Genetics Exam #2
According to Chargaff's rule, if the DNA of a species contains 20% adenine, what percent of guanine will it contain? Select one: a. 30% b. 60% c. 20% d. 80% e. 40%
A
DNA and RNA polymerases add new nucleotides in what direction? Select one: a. 5' to 3' b. 3' to 5' c. Both directions
A
In DNA replication, which enzyme is responsible for the formation of the phosphodiester bonds that connect Okazaki fragments into a continuous strand? Select one: a. DNA ligase b. DNA polymerase c. Topoisomerase d. Exonuclease e. DNA primase
A
In bacterial DNA replication, which enzyme prevents supercoiling of the DNA ahead of the replication fork? Select one: a. Topoisomerase b. DNA ligase c. Helicase d. DNA polymerase e. Primase
A
In the Hershey and Chase experiment, T2 phages were labeled using either 35S for proteins or 32P for DNA, mixed with bacteria, and the mix placed in a blender and then centrifuged. Radioactive sulfur was found almost exclusively in the supernatant fraction, while radioactive phosphorus was found in the pellet fraction. This indicated that: Select one: a. phage DNA entered the cell, but the protein did not b. the phage did not infect the bacterial cell c. phage protein entered the cell, but the DNA did not d. both protein and DNA entered the cell
A
In the Meselson and Stahl experiments, bacterial cells were grown in 15N-containing media for several generations and then moved to 14N-containing media, resulting in the incorporation of the light 14N isotope into newly synthesized DNA during DNA replication. If DNA replication was conservative, after one round of replication in 14N, the density of the double stranded DNA would be: Select one: a. all intermediate (14N/15N) b. half heavy (15N/15N) and half light (14N/14N) c. all heavy (15N/15N) d. half intermediate (14N/15N) and half heavy (15N/15N)
A
The backbone of the DNA molecule is formed by ________. Select one: a. Phosphodiester bonds b. Pyrophosphate c. Nitrogenous bases d. Hydrogen bonds e. Peptide bonds
A
The purpose of DNA replication is to produce _____. Select one: a. two daughter strands b. two template strands c. two coding strands d. two parental strands e. none of the answers are correct
A
The use of the terms "leading" and "lagging" strands indicates that we are discussing which of the following cellular processes? Select one: a. DNA replication b. RNA processing c. Translation d. Protein modification e. Transcription
A
We wish to know the map distance between two genes in Drosophila. The first gene is vestigial wings (vg), which is recessive to normal wings (vg+). A second trait, brown eyes (bw) is recessive to normal eyes (bw+). A female fly who is heterozygous for these traits is crossed to a male fly who is homozygous recessive. The following offspring are produced: 92 vg+bw+ 154 vg+ bw 158 vg bw+ 96 vg bw When doing a chi square analysis to test for linkage, what is the expected number of offspring in each phenotypic class of this cross? Select one: a. 125 b. 62.5 c. 500 d. 93.75 e. can't be determined
A
Which of the four bases found in DNA is not found in RNA? Select one: a. Thymine b. Adenine c. Cytosine d. Uracil e. Guanine
A
Why is X-inactivation needed in humans? Select one: a. for dosage compensation b. to eliminate X-linked lethal alleles c. all the answers are correct d. to inactivate genes coming from one parent e. to protect against heterosis
A
You have calculated the interference value to a given mapping experiment to be 0.3 (30%). What does this mean? Select one: a. 30% fewer double crossovers occured than expected. b. 70% more double crossovers occured than expected. c. 70% fewer double crossovers occured than expected. d. 30% more double crossovers occured than expected.
A
____ and ____ represent a rearrangement of the genetic material within a single chromosome or between two chromosomes. Select one: a. Inversions, translocations b. Deletions, translocations c. Deletions, duplications d. Inversions, duplications e. Translocations, duplications
A
A loss of an internal piece of a chromosome is called a(n) ____. Select one: a. gene duplication b. interstitial deletion c. reciprocal translocation d. terminal deficiency e. pericentric inversion
B
Adenine and thymine form ___ hydrogen bonds between them, while cytosine and guanine form ____ bonds. Select one: a. 3, 2 b. 2, 3 c. 3, 3 d. 2, 2
B
Crossing over is more likely to occur between genes that are ______ on a chromosome. Select one: a. close together b. far apart
B
In Drosophila, a cross was made between females expressing three X-linked recessive traits, scute bristles (sc), sable body (s), and vermillion eyes (v), and wild type males (+ indicates wild type alleles). In the F1 generation, all females were wild type, while all the males expressed all three mutant traits. The cross was carried to the F2 generation and 1000 offspring were counted, with the following results. No determination of sex was made in the F2 generation. sc s v 314 sc s + 10 sc + + 156 sc + v 46 + s + 30 + s v 150 + + v 14 + + + 280 What is the proper order of the genes on the X chromosome? Select one: a. v - s - sc b. sc - v - s c. s - sc - v d. sc - s - v e. + - sc - v
B
In which of the following would you most likely find DNA sequences representing genes encoding proteins? Select one: a. Origins of replication b. Euchromatin c. Centromeric DNA d. Telomeric DNA e. Heterochromatin
B
Okazaki fragments are ________. Select one: a. used in dispersive DNA replication b. used in the synthesis of the lagging strand c. pieces of broken Japanese porcelain d. only found in prokaryotes e. made of RNA
B
The Hershey and Chase experiment determined that phage DNA enters the cell while phage proteins do not by subjecting cells to radiolabeled phages and placing them in a blender to shear off the phage particles attached to the outside of the cells. If the bacterial cell pellets from this experiment were incubated in an appropriate growth medium, what would most likely occur? Select one: a. Bacteria would survive as there is no proof they were infected with phage. b. Phage should be produced and kill the cells. c. The radioactive phosphate would kill the cells immediately. d. No phage would be produced as the protein coat was removed.
B
What is the molecular mechanism for imprinting a gene? a. acetylation b. methylation c. phosphorylation d. mutation e. nitration
B
Which of the following best describes the observations of Meselson and Stahl after 15N-labeled bacterial cells have replicated a second time in media containing 14N? Select one: a. A single band of 15N/14N (intermediate) b. Two bands, one each of 14N/14N (light) and 15N/14N (intermediate) c. A single band of 14N/14N (light) d. Two bands, one each of 14N/14N (light) and 15N/15N (heavy) e. Two bands, one each of 15N/14N (intermediate) and 15N/15N (heavy)
B
Which of the following is NOT involved in the compacting of bacterial DNA? Select one: a. Formation of loop domains b. Use of nucleosomes c. Supercoiling, formation of loop domains, and use of nucleosome are all used d. Supercoiling e. None of the answers are used for compacting bacterial DNA
B
Which of the following represents DNA that changes its level of compaction during different parts of the organism's development? Select one: a. All heterochromatin b. Facultative heterochromatin c. Telomeric DNA d. Euchromatin e. Constitutive heterochromatin
B
Which of the following was the key finding of Avery's work with Streptococcus pneumoniae based on Griffith's earlier discovery of the "transforming principle"? Select one: a. One gene codes for a single enzyme b. Griffith's transforming factor was DNA c. DNA is a double helix d. Proteins are the hereditary material e. Bacteriophages inject DNA into bacteria
B
Which of the following would not be needed in the replication of the leading strand? Select one: a. Helicase b. DNA ligase c. RNA primer d. DNA polymerase e. Free nucleotides
B
____ and ____ represent a change in the total genetic material of a chromosome. Select one: a. Deletions, translocations b. Deletions, duplications c. Inversions, duplications d. Inversions, translocations e. Translocations, duplications
B
A retrovirus (for example HIV) uses _____ as its genome. Select one: a. proteins b. cDNA c. RNA d. DNA e. RNA-DNA hybrid molecules
C
Histones are ________. Select one: a. Nasal decongestants b. Concretions associated with male kidneys c. Proteins associated with DNA d. Specialized RNA molecules e. Subatomic particles stabilizing DNA
C
In genetic mapping, a testcross is always performed between the individual that is heterozygous for the genes to be mapped and an individual who is ____________. Select one: a. Homozygous dominant for the genes b. Lacking the genes c. Homozygous recessive for the genes d. Heterozygous for the genes e. None of the answers are correct
C
In the Hershey and Chase experiment, bacterial cells were infected with T2 phage to show whether DNA or protein is responsible for transmitting the phage's genetic information into the bacterial cell. A modern experiment that confirms this experiment would be: Select one: a. prescribing enzyme pills to help cystic fibrosis patients with digestion b. consuming radioactive barium to view internal organs with X-rays c. injecting DNA into a cell which causes the cell to produce an enzyme it never had before d. fertilizing an egg with a sperm in vitro
C
In which structure is the bacterial chromosome located? Select one: a. Nucleosome b. Nucleolus c. Nucleoid d. Nuclein e. Nucleus
C
Individuals with three copies of most autosomes do not survive. Individuals with an extra X chromosome, however, survive with relatively mild (compared to autosomal abnormalities) consequences. Why? Select one: a. Because the X chromosome determines sex only. b. Because the X chromosome contains few genes while autosomes contain a large number. c. Because the extra X chromosome(s) are inactivated. d. None of the answers are correct. e. All of the answers are correct.
C
Monoallelic expression is usually associated with ____________ in diploid organisms. Select one: a. dominant epistasis b. dosage compensation c. genomic imprinting d. maternal effect e. extranuclear inheritance
C
The Hershey and Chase experiment used a blender to shear phage particles off the bacterial envelopes that they had attached to. A possible alternative to the blender technique used in this experiment would be: Select one: a. incubate bacteria with a mutant phage that could not bind to the cells b. break apart the cell membranes with a strong detergent c. shake the cell/phage mixture vigorously d. add a competitive inhibitor to the bacteria before adding phage
C
The majority of calico cats are female. However, a few rare males are observed. What is the genotype of a male calico cat? Select one: a. XbYY b. XBXb c. XBXbY d. XBY e. XBXBY
C
Where is extra nuclear DNA located in mammalian cells? Select one: a. Ribosomes b. Endoplasmic reticulum c. Mitochondria d. Lysosomes e. Chloroplasts
C
Which of the following best describes the observations of Meselson and Stahl after 15N-labeled bacterial cells have replicated a second time in media containing 14N? Select one: a. Two bands, one each of 14N/14N (light) and 15N/15N (heavy) b. A single band of 14N/14N (light) c. Two bands, one each of 14N/14N (light) and 15N/14N (intermediate) d. Two bands, one each of 15N/14N (intermediate) and 15N/15N (heavy) e. A single band of 15N/14N (intermediate)
C
Which of the following statistical tests is used to determine if two genes are linked or assorting independently? Select one: a. sum rule b. random sampling error c. chi square test d. product rule e. binomial expansion
C
A chromosome is stained with Giemsa stain and the banding pattern analyzed by a cytogeneticist. What would the nomenclature 3q23 mean in this analysis? Select one: a. associated with chromosome 23, long arm, band 3 b. associated with chromosome 23, short arm, band 3 c. associated with chromosome 3, short arm, band 23 d. associated with chromosome 3, long arm, band 23
D
A loss of an internal piece of a chromosome is called a(n) ____. Select one: a. terminal deficiency b. gene duplication c. pericentric inversion d. interstitial deletion e. reciprocal translocation
D
A significant change in chromosome structure is called a(n) _____. Select one: a. genome mutation b. polyploidy c. point mutation d. chromosome mutation e. allelic variation
D
As the replication fork moves down the DNA, what molecule leads the others? Select one: a. DNA polymerase b. single-strand binding proteins c. DNA ligase d. DNA helicase e. Primase
D
Chromosomes on a karyotype picture may be identified based on which of the following? Select one: a. size of the chromosome b. banding patterns c. location of centromere d. all of the answers are correct e. length of the arms
D
Genomic imprinting most commonly uses____ to ____genes. Select one: a. acetylation : activate b. methylation : activate c. phosphorylation : activate d. methylation : deactivate e. phosphorylation : deactivate
D
Histones are ________. Select one: a. Subatomic particles stabilizing DNA b. Concretions associated with male kidneys c. Nasal decongestants d. Proteins associated with DNA e. Specialized RNA molecules
D
In the Hershey and Chase experiment, T2 phages were labeled using either 35S for proteins or 32P for DNA, mixed with bacteria, and the mix placed in a blender and then centrifuged. Radioactive sulfur was found almost exclusively in the supernatant fraction, while radioactive phosphorus was found in the pellet fraction. This indicated that: Select one: a. phage protein entered the cell, but the DNA did not b. the phage did not infect the bacterial cell c. both protein and DNA entered the cell d. phage DNA entered the cell, but the protein did not
D
Water snails demonstrate maternal effect in the coiling of their shells. Gene product from the D (dextral) allele induces right coiling whereas gene product from the d (sinistral) allele induces left coiling. Where is the gene for shell coiling likely found? Select one: a. on the Y chromosome b. on the mtDNA c. on the X chromosome d. on an autosome e. on the cpDNA
D
Where is extra nuclear DNA located in mammalian cells? Select one: a. Lysosomes b. Chloroplasts c. Endoplasmic reticulum d. Mitochondria e. Ribosomes
D
Histone H1 is involved in the stable formation of ________. Select one: a. Nucleosome cores b. Sister chromatids c. Origins of replication d. Nuclear matrix e. Radial loop domains
E
Individuals with three copies of most autosomes do not survive. Individuals with an extra X chromosome, however, survive with relatively mild (compared to autosomal abnormalities) consequences. Why? Select one: a. Because the X chromosome contains few genes while autosomes contain a large number. b. None of the answers are correct. c. All of the answers are correct. d. Because the X chromosome determines sex only. e. Because the extra X chromosome(s) are inactivated.
E
Prader-Willi Syndrome and Angelman Syndrome are both associated with deletions of the same bands from the long arm of chromosome 15. However, their occurrence depends on whether the child inherited the defective chromosome from the mother or the father and the physical expression associated with each disorder is very different. This is an example of _____. Select one: a. sex-influenced inheritance b. heteroplasmy c. Mendelian inheritance d. nuclear inheritance e. genomic imprinting
E
Synthesis of new histones occurs during ________. Select one: a. G2 phase b. G0 phase c. G1 phase d. M phase e. S phase
E
The smallest genomes are found in the _____________. Select one: a. Animals b. Bacteria c. Plants d. Fungi e. Viruses
E
Which of the following proteins synthesizes short segments of RNA in DNA replication? Select one: a. DNA ligase b. Single-strand binding protein c. DNA helicase d. DNA polymerase e. Primase
E
While mapping two genes in Drosophila you observe 30 recombinants among 200 total offspring. What is the distance between these genes? Select one: a. 200 map units b. 3 map units c. 1.5 map units d. 30 map units e. 15 map units
E
