Final Exam

Question 1

A given protein is 210 amino acids long. The mRNA encoding this protein is at least

Answer 1

630 nucleotides long

Question 2

In peas, the yellow allele is dominant over the green allele. If a plant with yellow peas is crossed to a plant with green peas, the resulting plants are 50% yellow and 50% green. What is the genotype of the parents in this cross?

Answer 2

Yy x yy

Question 3

Primers are required for PCR because

Answer 3

DNA polymerases can add nucleotides to an existing strand of DNA, but cant initiate a strand

Question 4

In Anaphase II, what separate

Answer 4

Sister chromatids

Question 5

Given the coding DNA sequence 5’-TAC AAA ATA CAG CGG -3’, which of these sequences represents a nonsense mutation

Answer 5

5’ TAG AAA ATA CAG CGG 3’

Question 6

For linked genes A,B,C the map distance a-b is 5 mu and the distance b-c is 25 mu. If there are 10 double crossover events out of 1000 offspring, what is the interference?

Answer 6

.2

Question 7

A man is born with the karyotype 47, XYY. The most likely explanation for this is

Answer 7

Non disjunction during meiosis II in his fater

Question 8

Most people with the dominant mutant polydactyly allele have extra digits, but at least 25% have the normal number of digits. What is the genetic explanation for this observation?

Answer 8

Incomplete penetrance

Question 9

Independent assortment predicts a 9:3:3:1 ratio with four different phenotypes in the F2 progeny. If the alleles are epistatic what would you predict?

Answer 9

Fewer than four phenotypes

Question 10

Two pure breeding mutant plants produce white flowers. When they are crossed, all of the progeny have wild type purple flowers. How can this data best be interpreted?

Answer 10

Complementation occurred and the mutations are in two different genes

Question 11

Cystic fibrosis is caused by mutation of a gene encoding a membrane channel protein. Mutant alleles affect many organs and cause a variety of seemingly unrelated symptoms. This is an example of

Answer 11

Pleiotropy

Question 12

Genes X,Y, and Z are linked. Crossover gametes between genes X and Y are observed with a frequency of 25% and crossover gametes between genes Y and Z are observed with a frequency of 5%. What is the expected frequency of double crossover gametes among these genes?

Answer 12

1.25%

Question 13

Genes A and B are 14 map units apart. In a cross Ab/aB x ab/ab, what fraction of the progeny is expected to be AB/ab

Answer 13

7%

Question 14

In a two point test cross involving unlinked genes, what phenotypic ratios would be expected from a cross between a dihybrid female and homozygous recessive male?

Answer 14

1:1:1:1

Question 15

Nondisjunction during Meiosis I occurs when the ___ fail to separate, resulting in ___ gametes that are abnormal

Answer 15

Homologs, 4

Question 16

Which of the following types of inheritance have the feature that an affected male has all affected daughters but no affected sons?

Answer 16

X linked dominant

Question 17

The genes A and B are 10 mu apart. In a cross AB/ab x ab/ab what fraction of the progeny is expected to be Ab/ab

Answer 17

5%

Question 18

When two genes are in very close proximity in a chromosome, the probability of recombination is

Answer 18

very low

Question 19

In a temperature sensitive mutant strain of E. coli, Okazaki fragments accumulate and DNA synthesis is never completed. What is the enzyme or function likely affected in this strain?

Answer 19

DNA ligase

Question 20

Which of the following is true for bacteria but not eukaryotes

Answer 20

mRNA molecules commonly contain information for several polypeptide chains

Question 21

A mRNA is translated ____; polypeptide synthesis begins at the ___ and ends at the ___ end

Answer 21

5’ to 3’
amino
carboxyl

Question 22

A primary RNA transcript contains 6 exons and is translated into several different protein products because of

Answer 22

Alternative splicing

Question 23

Which of these haploid strians produce B-gal contitutively but do not produce permease?

Answer 23

I- P+ O+ Z+ Y-

Question 24

Which of the following best describes the biological role of the lac operon?

Answer 24

It ensures that a cell produces enzymes involved in lactose metabolism only when lactose is available in the environment

Question 25

Which of the following are cis acting in the lac operon?

Answer 25

Lac Oc and lac P-

Question 26

A mutation on the lac I gene (which produces the repressor protein) is likely to have a ____ effect on transcription of the lac operon structural gnees

Answer 26

trans-acting

Question 27

Which evolutionary process involves the slow addition of allelic variation that increases the hereditary diversity of populations?

Answer 27

mutation

Question 28

Which of the following is a basic assumtion underlying Hardy-Weinberg equilibrium?

Answer 28

Random mating occurs in the population

Question 29

All old order amish families from lancaster county with ellis-van creveld syndrome can trace their genealogies to Mr. and Mrs. Samuel King, who immigrated to lancaster county in 1744. This is an example of

Answer 29

Founder effect

Question 30

Cheetahs exhibit significant inbreeding and loss of heterozygosity due to overhunting and loss of habitat experienced at some point in their evolutinoary histroy. Which genetic mechanism occurs when a large population is substantially reduced at random, acting independently of natural selection?

Answer 30

Bottleneck effect

Question 31

In a population, what is the consequence of inbreeding?

Answer 31

Inbreeding increases the frequency of homoztgotes and decreases the frequency of heterozygotes