Final Exam Flashcards
A given protein is 210 amino acids long. The mRNA encoding this protein is at least
630 nucleotides long
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?
Yy x yy
Primers are required for PCR because
DNA polymerases can add nucleotides to an existing strand of DNA, but cant initiate a strand
In Anaphase II, what separate
Sister chromatids
Given the coding DNA sequence 5’-TAC AAA ATA CAG CGG -3’, which of these sequences represents a nonsense mutation
5’ TAG AAA ATA CAG CGG 3’
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?
.2
A man is born with the karyotype 47, XYY. The most likely explanation for this is
Non disjunction during meiosis II in his fater
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?
Incomplete penetrance
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?
Fewer than four phenotypes
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?
Complementation occurred and the mutations are in two different genes
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
Pleiotropy
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?
1.25%
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
7%
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?
1:1:1:1
Nondisjunction during Meiosis I occurs when the ___ fail to separate, resulting in ___ gametes that are abnormal
Homologs, 4
Which of the following types of inheritance have the feature that an affected male has all affected daughters but no affected sons?
X linked dominant
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
5%
When two genes are in very close proximity in a chromosome, the probability of recombination is
very low
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?
DNA ligase
Which of the following is true for bacteria but not eukaryotes
mRNA molecules commonly contain information for several polypeptide chains
A mRNA is translated ____; polypeptide synthesis begins at the ___ and ends at the ___ end
5’ to 3’
amino
carboxyl
A primary RNA transcript contains 6 exons and is translated into several different protein products because of
Alternative splicing
Which of these haploid strians produce B-gal contitutively but do not produce permease?
I- P+ O+ Z+ Y-
Which of the following best describes the biological role of the lac operon?
It ensures that a cell produces enzymes involved in lactose metabolism only when lactose is available in the environment
Which of the following are cis acting in the lac operon?
Lac Oc and lac P-
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
trans-acting
Which evolutionary process involves the slow addition of allelic variation that increases the hereditary diversity of populations?
mutation
Which of the following is a basic assumtion underlying Hardy-Weinberg equilibrium?
Random mating occurs in the population
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
Founder effect
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?
Bottleneck effect
In a population, what is the consequence of inbreeding?
Inbreeding increases the frequency of homoztgotes and decreases the frequency of heterozygotes
