 1 (all)
f. impossible to predict
4. A woman and her partner both show the normal phenotype for pigmentation, but both
had one parent who was an albino. Albinism in humans is an autosomal recessive trait.
Based on this information, what is the probability that their first child will be an albino?
a. 0
b. ¼
c. ½
d. ¾
e. 1
5. In snapdragons, heterozygotes have pink flowers while the two homozygotes have either
red or white flowers. When plants with red flowers are crossed with plants with white flowers,
what proportion of the offspring will have pink flowers?
a. 0%
b. 25%
c. 50%
d. 75%
e. 100%
6. The example in question 5, at the organismal level, is best described as
a. incomplete dominance
b. complete dominance
c. codominance
d. epistasis
e. crossover
7. You’re studying the inheritance of two genes known to be located on the same
chromosome, 25 map units (centrimorgans) apart, thus you expect
a. the traits to be sex-linked, and affect only males
b. 25% recombination frequency
c. 75% recombination frequency
d. a 3:1 ratio of phenotypes in your F2 generation
e. a 9:3:3:1 ratio of phenotypes in your F2 generation
Part 2- Short Answer.
8. In cats, there is a gene known as Agouti (H) which produces fur with different colored
bands on each hair. The recessive allele (h) for this gene produces hair which is a solid color
from end to end. In addition, there is a second coat color gene which has a recessive albino
allele (a). Individuals that are homozygous recessive at this locus cannot produce any coat
color pigment, resulting in an albino cat with white fur and pink eyes.
a. An albino female cat is mated to a solid brown male cat. All of their offspring are
Agouti. What are the genotypes (at both these loci) for these two parent cats?
hhAA (Dad)
HHaa (Mom)
b. If the offspring of these two cats are allowed to freely interbreed, what will the
offspring (the ‘grandkittens’) be? (Show your work and provide both the expected
genotype and phenotype of the offspring!)
All offspring will be HhAa.
Punnett square)
Crossing two of these (use a standard dihybrid
1/16 HHaa
2/16 Hhaa
1/16 hhaa These four are all albino.
1/16 HHAA
2/16 HHAa
2/16 HhAA
4/16 HhAa These nine are all Agouti.
1/16 hhAA
2/16 hhAa
These three are solid brown.
9. Two sets of parents are concerned that their babies were accidentally switched in the
hospital. After hearing about your extensive experience with genetics in Atoms to
Ecosystems, they’ve asked you to help settle their fears by looking at the results of their blood
typing tests:
Tim: Type A
Steve: Type AB
Sue: Type O
Holly: Type O
Baby #1: Type A
Baby #2 Type O
Were these babies switched? How do you know? (Show your work!)
Yes! Baby number two cannot belong to Steve (IAIB) and Holly (ii). Their children will have
either type A (IAi) or type B (IBi) blood.
10. Ion exchange chromatography is a common technique for isolating proteins of interest.
Answer the following questions about this method.
A. What is the charge on the column for cation exchange chromatography? Draw a
picture to represent this column.
Column will be negatively charged! Picture should reflect negatively charged
beads…
B. What is the charge on the protein during the loading step of cation exchange if this
purification method is going to work? Explain and show the interaction between the
protein and your column.
The protein will need to be positively charged to bind to the beads. Drawing should
show this interaction on a molecular level.
C. Describe how and under what conditions you would elute your protein from the
cation exchange column.
High salt should displace your protein…
D. Brainstorm a method you might use to chemically lower the affinity of your protein for
the column other than salt.
There could be other methods, but pH would be a good choice. Reducing the
overall positive charge on the proteins by pulling off H+ will reduce its affinity for the
column.
11. Examine the following amino acid sequence for the GFP protein we’re using in lab this
week.
Note that the version you’re using has been deliberately altered to replace three amino
acids (phenylalanine-F, methionine-M, and valine-V) with three other amino acids
(serine-S, threonine-T, and alanine-A).
A. Examine the structures of the three amino acids that were replaced, along with the three
amino acids that were deliberately chosen to replace them. What differences do you
notice? How might these differences affect the overall structure of this version of GFP?
The largely nonpolar, hydrophobic amino acids were replaced with more polar,
hydrophilic amino acids. This should make the overall protein more hydrophilic.
B. Consider that this protein was designed to be over-expressed in E. coli. In other words,
scientists would like the transformed cells to large quantities of this recombinant protein.
How might the structural changes described above facilitate this over-expression?
There might be several good answers here…
This change will make the protein more water soluble. Thus the cells can produce and
store more of the protein in their aqueous cytoplasm.