Genetics Exam 3 Practice Test 50 Questions with Verified Answers
Gene conversion results from
A. Discontinuous replication
B. Photoreactivation
C.
... [Show More] Mismatch repair
D. Gap Repair
E. C and D - CORRECT ANSWER E. C and D
The picture below is two Holliday junctions in a pair of DNA molecules undergoing recombination Breakage and rejoining of the strands indicated by the arrows () and () results in crossover.
A. 1 and 2
B. 2 and 3
C. 3 and 4 - CORRECT ANSWER B. 2 and 3
In eukaryotic chromosome, the second level of compaction is the formation of
A. nucleosome
B. 30 nm fiber
C. 300 nm fiber
D. Chromatid
E. heterochromatin - CORRECT ANSWER 30 nm fiber
Which of the following is NOT included in core particle
A. H1
B. H2A
C. H2B
D. H3
E. H4 - CORRECT ANSWER H1
Histone proteins contain high amounts of amino acids..
A. Arginine and lysine
B. Glutamic acid and aspartic acid
C. Glycine and alanine
D. Tyrosine and phenylalanine
E. Cysteine and methionine - CORRECT ANSWER Arginine and lysine
Which of the following is (are) NOT true?
A. The modifications of the histone tails are important to gene activity
B. Part of compaction of the circular bacterial chromosome results from supercoiling
C. In highly condensed eukaryotic chromosomes, the radial loops are anchored to a scaffold.
D. All of the above
E. none of the above - CORRECT ANSWER E. None of the above
How many polypeptide chains are present in each nucleosome?
A. 5
B. 6
C. 8
D. 9
E. 10 - CORRECT ANSWER D. 9
Which of the following is (are) true?
A. Telomerase overcomes telomere shortening and the end-replication problem
B. The protein component of telomerase has the reverse transcriptase activity
C. Telomerase is expressed by embryonic stem cells and cancer cells.
D. All of the above
E. None of the above - CORRECT ANSWER D. All of the above
A chromosome with its centromere in the middle is..
A. submetacentric
B. metacentric
C. Acrocentric
D. telocentric
E. Holocentric - CORRECT ANSWER B. metacentric
In some cancer cells, there is an over expression of HDAC (histone deacetylase). What could be the possible consequence of HDAC over expression?
A. Increased acetylation of histones
B. Condensation of chromatin structure
C. Weak histone-DNA association
D. Activation of transcription - CORRECT ANSWER B. Condensation of chromatin structure
The karyotype shown is associated with which of the following genetic disorders?
A. Down syndrome
B. Turner syndrome
C. Klinefelter's syndrome
D. Cri du chat
E. Jacobs syndrome - CORRECT ANSWER A. Down syndrome
If one of the parents is a 14/21 translocation carrier, ( ) of the offspring would be viable
A. 1/2
B. 1/3
C. 1/4
D. 1/5 - CORRECT ANSWER A. 1/2
If one of the parents is a 14/21 translocation carrier, () of the viable offspring would have Down Syndrome
A. 1/2
B. 1/3
C. 1/4
D. 1/5 - CORRECT ANSWER A. 1/2
If one of the parents has a trisomy 21, the probability that their child will inherit Down syndrome is ()
A. 1/2
B. 1/3
C. 1/4
D. 1/5 - CORRECT ANSWER C. 1/4
A chromosome in which the linear order of a group of genes is the reverse of the normal order, has
A. duplication
B. deletion
C. translocation
D. inversion
E. Position effect variegation - CORRECT ANSWER D. inversion
Some XY individuals are phenotypically females. What chromosomal abnormality could account for this?
A. Mosaicism
B. Dosage compensation
C. A deletion of the portion of Y-chromosome containing the testis-determining factor
D. Mitotic segregation
E. Fragile X syndrome - CORRECT ANSWER C. A deletion of the portion of Y-chromosome containing the testis-determining factor
47, XXY is a condition known as
A. Trisomy-X syndrome
B. Klinefelter syndrome
C. Turner syndrome
D. Double-Y syndrome
E. Fragile-X syndrome - CORRECT ANSWER B. Klinefelter syndrome
Turner syndrome is the result of
A. Trisomy of the X chromosome
B. The presence of an extra Y chromosome
C. The absence of a Y chromosome
D. Monosomy of the X-chromosome
E. an extra chromosome number 18 - CORRECT ANSWER D. Monosomy of the X chromosome
Which of the following is (are) NOT true?
A. Heteroduplex refers to a duplex whose strands are derived from different sources, such as homologous chromosomes.
B. Amino acid sequences of histones are highly conserved across the species
C. In euchromatin, transcription is generally inactive (silent)
D. All of the above
E. None of the above - CORRECT ANSWER C. in euchromatin, transcription is generally inactive (silent)
An event in which the centromeric regions of two non-homologous acrocentric chromosomes become fused to form a singular centromere is known as
A. reciprocal translocation
B. nonreciprocal transversion
C. Robertsonian translocation
D. Louisian transloaction
E. inversion - CORRECT ANSWER C. robertsonian translocation
How many Barr bodies would be present in white blood cells of an individual with karyotype 48, XXYY?
A. 0
B. 1
C. 2
D. 3
E. 4 - CORRECT ANSWER B. 1
The "calico" pattern of coat coloration in female cats in an example of
A. random X chromosome inactivation
B. position effect variegation
C. endoreduplication
D. a reciprocal translocation
E. trisomy of the X chromosome - CORRECT ANSWER A. random X chromosome inactivation
Which of the following means "the first band in the second region of the long arm of chromosome 3"?
A. 3p21
B. 3q21
C. 1p23
D. 1q23
E. pter - CORRECT ANSWER B. 3q21
Which of the following general transcription factors has a helicase activity?
A. TFIIB
B. TFIID
C. TFIIC
D. TFIIE
E. TFIIH - CORRECT ANSWER E. TFIIH
Below is the structure of gene 1 and 2 in the chromosme. Which of the following is NOT true?
A. the anti-sense strand for gene 1 is the bottom strand of DNA
B. the coding strand for gene 2 is the top strand of DNA
C. the template strand for gene 1 is the bottom strand of DNA
D. The sense strand for gene 2 is the bottom strand of DNA - CORRECT ANSWER D. The sense strand for gene 2 is the bottom strand of DNA
In p-dependent termination, rut site in RNA acts as the binding site for
A. sigma factor
B. U-rich RNA sequence
C. p-protein
D. hairpin - CORRECT ANSWER C. p-protein
Which of the following is (are) NOT true?
A. the core promoter in eukaryotes is composed of the TATA box and a transcription start site.
B. E.coli promoters have conserved sequences as -10 and -35 nucelotide upstream of the transcription start site.
C. The general transcription factors are necessare for the assembly of a transcription apparatus and recruitment of RNA polymerase II to a core promoter
D. the regulatory elements are the binding site for specific transcription factors
E. none of the above - CORRECT ANSWER E. none fo the above
RNA is ysnthesized on a DNA template in a process called _____, which utilizes the enzyme ________.
A. translocation, RNA polymerase
B. transcription, DNA polymerase
C. transcription, RNA polymerase
D. replication, DNA polymerase - CORRECT ANSWER C. transcription, RNA polymerase
All eukaryotes have three different RNA polymerases which transcribe different types of genes. Which RNA polymerase transcribes protein-coding genes into mRNA in eukaryotes
A. RNA polymerase I
B. RNA polymerase II
C. RNA polymerase III - CORRECT ANSWER B. RNA polymerase II
Which of the following general transcription factor binds to DNA first during transcription initation?
A. TFIIB
B. TFIID
C. TFIIC
D. TFIIE
E. TFIIH - CORRECT ANSWER B. TFIID
The sigma factor protein's role in bacterial transcription includes which of the following?
A. helps the RNA polymerase to bind to the promoter
B. contributes to the proofreading activity of RNA polymerase
C. Required for continued extension of the RNA molecule
D. plays a role in transcription termination
E. all of the above - CORRECT ANSWER A. helps the RNA polymerase to bind to the promoter
Mutations in bacterial promoters may increase or decrease the level of gene transcription. Promoter mutations that increase transcription are termed up-promoter mutations, and those that decrease transcription are termed down-promoter mutations. The sequence of the -10 region of the promoter for the lac operon is 5'-TATGTT-3'. If the consensus sequence of the -10 region is 5'-TATGTT-3', which of the following would be the down-promoter mutation?
A. 5'-TATATT-3'
B. 5'-TATGAT-3'
C. 5'-TTTGTT-3'
D. A and C
E. A and B - CORRECT ANSWER C. 5'-TTTGTT-3'
Negatively charged phosphate groups in the
DNA backbone must be neutralized in order for the folding of DNA to occur. In bacterial DNA, this charge neutralization is carried out by a small positively charged molecules called polyamines. What proteins carry out this same function in eukaryotic cells?
A. Transcription factors
B. High mobility group proteins (HMG-1)
C. Histones
D. Scaffold proteins - CORRECT ANSWER C. Histones
Formation of D-loop (displacement loop) occurs during..
A. Mismatch repair
B. Gap repair
C. transcription
D. Site-specific recombination - CORRECT ANSWER B. Gap repair
A normal chromosome contains all but which of the following features?
A. 1 centromere
B. 8 telomeres
C. 9 histones per nucleosome
D. Heterochromatin - CORRECT ANSWER B. 8 telomeres
Which of the following is (are) NOT true?
A. chromosome painting allows the visualization of individual chromosmes
B. 3 largest human chromosomes (1,2, and 3) belong to Group A.
C. In about half of all spontaneous abortions, the fetus has a major chromosomal abnormality
D. 3-5% of Down syndrome cases involve a Robertsonian translocation between chromosomes 21 and 13.
E. TATA box is an example of cis-acting elements - CORRECT ANSWER D. 3-5% of Down syndrome cases involve a Robertsonian translocation between chromosomes 21 and 13.
Which histone protein is present as a monomer within the nucleosome?
A. H1
B. H2A
C. H2B
D. H3
E. H4 - CORRECT ANSWER A. H1
The DNA in the chromosome of E. coli is
A. linear
B. organized into a set of looped domains
C. clustered near the centromere
D. Associated with histones
E. positively supercoiled - CORRECT ANSWER B. organized into a set of looped domains
The C-value paradox refers to
A. The differences in the number of genes among different organisms.
B. high GC content in the genomes of some eukaryotes
C. the lack of correlation between genome size and the level of metabolic, developmental, and behavioral complexity among eukaryotes
D. the degree of condensation of the chromatin fibers within the nuclei of all eukaryotic cells - CORRECT ANSWER C. the lack of correlation between genome size and the level of metabolic, developmental, and behavioral complexity among eukaryotes
Which of the following is (are) NOT true?
A. The elementary unit of chromatin is the nucleosomal core particle, a tetramer of histone proteins around which is wrapped a length of duplex DNA
B. The telomere is a specialized DNA structure that serves to stabilize the chromosome tips from shortening through progressive loss of DNA
C. N-terminus of histone proteins is called a histone tail
D. In cells cycling through mitosis, the chromosme territories are disrupted when the chromosmes condense and the cell divides. - CORRECT ANSWER A. the elementary unit of chromatin is the nucleosomal core particle, a tetramer of histone proteins around which is wrapped a length of duplex DNA
What percentage of recognized pregnancies in humans terminates in spontaneous abortion
a. 50%
b. 15%
c. 1%
D. 5%
E. Less than 1% - CORRECT ANSWER B. 15%
Electrophoresis mobility shift (gel shift)/super shift assays are used to
A. determine DNA sequence
B. Study protein-DNA interactions
C. analyze protein composition
D. none of the above - CORRECT ANSWER B. study protein-DNA interactions
Which of the following is an example of viable human trisomy?
A. Trisomy 13
B. Trisomy 15
C. Trisomy 17
D. Trisomy 19 - CORRECT ANSWER A. Trisomy 13
Which of the following is (are) NOT true?
A. the normal female is a mosaic for X-linked genes.
B. The repositoning of a gene often affects its level of expression.
C. Karyotype refers to the number and type of chromosomes present in an individual
D. All of the above
E. None of the above - CORRECT ANSWER E. None of the above
The master sex-determining gene SRY resides on
A. The X chromosome
B. one of the autosomes
C. the pseudoautosomal region of the X chromosome
D. the pseudoautosomal region of the Y chromosome
E. in the short arm of the Y chromosome, but out of psuedoautosomal region - CORRECT ANSWER E. in the short arm of the Y chromosome, but out of psuedoautosomal region
Karyotype of a male with the Deletion in the long arm of chromosome 7 from q11.23 to q.21.2 is
A. 46, XX, (p11.23 p21.2)(7)
B. 46,XY, del (q11.23 q21.2)(7)
C. 46, XY, del (7) (q11.23 q.21.2)
D. 46, XX, (7)(q11.23 a 21.2) - CORRECT ANSWER C. 46, XY, del (7) (q11.23 q.21.2)
The cells used in the FISH technique are first arrested during
A. interphase
B. metaphase
C. telophase
D. prophase
E. anaphase - CORRECT ANSWER B. metaphase
Arrange the following in the proper sequence in which they occur during FISH
1. Denaturation of DNA
2. Addition of DNA probes
3. Fixation of chromosomes (Cells)
A. 1, 2, 3
B. 2, 1, 3
C. 2, 1, 1
D. 3, 2, 1
E. 3, 1, 2 - CORRECT ANSWER E. 3,1,2
Which of the following is (are) NOT true?
A. In addition to trisomy, triploids (3n=69) and tetraploids (4n=92) are also common in spontaneous abortions.
B. during crossover, 5' ends of broken DNA are precessed by exonucleases before 3' strand invasion
C. Monosomy is not found among aborted fetuses because the abortions take place so early in the development that the pregnancy goes unrecognized by the mother
D. All of the above
E. None of the above - CORRECT ANSWER
What is gene conversion?
A. a process by which a gene is rendered non-functional
B. A process that changes an allele to the allele existing on the homologous chromosome.
C. A process that restores the wild-type function of a gene
D. A process that creates a new allele of a gene
E. none of the above - CORRECT ANSWER B. A process that changes an allele to the allele existing on the homologous chromosome. [Show Less]