Crossing over between homologous chromosomes occurs at which of the following stages of meiosis?
C. prophase I
The map of a chromosome interval is Q 10 R 40S. Which interval would likely show the higher ratio of double to single chiasmata?
D. R-S
Suppose a three-point testcross was conducted involving the genes X, Y, and Z. If the most abundant classes are XYZ and xyz and the rarest classes are XyZ and xYz, which gene is in the middle?
B. Y
Alternative resolution of the Holliday intermediate are responsible for whether or not crossing over occurs.
a. True
b. False
a. True
DNA replication occurs through a ___ process.
A. semiconservative
The term mutation refers to
C. a heritable change in the DNA of a cell
In animal gametogenesis, a single primary spermatocyte generates ____ sperm, while a single primary oocyte generates ______ egg(s).
A. 4,1
A female that is XXO has Turner Syndrome.
a. True
b. False
b. False
In tetrad analysis, NPD asci result from
C. independent assortment of unlinked genes or double crossovers between linked genes
A hypothesis that predicts no linkage between genes is called the ___ hypothesis.
B. null
The ratio of ___ is 1:1.
C. adenine to thymine
A cross between a white-eyed female fruit fly and a red-eyed male would generate which of the following types of progeny?
B. The result cannot be predicted because it depends on whether the female is homozygous or heterozygous.
Recombination frequencies near 50% suggest that
B. two genes are on different chromosomes, or two genes are on the same chromosome but lie very far apart
Crossing over takes place in tetrads consisting of ____ chromatids, and involves ___ of the chromatids.
A. 4,2
Meselson and Stahl relied on equilibrium density gradient centrifugtion in a ___ solution to resolve the DNA containing 14N from the DNA containing 15N.
B. cesium chloride
How many replication forks depart from an origin of replication?
E. two
Which of the following terms describes the mutation of a mutant allele to a wild-type allele?
C. back mutation
Nondisjunction can occur at either the first or second division of meiosis. XYY individuals would most likely arise from nondisjunction at the meiotic division in the ____.
B. second, father
Which of the following processes can generate recombinant gametes?
A. crossing over between 2 linked heterozygous loci and independent assortment of 2 unlinked heterozygous loci
Ascospores are haploid cells that can germinate, replicate by mitosis, and survive as haploid individuals.
a. True
b. False
a. True
recombination involves the breakage and reunion of DNA molecules from
A. homologous nonsister chromatids
The protein that progressively unwinds DNA ahead of each replication fork is called
d telomerase
e. ligase
C. helicase
Red green color blindness is controlled by an X chromosome gene in humans. A normal man and normal woman whose fathers are both color blind marry. What is the probability that their first child will be color blind?
D. 1/4
If the map distance between genes A and B is 10map units and the map distance between genes B and C is 25 map units, what is the map distance between A and C?
B. either 15 map units or 35 map units, depending on the order of the genes
A tetrad that contains all recombinant class haploid cells is known as a parental ditype.
a. True
b. False
b. False
Which of the following is NOT involved in ensuring the accuracy of a cell's genetic information?
B. ligases
Eukaryotic chromosomes have evolved special structures at the ends of chromosomes to ensure the replication of the two ends of linear chromosomes. These structures are called
B. telomeres
A missense mutation is one that creates a premature stop codon.
a. True
b. False
b. False
What type of chromosome provides the basis for sex determination in many sexually reproducing organisms?
A. sex chromosomes
Humans have 22 pairs of autosomes plus one sex chromosome pair. How many autosomes are present in a normal human primary spermatocyte?
c. 46
A. 44
What happens physically during the process of crossing over?
C. Two homologous chromatids break and rejoin at precisely the same site along the chromosome so that there is no loss or gain of material on either product.
The enzymes able to relaz supercoils in DNA is called
B. topoisomerases
Which of the following scientists proposed early recombination models?
E. Holliday
The cells in which meiosis occurs in males is referred to as
D. spermatocytes
Pyrimidines are a nitrogenous base containing a double ring, while purines contain a single ring.
a. True
b. False
b. False
Which of the following proteins is needed to lay down a segment of RNA complementary to the DNA before replication can proceed?
a. DNA polymerase I
d. DNA polymerase II
c. DNA polymerase III
d. primase
d. primase
Males with one copy of an X-linked gene are said to be ___ for that gene.
E. hemizygous
____ bonds are responsible for the chemical affinity between A and T (or G and C) nucleotides.
E. hydrogen
In tetrad analysis, the criterion for linkage of two genes is
E. PD>NPD
Which of the following is not an element found in DNA?
E. sulfur
Without ____ regions on the DNA during recombination, gene conversion could not occur.
B. heteroduplex
Premeiotic germ cells that divide mitotically in females are referred to as
E. oogonia
Hersey and Chase relied on ___ to physically separate the infected bacterial cells from the phage coats.
E. centrifugation
If 40% of the bases in a region of the mouse genome are cytosine, what percentage in that region are adenine?
