Genetics Exam Two

Restriction endonucleases: A. were identified as a defense mechanism against viruses by protists. B. are used to cut DNA or RNA at defined sequences. C. Recognize palindromic sequences and can be used to create pieces that are cohesive. D. All of the above. E. None of the above.

C. Recognize palindromic sequences and can be used to create pieces that are cohesive.

When two nucleotides are joined to each other: A. a phosphodiester bond is formed. B. a covalent bond is formed between the 3' alcohol group of the first nucleotide and the 5' phosphate of the second. C. a covalent bond is formed between the 5' alcohol group of the first nucleotide and the 3' phosphate of the second. D. A and B. E. A and C.

D. A and B. DNA is built using the exposed 3' alcohol

The term recombinant DNA means: A. DNA that has been engineered genetically. B. DNA that has been derived from two or more sources. C. DNA that has undergone homologous recombination. Correct! D. A and B. E. All of the above.

D. A and B. Engineered genetically generally means derived from several sources.

Suppose that protein had been found to be the hereditary material instead of DNA. How would the results of the Hershey-Chase experiment with T2 infection of E coli have differed? Most of the radioactive sulfur (35S) would have been found inside the infected cells. B. Most of the radioactive phosphorus (32P) would have been found associated with the phage ghosts outside the infected cells. C. Radioactive phosphorus (32P) would have been found equally distributed between the phage ghosts and the infected cells. D. Both A and B would have been observed. E. None of these would be observed

D. Both A and B would have been observed.

One of Chargaff's rules states that there is an equal number of purines & pyrimidines bases which means that: (A + C) = (G + T) (A + G) = (C + T). (G + C)= (A + T) (G + T)= (G + C)

(A + G) = (C + T). Equal number of purines (Adenine + Guanine) & pyrimidines (Cytosine + Thymine).

One species has 32 chromosomes and another species has 24 chromosomes. In an allotriploid of these two species, how many chromosomes would there be? 44 or 40 56 84 28 48 or 36

44 or 40

A diploid species has a total of 52 chromosomes. How many chromosomes would be found in a monosomy, trisomy, and autotriploid? 51; 78; 53 26; 53; 104 51; 53; 78 51; 53; 104

51; 53; 78

Gel electrophoresis separates DNA fragments according to size and: A. DNA moves through the gel toward the positive electrode. B. larger DNA fragments move more quickly than smaller fragments. C. fragments can be visualized by use of infrared light. D. All of the above. E. None of the above.

A. DNA moves through the gel toward the positive electrode.

When Watson and Crick were constructing their model of DNA, they used all of the following information EXCEPT: A. Linus Pauling's conclusion that hydrogen bonds held the bases together. B. Chargaff's rules, that the amount of adenine equaled the amount of thymine and the amount of cytosine equaled the amount of guanine. C. the width of the molecule, as determined by examining Dr. Franklin's X-ray crystallographic images. D. the spiral nature of the molecule, determined by those same images. E. Actually, they used all of this information.

A. Linus Pauling's conclusion that hydrogen bonds held the bases together. Linus Pauling determined that PROTEIN secondary structures were held together by hydrogen bonds.

Which one of the following genotypes is an inversion heterozygote? ABCD/abcd. ACBD/ACBD. ABCD/ACBD. AcbD/AcbD.

ABCD/ACBD.

Aberrant chromosomes that have no centromere are called: Dicentric. Metacentric. Acentric. Acrocentric.

Acentric.

Which of the following statement about RNA molecules is FALSE? Basic components of RNA are ribonucleotides All RNA molecules are always translated into proteins RNAs like all nucleic acids absorb UV light at 260nm DNA/RNA heteroduplexes can form through molecular hybridization when their sequences are complementary Most RNA molecules are usually single-stranded yet they may form double stranded secondary structures when their sequences are complementary, which are critical for their functions.

All RNA molecules are always translated into proteins

Autotriploids _____. can result from the fertilization of a haploid gamete with an abnormal diploid gamete can result from the fertilization of an egg by two haploid sperm can result from the crossing of a diploid with a tetraploid have three chromosome sets that are identical in terms of number and content all of the above

All of the above Autotriploids are formed from one parental species in one of several ways.

The series of transformation experiments performed by Avery McLeod, and McCarthy, and Griffith, demonstrated that: harmless bacteria could become pathogenic by picking up material from pathogenic strains. proteins did not serve as the molecule of heredity. RNA did not serve as the molecule of heredity. DNA served as the molecule of heredity. All of the above.

All of the above.

The proper genetic terminology to qualify a living organism that has gained or lost a chromosome is: Aneuploid. Triploid. Endopolyploid. Euploid.

Aneuploid.

The natural form of soluble DNA (in vivo) is: A-DNA. B-DNA. P-DNA. Z-DNA.

B-DNA.

The chemical composition of nucleotides includes all of the following EXCEPT: A. a sugar—ribose in the case of RNA. Correct! B. a sugar—ribose in the case of DNA. C. a phosphate. D. a nitrogenous base, adenine, cytosine, guanine, or thymine. E. Actually, all of these are parts of nucleotides.

B. a sugar—ribose in the case of DNA. DNA= deoxyribonucleic acid.

One of the most powerful relatively new techniques that has revolutionized much of genetic engineering by allowing amplification of sequences of DNA is: A. Restriction fragment length polymorphism (RFLP) analysis. B. Ligation based amplification (LBA). C. Reverse transcription chain amplification (RTCA). D. Polymerase chain reaction (PCR). E. None of the above.

D. Polymerase chain reaction (PCR). Reverse transcription is a real technique, but does not amplify DNA.

Which of the following is not included in the Watson-Crick model of DNA structure? A. It is composed of two strands. B. The two strands are held together by H bonds between nitrogenous bases. C. The resultant helix is right-handed. D. The strands run parallel. E. The helix has a constant diameter of 20 Å.

D. The strands run parallel.

Which of these enzymes catalyzes the phosphodiester link between the 3' OH and 5'P of adjacent deoxyribonucleotides on 2 successive Okasaki fragments? DNA polymerase I. DNA polymerase ε (epsilon) DNA ligase. DNA gyrase.

DNA ligase.

In the Hershey & Chase experiment, which molecule was labeled with the 32P radioisotope? Proteins. DNA. Sugars. Lipids. Ribosomes

DNA.

In an RNA strand, which of these molecules will NOT be present? Deoxyadenosine Guanosine. Adenylic acid. Adenosine. Uridine

Deoxyadenosine

Which of these proteins/enzymes are E. coli helicases that specifically unwind the double helix during DNA replication? DnaC/DnaB. DnaA/DnaG. DnaB/DnaE. All of the above.

DnaC/DnaB. after DnaA binds to specific sequence and promote binding by DnaC/DnaB helicases (ATP)

Which type of chromosome mutation causes the Bar eye phenotypes in Drosophila? Deletion. Translocation. Inversion. Duplication

Duplication

Which of these chromosomal mutations may arise because of unequal crossing over between homologous chromosomes during meiosis? Non reciprocal translocation. Inversion. Robertsonian translocation. Duplication.

Duplication.

The Hershey-Chase experiment demonstrated that: A. bacteria used DNA as the molecule of heredity B. bacteria did not use proteins as the molecule of heredity. C. viruses used proteins as the molecule of heredity. D. A and B E. None of the above.

E. None of the above.

Nondisjunction in the first meiotic division in a male human could result at fertilization in _____. (Assume that the female parent involved contributes a normal gamete). Jacob syndrome Turner syndrome Klinefelter syndrome Triplo X syndrome Either Turner or Klinefelter

Either Turner or Klinefelter Primary nondisjunction in a male human results in either a gamete with no sex chromosome (0) or a gamete with both an X and a Y chromosome (XY). At fertilization, they would combine with the egg's single X chromosome. This would result in either X0 Turner syndrome or XXY Klinefelter syndrome.

Which of these nucleic acid analysis techniques does not rely on molecular hybridization? Fluorescence In Situ Hybridization/FISH. Southern blot. Northern blot. Electrophoresis. Polymerase Chain Reaction

Electrophoresis. Electrophoresis separates nucleic acids (DNA or RNA) molecules by molecular weight in a gel matrix.

A plant that is triploid will likely experience a high frequency of aneuploidy and other improper chromosome segregation events during mitosis. True False

False

An amphidiploid is a fertile autotetraploid. True False

False It is a fertile ALLOtetraploid (result of hybridization between two close species followed by the doubling of chromosomes)

Inversions of segments of chromosomes involving the centromere region are called paracentric inversions. True False

False These are PERIcentric inversions.

DNA replication is semi conservative and bi-directional. The direction of the synthesis of the copied strand is always 3' to 5' True False

False DNA replication is semi conservative and bi-directional BUT the direction of synthesis is ALWAYS 5' to 3'

Okasaki fragments are generated on the leading strand during DNA replication. True False

False It is on the lagging strand.

The bipotential gonads of a 5-6 week old human embryo of XX genotype will later develop into: Male gonads. Female gonads. Both male and female gonads (hermaphrodite). None of these answers are correct.

Female gonads

Which one of these results from the presence of one bp (base pair) mismatch in a recombinant chromosome? Gene duplication. Gene conversion. Gene deletion. Gene silencing.

Gene conversion.

Which one of the following does NOT apply to the function or structure of telomeres? Chromosome protection and stability. Presence of G-rich repeats in one of the DNA strands. Heterochromatin. Gene-rich region.

Gene-rich region.

Which of these experimental steps was NOT performed in the Meselson-Stahl pulse-chase experiment? Sedimentation/density gradient. In vivo DNA labeling with 15N isotope. Bacterial liquid culture in minimum medium. In vivo DNA labeling with [3H]-thymidine.

In vivo DNA labeling with [3H]-thymidine.

Which statement best describes human sex determination? Females are heterogametic Individuals with a Y chromosome are male Individuals with two X chromosomes are female. Individuals with at least twice as many X chromosomes as Y chromosomes are female Individuals with one X chromosome are male.

Individuals with a Y chromosome are male

An extra Y chromosome in the karyotype of a human male results in which sex syndrome? Klinefelter syndrome Turner syndrome Jacob syndrome. Triplo X syndrome.

Jacob syndrome

One of the primary reasons some allopolyploid organisms are fertile and able to propagate is they reproduce only asexually they are normally haploids and don't have to solve the intricate chromosome sorting problems faced by organisms that go through meiosis. chromosome sets from each parent species present in the allopolyploid are able to go through synapsis and crossing over, with proper chromosome segregation, during meiosis. They have alternating haploid and diploid phases of their life cycle. none of the above.

chromosome sets from each parent species present in the allopolyploid are able to go through synapsis and crossing over, with proper chromosome segregation, during meiosis.

In a polymerized DNA strand, which types of nucleotides are present? dNMPs. dNDPs. dNTPs. NMPs. NTPs

dNMPs.

A triploid is euploid. aneuploid. not found in nature because it will always cause lethality. commonly found in many mammalian species.

euploid.

Dosage of some genes can be very important, and, in order to balance dosages of genes on sex chromosomes and autosomes, all of the following mechanisms are employed EXCEPT: increasing the number of sex chromosomes. increasing expression of genes on sex chromosomes. inactivating all but a single X chromosome. reducing expression of genes on autosomes. Actually, all of these are used by various organisms.

increasing the number of sex chromosomes.

Aneuploids of which chromosomes are less likely to result in a live birth? larger autosomes small autosomes sex chromosomes All of the above. None of the above.

larger autosomes

Polyploidy that occurs in nature is common in plants, absent in animals. always associated with sterility. associated with sterility in males, but females remain fertile. thought to be a driving force behind evolution, and is the basis for many examples of speciation. most common in traits that are polygenic.

thought to be a driving force behind evolution, and is the basis for many examples of speciation.

Inactivation of X chromosomes by mammals results in all of the following EXCEPT: production of Barr bodies. males and females producing different amounts of protein from genes on the X chromosome. dosage compensation. unpredictable patterns of expression of some genes. Actually, it results in all of these.

males and females producing different amounts of protein from genes on the X chromosome.

Any molecule that serves as the genetic material must have the following characteristics except _____. the ability to be replicated the ability to store information the ability to directly influence the development of traits the ability to express information the potential to be changed via mutation

the ability to directly influence the development of traits

Which one of these polymerases is an RNA-dependent polymerase? Pol α (alpha) Telomerase Pol ε (epsilon) Pol δ (delta)

Telomerase Telomerase is an RNA-dependent polymerase that uses its own RNA template to synthesize a complementary DNA sequence at the end of the telomeres (repeats).

Which of these chromosome mutations does NOT require 2 breaks on the same chromosome to happen? Terminal deletion Interstitial or intercalary deletion. Paracentric inversion. Pericentric inversion.

Terminal deletion

The SRY gene on chromosome Y in mammals encodes which one of these products? The Mullerian inhibiting substance (MIS). Testis determining factor (TDF). Estrogen. Testosterone.

Testis determining factor (TDF).

Some critical genes responsible for the development and function of the testes in mammals are found in which specific portion of the MSY region? The X-degenerative region. The ampliconic region. The X-transposed region. The heterochromatin region.

The ampliconic region.

During meiosis in mammals, the X and Y sex chromosomes pair together. During that process, they may synapse and recombine in which following homologous (= similar in sequence) region? The Male-specific region of the Y (MSY). The non pseudoautosomal region of the X (NPX). The pseudoautosomal regions (PAR). The centromere

The pseudoautosomal regions (PAR). The PAR regions are both in the telomere region (ends) of both the X and Y chromosomes. These regions have a high sequence of homology that allow synapsis & recombination without changing the characteristics of the two different sex chromosomes.

What was the MAIN reason why proteins were favored over DNA as the genetic information before the 1940s? Nucleic acids were not yet characterized. The tetranucleotide hypothesis. Proteins lacked diversity. Chromosomal theory.

The tetranucleotide hypothesis. The tetranucleotide hypothesis claimed that DNA lacked the genetic diversity necessary (only 4 nucleotides) to serve as genetic information. Proteins present in all parts of the cell seemed more diverse (20 amino acids).

During DNA replication, supercoiling of the DNA double-helix upstream of the replication fork is resolved by which type of enzyme? Primases. Helicases. Single-stranded binding proteins. Topoisomerases.

Topoisomerases.

The mechanism of DNA replication and repair through regions of DNA that are damaged or distorted is called: Recombination Translesion synthesis Gene conversion Reverse transcription

Translesion synthesis

Which one of these mutation heterozygotes will form unusual cruciform configurations during meiosis? Deletion heterozygote. Duplication heterozygote. Translocation heterozygote. Inversion heterozygote. Translocation heterozygote.

Translocation heterozygote.

Eukaryotic chromatin is characterized by the presence nucleosomes which are structures packaging DNA with several histone proteins. True False

True

Homologous DNA recombination involves the breaking, exchange and rejoining of DNA strands belonging to 2 nonsister chromatids. True False

True

Telomerase activity is high in malignant cancer cells, and almost inexistent in normal somatic cells. True False

True

The replisome is the enzyme complex that replicates DNA in eukaryotes, prokaryotes and viruses. It contains these enzymes and proteins: - Polymerase - Clamp & clamp loader. - Single stranded binding proteins - Primase & helicases True False

True

The most plausible explanation for why more human males are conceived than females is that _____. males produce more Y-bearing sperm than X-bearing sperm Y-bearing sperm are more viable than X-bearing sperm Y-bearing sperm are more motile than X-bearing sperm the female reproductive tract is less hospitable to X-bearing sperm the egg is more receptive to Y-bearing sperm

Y-bearing sperm are more motile than X-bearing sperm

In animals, heterozygosity for a large chromosomal inversion will most likely result in absence of crossing over at meiosis I within the inverted region a certain level of reduction in fertility. lethality. none of the above.

a certain level of reduction in fertility.

Trisomy is an example of euploidy. aneuploidy. triploidy. translocation.

aneuploidy.

In E. Coli, sites of initiation of DNA replication are called: Autonomously replicating sequences OriC. Consensus sequences. Replication forks.

OriC.

Which one of these enzymes is the E. coli DNA polymerase that has both 3'-5' and 5'-3' exonuclease activities (= vital for DNA replication fidelity)? Pol α (alpha) Pol I. Pol δ (delta) Pol III.

Pol I.

Which ones of these Eukaryotic polymerases possess a primase activity? Pol α (alpha) Pol γ (gamma) Pol ε (epsilon) Pol δ (delta)

Pol α (alpha)

Which ones of these eukaryotic polymerases does NOT have a 3'-5' exonuclease activity? Pol α (alpha) Pol γ (gamma) Pol ε (epsilon) Pol δ (delta)

Pol α (alpha)

Which of these polymerases is specifically involved in the DNA polymerization of the lagging strand in eukaryotes? Pol III. Pol α (alpha). Pol ε (epsilon) Pol δ (delta)

Pol δ (delta) PolIII: E. coli polymerase, Pol alpha= Synthesizes the RNA primers on both leading and lagging strands; Pol epsilon= involved in synthesis of LEADING strand

A gene whose sequence has degenerated through the course of evolution to a point that it has become non-functional is called: Transgene. Pseudogene. Eugene. Oncogene

Pseudogene.

Which mode of DNA replication produces hybrid strands (a double helix formed by an old strand & a newly synthesized strand)? Conservative. Semi-conservative. Dispersive. None of the above.

Semi-conservative.