Genetics Exam 2

Select the statements that describe the effect of copy number variation on human phenotypes a. copy number variations are associated with complex disorder such as autism b. Increase in the copy number of genes involved in starch digestion allows for high-starch diet c. oncogene overexpression due to a gain in copy number can cause cancer d. a decrease in number can cause mendelian autosomal disorders due to point mutations e. an increase in number can cause gene function loss due to chromosome breaks

- copy number variations are associated with complex disorder such as autism - Increase in the copy number of genes involved in starch digestion allows for high-starch diet - oncogene overexpression due to a gain in copy number can cause cancer

tumor-suppressor genes typically act in a _______ manner, and oncogenes typically act in a _______ manner.

- recessive - dominant

proteins are composed of ______ linked together by _______

-amino acids -peptide

Select the statements that explain why duplication is the driving force for evolution and the generation of new genes. a. duplication of gene segment always results in novel gene function b. genes duplicate and the diverge from the original sequence to create novel genes c. duplicated genes provide extra copies of DNA that are not constrained by an essential function d. phenotypic variations can occur when random fixed mutations are introduced into a new chromosomal environment

-genes duplicate and the diverge from the original sequence to create novel genes -duplicated genes provide extra copies of DNA that are not constrained by an essential function -phenotypic variations can occur when random fixed mutations are introduced into a new chromosomal environment

____ is a type of polyploidy that arises from the hybridization between two different species. a. Paracentric inversion b. Allopolyploidy c. Autopolyploidy d. Tetrasomy

Allopolyploidy

Failure to separate for homologous chromosomes or sister chromatids is referred to as _____ a. Robertsonian translocation b. Gene dosage effect c. Nondisjunction d. Pseudodominace

Nondisjunction

Which statement about polyploidy is not true? a. Polyploidy is found in many of the food crop plants we enjoy, such as bananas and strawberries b. Polyploid often results in larger cell size c. Polyploidy results from failure to separate a whole set of chromosomes during cell division d. Polyploidy is a major mechanism by which new plant species have evolved e. Polyploidy is possible only between the members of the same species

Polyploidy is possible only between the members of the same species

Of all cases of primary down syndrome, 92% is due to _____ of chromosome 21. a. Nullisomy b. Trisomy c. Monosomy d. Tetrasomy

Trisomy

Whereas bacterial cells typically possess only one type of RNA polymerase, most eukaryotic cells possess ___ distinct types of RNA polymerase. a. 3 b. 7 c. 12 d. 4 e. 2

a. 3

Which is not a type of pre‑mRNA processing in eukaryotes? a. 3' mRNA degradation b. splicing c. RNA editing d. polyadenylation e. 5' cap addition

a. 3' mRNA degradation

Select the definition of euploidy a. A complete chromosome set or an exact multiple of the haploid chromosome set b. The number of chromosome sets that make up a complete genome c. The addition or loss of less than full set of chromosomes or chromosome pairs d. A chromosomal complement with at least three complete sets of homologous chromosomes

a. A complete chromosome set or an exact multiple of the haploid chromosome set

Which of these statements describe mosaicism? a. A tortoiseshell cat has patches of orange and black fur b. A cancerous tumor develops in a woman's ovary c. a wheel-chair bound person's leg muscles are weaker than her arm muscles d. the skin on a person's face and arms becomes much darker than the skin on the rest of the body after a summer of working outdoors e. a child with the phenotypic features a characteristic of Turner syndrome has a mixture of normal cells and cells with one copy of the x chromosome

a. A tortoiseshell cat has patches of orange and black fur b. A cancerous tumor develops in a woman's ovary e. a child with the phenotypic features a characteristic of Turner syndrome has a mixture of normal cells and cells with one copy of the x chromosome

A geneticist isolates a new restriction enzyme from the bacterium Aeromonas ranidae. No other restriction enzymes have been isolated from this bacterial species. Use the standard convention for abbreviating restriction enzymes to name this new restriction enzyme. a. AraI b. AeroI c. A.RaniI d. IAra e. Aeromonas I

a. AraI

What property of the DNA molecule explains the necessity for Okazaki fragments? a. DNA is antiparallel. b. DNA is wound around histones. c. DNA is negatively charged. d. DNA is a linear molecule.

a. DNA is antiparallel.

Why is a cap added to mRNA, but not to tRNA or rRNA? a. Each of the three types of RNA are transcribed by different RNA polymerases. Only RNA polymerase II, involved in mRNA synthesis, contains a domain capable of interacting with enzymes that form the cap. b. Only mRNA contains introns. Capping occurs simultaneously with intron removal because the same enzymes and proteins involved in both of these processes must bind to RNA at the same time. c. Transcription and processing of mRNA occur in the nucleus, where cap binding proteins are found. These proteins, which add and modify the cap, are not found in the cytoplasm, where tRNA and rRNA are transcribed and processed. d. Transfer RNA and rRNA exhibit complex structures with double stranded regions. The three-dimensional shapes of these molecules keep the 5' end of the RNA away from the enzymes that process the cap.

a. Each of the three types of RNA are transcribed by different RNA polymerases. Only RNA polymerase II, involved in mRNA synthesis, contains a domain capable of interacting with enzymes that form the cap.

During meiosis, errors can be made during chromosome replication. Which term describes a mutation where a chromosome breaks, and its genetic material is reinser different orientation? a. Inversion b. Duplication c. Frameshift d. Dicentric chromosome

a. Inversion

Select each of the characteristics that are key features of genetic material. a. It must be able to replicate and transmit to progeny b. It must periodically mutate to generate variation c. It must differentiate in each cell type d. It must be able to store and express information e. It must have observable characteristic that are heritable

a. It must be able to replicate and transmit to progeny b. It must periodically mutate to generate variation d. It must be able to store and express information

Which statement describes the conservative model of DNA replication correctly? a. It proposes that the entire double‑stranded DNA molecule serves as a template for a whole new molecule of DNA. b. It proposes that both nucleotide strands break down into fragments, which then serve as templates for the synthesis of new DNA molecules. c. It proposes that the two nucleotide strands unwind and each serves as a template for a new DNA molecule.

a. It proposes that the entire double‑stranded DNA molecule serves as a template for a whole new molecule of DNA.

Which of the statements describes purines and pyrimidines in DNA molecules? Select all that apply a. Purines form hydrogen bonds with pyrimidines. b. Thymine and cytosine are purines. c. Pyrimidines form hydrogen bonds with pyrimidines. d. Purines form covalent bonds with pyrimidines. e. Purines consist of a two-ring structure.

a. Purines form hydrogen bonds with pyrimidines. e. Purines consist of a two-ring structure.

What happens during the elongation step of DNA transcription? a. RNA polymerase moves along the template strand of the DNA creating an mRNA strand. b. A ribosome attaches to the initiation codon of a completed mRNA strand. c. A portion of the DNA unwinds and RNA polymerase attaches to the DNA within the transcription bubble. d. The mRNA detaches from the RNA polymerase as the RNA polymerase leaves the DNA strand.

a. RNA polymerase moves along the template strand of the DNA creating an mRNA strand.

Identify the key structural features of a DNA molecule. Select all that apply a. The backbone of DNA is made of a sugar and a phosphate molecule. b. DNA is most often found as a left-handed helix, commonly referred to as Z‑DNA. c. DNA strands are antiparallel and include a 5′ end and a 3′ end. d. Strong ionic bonds and hydrophobic interaction hold DNA together. e. DNA contains the nucleotide bases adenine, thymine, guanine, cytosine, and uracil. f. DNA bases are always paired using Watson-Crick base are always paired purine with pyrimidine.

a. The backbone of DNA is made of a sugar and a phosphate molecule. c. DNA strands are antiparallel and include a 5′ end and a 3′ end. f. DNA bases are always paired using Watson-Crick base are always paired purine with pyrimidine.

The Meselson and Stahl experiment starts with E. coli containing 15N/15N labeled DNA grown in 14N media. Which result did Meselson and Stahl observe by sedimentation equilibrium centrifugation to provide strong evidence for the semiconservative model of DNA replication? a. The first generation has hybrid 15N/14N DNA and the second generation has both hybrid 15N/14N DNA and 14N/14N DNA. No 15N/15N DNA was observed. b. The first generation has hybrid 15N/14N DNA and the second generation has hybrid 15N/14N DNA. No 15N/15N DNA nor 14N/14N DNA was observed. c. Both the first and second generation have both 15N/15N DNA and 14N/14N DNA. No hybrid 15N/14N DNA was observed.

a. The first generation has hybrid 15N/14N DNA and the second generation has both hybrid 15N/14N DNA and 14N/14N DNA. No 15N/15N DNA was observed.

Which statements about primers are correct? a. They provide a 3'−OH group for attachment of DNA nucleotides. b. They are needed for the start of DNA synthesis. c. They are synthesized by DNA polymerase α. d. They are synthesized by an enzyme called primase.

a. They provide a 3'−OH group for attachment of DNA nucleotides. b. They are needed for the start of DNA synthesis. c. They are synthesized by DNA polymerase α. d. They are synthesized by an enzyme called primase.

A left‑handed form of DNA is the a. Z‑DNA. b. A‑DNA. c. H‑DNA. e. B‑DNA.

a. Z‑DNA.

What is a purine? Select all that apply. a. a base with two rings b. a nucleoside c. adenine or guanine d. a base with one ring e. cytosine or uracil

a. a base with two rings c. adenine or guanine

which of the mutations described have the potential to cause cancer? a. a gain -of- function mutation in a proto-oncogene b. a loss -of- function mutation in a proto-oncogene c. a loss -of- function mutation in a tumor suppressor gene d. a gain -of- function mutation in a tumor suppressor gene

a. a gain -of- function mutation in a proto-oncogene c. a loss -of- function mutation in a tumor suppressor gene

Which of the techniques are examples of biotechnology? a. breeding different dog breeds for hunting or racing b. using transgenic microbes to break down pollutants in waste management c. using bacteria to convert milk to dairy products like butter, cheese, or yogurt d. using viral DNA to harvest viral proteins for use in vaccines

a. breeding different dog breeds for hunting or racing b. using transgenic microbes to break down pollutants in waste management c. using bacteria to convert milk to dairy products like butter, cheese, or yogurt d. using viral DNA to harvest viral proteins for use in vaccines

How do viruses contribute to cancer? a. by inactivating tumor suppressor genes b. by decreasing the expression of cellular oncogenes c. by driving over-expression of a cellular proto-oncogene d. by increasing the expression of genes that inhibit cell division e. by increasing the expression of DNA repair genes

a. by inactivating tumor suppressor genes c. by driving over-expression of a cellular proto-oncogene

Frequently, important DNA regions with specific functions tend to contain short stretches of nucleotides that are conserved across different organisms (e.g., promoter sequence) and are recognized by specific proteins. What are these conserved sequences called? a. consensus sequences b. critical elements c. initiators d. codons e. repetitive sequences

a. consensus sequences

Identify examples of reverse genetics. a. gene knockout using site‑directed mutagenesis b. mutation from wild‑type allele to mutant allele c. RNA interference d. mutation from mutant allele to wild‑type allele e. two‑hybrid test

a. gene knockout using site‑directed mutagenesis c. RNA interference

In eukaryotic cells, promoter consensus sequences are recognized by accessory proteins that recruit a specific RNA polymerase. Which of the types of accessory proteins serve this purpose? a. general transcription factors b. single‑strand‑binding proteins c. enhancer d. transcription repressors e. transcription activators

a. general transcription factors

Why can alternative splicing of messenger RNAs (mRNAs) be advantageous for eukaryotic organisms? a. increases the variety of proteins that can be produced b. allows for smaller genomes than prokaryotes c. decreases the average gene length in eukaryotes d. allows exons from two different genes to be spliced into a new mRNA e. removes exons instead of introns from newly transcribed mRNA

a. increases the variety of proteins that can be produced

Which of the following statements describes the function of the sigma factor in prokaryotic transcription? a. it facilitates the binding of RNA polymerase to the promoter to initiate transcription b. it catalyzes the synthesis of mRNA in a 5' to 3' direction to implement transcription elongation c. it causes the RNA polymerase to dissociate from the mRNA to terminate transcription d. it catalyzes the removal of the introns to produce mature mRNA to terminate transcription e. it attaches the amino acid to its cognate tRNA to initiate translation

a. it facilitates the binding of RNA polymerase to the promoter to initiate transcription

Which class of RNA serves as the coding instruction read by the ribosome to produce a polypeptide chain? a. mRNA b. tRNA c. snRNA d. rRNA e. miRNA

a. mRNA

Which processes ensure the high accuracy of replication? a. proofreading b. nucleotide selection c. mismatch repair d. replication licensing e. linear replication

a. proofreading b. nucleotide selection c. mismatch repair

Recombinant DNA technology is a set of molecular methods used to isolate, manipulate, and study DNA. What does recombinant mean, in this case? a. that the DNA used is often derived from two or more sources and combined b. that the DNA used has undergone homologous recombination c. that the DNA used was edited using the CRISPR‑Cas system d. that the DNA used was cut with restriction enzyme or enzymes e. that the DNA used does not contain introns

a. that the DNA used is often derived from two or more sources and combined

In the Hershey-Chase experiment, DNA was demonstrated to be the genetic material because the 32P label for DNA localized to a. the bacterial pellet. b. the supernatant. c. the blender. d. the bacterial pellet and the supernatant. e. the bacteriophage coats.

a. the bacterial pellet.

What is the Shine-Dalgarno sequence? a. the ribosome binding site in bacterial RNA b. three nucleotides that code for a specific amino acid c. the sequence of nucleotides at the 5' end of the RNA molecule that codes for amino acids d. the sequence of nucleotides at the 3' end of the RNA molecule that does not code for amino acids e. the ribosome binding site in eukaryotic RNA

a. the ribosome binding site in bacterial RNA

Genes that normally produce factors that inhibit cell division are called a. tumor‑suppressor genes. b. proto‑oncogenes. c. malignant genes. d. attenuation genes. e. oncogenes.

a. tumor‑suppressor genes.

Which relations will be found in the percentages of bases of a double‑stranded DNA molecule? a. A+T=G+C b. (A+G)/(C+T)=1.0 c. A+G=C+T d. A/T=G/C e. A/C=G/T

b. (A+G)/(C+T)=1.0 c. A+G=C+T d. A/T=G/C

select the statements that accurately describe different ways that translocation could lead to cancer. a. A translocation breaks up a gene that encodes a protein required to pass through mitotic checkpoints. the resulting protein cannot function normally. b. A gene for a protein that is involved in a mitotic checkpoint is placed next to the regulatory sequence of a different gene. the gene is now expressed in response to different stimuli. c. The new sequence is added to a proto-oncogene. the modified gene now produces new protein that increases the rate of cell division d. A translocation breaks up the sequence of a gene for a protein that stimulates apoptosis. the resulting protein cannot function properly. e. A gene for a protein that stimulates apoptosis is placed next to a regulatory sequence that increases the expression of the gene

b. A gene for a protein that is involved in a mitotic checkpoint is placed next to the regulatory sequence of a different gene. the gene is now expressed in response to different stimuli. c. The new sequence is added to a proto-oncogene. the modified gene now produces new protein that increases the rate of cell division d. A translocation breaks up the sequence of a gene for a protein that stimulates apoptosis. the resulting protein cannot function properly.

According to the central dogma, double-stranded DNA serves as the template for the production of RNA during transcription. Which of the two DNA strands serves as the template for transcription? a. Both DNA strands serve as templates simultaneously for RNA polymerase, with continuous transcription on the leading strand and discontinuous transcription on the lagging strand. b. Either DNA strand may be used as a template by RNA polymerase, but a single DNA strand oriented in the 3'-5' direction is used as a template each time transcription occurs. c. The DNA strand oriented in the 5'-3' direction is the only template because only this strand contains the promoter sequences necessary to initiate transcription. d. The DNA strand oriented in the 5'-3' direction is the only template because RNA polymerase synthesizes only in the 5'-3' direction.

b. Either DNA strand may be used as a template by RNA polymerase, but a single DNA strand oriented in the 3'-5' direction is used as a template each time transcription occurs.

Identify the statements that are features of a promoter. a. In eukaryotes, the promoter is recognized by a sigma factor subunit, which must bind to the promoter before forming the preinitiation complex b. In prokaryotes, the promoter contains a-35 and -10 region upstream of the transcription start site c. In both prokaryotes and eukaryotes, the promoter is located in the 5' direction, upstream from the transcription start site d. In eukaryotes, the promoter often contains a TATA box, which is where the TATA-binding protein binds e. In eukaryotes, the promoter attracts the small and large ribosomal subunits with the help of initiation factors

b. In prokaryotes, the promoter contains a-35 and -10 region upstream of the transcription start site c. In both prokaryotes and eukaryotes, the promoter is located in the 5' direction, upstream from the transcription start site d. In eukaryotes, the promoter often contains a TATA box, which is where the TATA-binding protein binds

Which statement about RNA is not true? a. RNA typically consists of a single polynucleotide strand with distinct secondary structures b. RNA is a more stable molecule than DNA c. RNA possesses catalytic activity, which earned it the name "ribozyme" d. Uracil is found in RNA as one of the two pyrimidine nitrogenous bases e. RNA is thought to have dominated early life on earth, serving as both genetic information and as a catalyst

b. RNA is a more stable molecule than DNA

What does the term antiparallel mean? a. The strands separate in opposite directions. b. The 5' end of one strand is opposite the 3' end of the second strand. c. The 5' end of one strand is opposite the 5' end of the second strand. d. The strands run in the same direction. e. The strands run in opposite directions

b. The 5' end of one strand is opposite the 3' end of the second strand. e. The strands run in opposite directions

How might a mutation in a gene that regulates telomerase lead to cancer? a. The mutation could prevent telomerase from being expressed at all. b. The mutation could allow telomerase to be expressed when it should not be. c. The mutation could result in a nonfunctional telomerase protein. d. The mutation could cause telomerase to be expressed in germ cells and stem cells. e. The mutation could cause telomerase to be produced at abnormally low levels.

b. The mutation could allow telomerase to be expressed when it should not be.

How would the deletion of the Shine-Dalgarno sequence affect a bacterial mRNA? a. Transcription would not occur. b. Translation would not occur. c. DNA replication would not occur. d. Translation would occur at a slower rate. e. Transcription would occur at a slower rate.

b. Translation would not occur.

Which is not a way in which chromosome mutations could lead to cancer? a. Inversions cause breaks within a tumor‑suppressor gene. b. Translocation of a tumor‑suppressor gene to a new location puts it under the control of a strong promoter. c. Translocation of a proto‑oncogene to a new location puts it under the control of a strong promoter. d. Chromosome rearrangements create fusion proteins that are more active and upregulate cell division. e. Deletions can remove or inactivate tumor‑suppressor genes.

b. Translocation of a tumor‑suppressor gene to a new location puts it under the control of a strong promoter.

What is a codon? a. an mRNA nucleotide occurring every three nucleotides that wobbles b. a set of three mRNA nucleotides that codes for a specific amino acid c. a set of three DNA nucleotides that codes for a specific amino acid d. a set of three DNA nucleotides that codes for specific mRNA nucleotides e. a set of four mRNA nucleotides that codes for a specific amino acid

b. a set of three mRNA nucleotides that codes for a specific amino acid

Cloning a gene after isolating it requires which actions? Select all that apply. a. expression of the protein in mammalian cells b. identification of the transformants that have the gene of interest c. ligation into a vector d. transformation of the recipient cells with the vector with the gene of interest e. use of a virus to amplify the cloned gene DNA

b. identification of the transformants that have the gene of interest c. ligation into a vector d. transformation of the recipient cells with the vector with the gene of interest

In general, what causes normal cells to become cancer cells? a. cell cycle arrest b. loss of cell cycle control c. loss of the ability to divide d. apoptosis

b. loss of cell cycle control

Mutant versions of genes that are normally involved in driving the cell cycle are known as a.malignant genes.. b. oncogenes c. tumor suppressors. d. attenuators. e. Proto‑oncogenes.

b. oncogenes

The way that proteins fold into beta pleated sheets and alpha helices is dependent on their a. tertiary structure. b. primary structure. c. secondary structure. d. peptide bonds. e. quaternary structure.

b. primary structure.

Most bacterial RNA polymerases are made up of five subunits that have distinct functions for transcription. Which of the subunits does not permanently associate with the enzyme core? a. beta (β) b. sigma (σ) c. omega (ω) d. beta prime (β′) e. alpha (α)

b. sigma (σ)

Which of these is not involved in the initiation of translation in bacteria? a. GTP and initiation factors b. tRNA carrying the next amino acid that will occupy the A site c. small and large ribosomal subunits d. tRNA carrying N-formylmethionine that will occupy the P site e. mRNA

b. tRNA carrying the next amino acid that will occupy the A site

A key discovery leading to the structure of DNA was done by Chargaff. He found that ____. Select all that apply. a. the amount of A equals the amount of C, and the amount of G equals the amount of T b. the amount of A equals the amount of T, and the amount of G equals the amount of C c. the tetranucleotide hypothesis was false d.the amount of A equals the amount of G, and the amount of C equals the amount of T

b. the amount of A equals the amount of T, and the amount of G equals the amount of C c. the tetranucleotide hypothesis was false

The number of hydrogen bonds between complementary G−C pairs is a. one. b. three. c. zero. d. two. e. four.

b. three.

Some people with turner syndrome are 45, X/46, XY mosaics. How could this mosaicism arise? a. A cell gains an X chromosome soon after fertilization in an XY embryo b. A cell gains a Y chromosome soon after fertilization in an XX embryo c. A cell loses a Y Chromosome soon after fertilization of XY embryo d. A cell loses an X chromosome soon after fertilization in XY embryo e. A cell loses a Y chromosome soon after fertilization in an XX embryo

c. A cell loses a Y Chromosome soon after fertilization of XY embryo

Plasmids are small circular DNA molecules found in bacteria that replicate separately from chromosomes. Why are plasmids essential for recombinant DNA technology? a. Plasmids can cleave the sugar-phosphate bonds in DNA molecules in a staggered manner, creating single‑stranded, "sticky" ends of DNA where the gene of interest can attach. b. Plasmids are able to rapidly reproduce exact copies of cells, so they provide a means to acquire a large number of cells that contain a particular gene of interest. c. DNA from a gene of interest can be inserted into a plasmid, then the modified plasmid can be inserted into a bacterial cell to replicate a gene of interest many times. d. Plasmids provide the enzymatic action required to denature a molecule of DNA from a gene of interest that can be used in recombinant DNA technology.

c. DNA from a gene of interest can be inserted into a plasmid, then the modified plasmid can be inserted into a bacterial cell to replicate a gene of interest many times.

Which component required for prokaryotic DNA replication is not involved in "unwinding" the DNA template? a. initiator proteins b. single‑strand binding proteins c. DNA ligase d. DNA helicase e. DNA gyrase

c. DNA ligase

How do the nucleus and ribosomes work together to generate a protein? a. Ribosomes migrate into the nucleus, attach to a gene in the DNA, and use the gene as a transcript to synthesize a specific protein. b. Ribosomes produce mRNA that migrates into the nucleus and uses a gene in the DNA as instructions to synthesize a specific protein. c. In the nucleus, DNA is transcribed to mRNA, which the ribosomes use as instructions to synthesize a specific protein. d. A specific gene breaks away from the DNA and exits the nucleus, allowing the ribosomes to use the gene as instructions to synthesize a protein.

c. In the nucleus, DNA is transcribed to mRNA, which the ribosomes use as instructions to synthesize a specific protein.

Which statement describes the semiconservative model of DNA replication correctly? a. It proposes that the entire double‑stranded DNA molecule serves as a template for a whole new molecule of DNA. b. It proposes that both nucleotide strands break down into fragments, which then serve as templates for the synthesis of new DNA molecules. c. It proposes that the two nucleotide strands unwind and each serves as a template for a new DNA molecule.

c. It proposes that the two nucleotide strands unwind and each serves as a template for a new DNA molecule.

Which is not a characteristic of the 5' cap? a. The 5' cap increases the stability of the mRNA molecule. b. The 5' cap facilitates the binding of the ribosome to the mRNA. c. The 5' cap is a tag for mRNA degradation. d. The 5' cap is added to the mRNA by a 5'-5' phosphodiester bond. e. The 5' cap influences the removal of introns.

c. The 5' cap is a tag for mRNA degradation.

What contribution did James Watson and Francis Crick make to our understanding of DNA? a. They produced a clear X‑ray diffraction picture of the three‑dimensional structure of DNA. b. They found that proteins are not used as the genetic code, but that DNA is the genetic code. c. They pieced together the available evidence and modeled the structure of DNA. d. They discovered that there are equal amounts of cytosine and guanine in the DNA.

c. They pieced together the available evidence and modeled the structure of DNA.

A structure formed by a single‑stranded DNA or RNA molecule that has complementary sequences is a. a methylated strand. b. a helix. c. a hairpin. d. a triple strand.

c. a hairpin.

A strong covalent bond between adjacent nucleotides is a. a van der Waals bond. b. an ionic bond. c. a phosphodiester bond. d. a phosphate bond. e. a hydrogen bond.

c. a phosphodiester bond.

The major contribution of Franklin and Wilkins to the study of DNA was a. use of specific enzymes to destroy one molecule. b. use of a blender to separate virus coats off cells. c. an X‑ray diffraction pattern. d. a ball‑and‑stick model. e. creation of bacteriophages specific for studying DNA.

c. an X‑ray diffraction pattern.

which of the statements about the genetic code are most accurate? a. three initiation codons set the three possible reading frames b. the genetic code is generally overlapping c. an initiation codon sets the reading frame d. the promoter sets the reading frame e. the genetic code is generally-non-overlapping

c. an initiation codon sets the reading frame e. the genetic code is generally-non-overlapping

What is the role of the acceptor arm of the tRNA molecule? a. binding to the codon sequence of the mRNA b. binding to the codon sequence in the DNA c. binding a specific amino acid d. binding to the growing polypeptide chain e. binding to the ribosome

c. binding a specific amino acid

What is the key feature of DNA that allows it to be copied? a. Okazaki fragments b. the arrangement of chromosomes c. complementary base pairing d. the sugar-phosphate backbone

c. complementary base pairing

Traditional analysis of mutants (natural or induced) to determine gene function is known as a. reverse genetics. b. molecular genetics. c. forward genetics. d. functional genetics. e. transmission genetics.

c. forward genetics.

select the viruses that can cause human cancer? a. poliovirus b. human immunodeficiency virus (HIV) c. hepatitis B d. human papillomavirus e. Epstein-Barr virus

c. hepatitis B d. human papillomavirus e. Epstein-Barr virus

Which description applies to alternative mRNA splicing? a. heritable changes in gene expression that occur without altering the DNA sequence b. protein modifications such as addition of a functional group or structural changes such as folding c. processing of exons in mRNA that results in a single gene coding for multiple proteins d. a gene cluster controlled by a single promoter that transcribes to a single mRNA strand e. mRNA modifications such as additions of a 5′‑cap and 3′ poly‑A tail and removal of introns

c. processing of exons in mRNA that results in a single gene coding for multiple proteins

What is necessary for the addition of the poly(A) tail? a. at least one intron at the end of the pre‑mRNA b. the Shine-Dalgarno sequence c. the consensus sequence, AAUAAA d. mRNA degradation enzymes e. mRNA chaperone proteins

c. the consensus sequence, AAUAAA

Which is the most precise definition of a gene? a. all sequences of DNA that code for a single mRNA molecule b. all DNA sequences that code for a particular inherited trait c. the entire DNA sequence that is required to transcribe and encode a single RNA molecule d. all sequences of DNA that code for an RNA molecule e. the sequence of nucleotides that codes for amino acids in a protein

c. the entire DNA sequence that is required to transcribe and encode

What is the role of the eukaryotic promoter in transcription? a. the complex that unwinds DNA for transcription b. the region removed during transcript splicing c. the site where transcription factors bind and function d. the origin of replication e. the site where transcription stops

c. the site where transcription factors bind and function

Which item contains the TATA‑binding protein (TBP)? a. bacterial RNA polymerase b. Rut enzyme c. transcription factor TFIID d. Rho complex e. sigma subunit

c. transcription factor TFIID

In Avery, MacLeod, and McCarty's experiments, homogenates from heat‑killed bacteria were treated with different enzymes, and then the ability of those homogenates to transform bacteria was assayed. Under which condition would transformation not occur? a. treatment with RNase b. treatment with protease c. treatment with DNase d. treatment with RNase and protease

c. treatment with DNase

Are all eukaryotic genes colinear? a.Yes, because all genes produce protein products. b. Yes, because all codons in a eukaryotic gene are translated into a protein. c.No, because some eukaryotic genes have introns that are not translated. d. Yes, because the order of the codons and amino acids is the same in eukaryotes. e. No, because there are often several genes that code for the same protein.

c.No, because some eukaryotic genes have introns that are not translated.

Which statement about chromosomes inversions is correct? a. Chromosome inversion lead to increase in crossovers b. Chromosome inversions flip a segment of a chromosome 180 degrees c. Chromosome inversions can reduce the number of chromosomes in a cell d. Chromosome inversions do not affect gene expression

chromosome inversions flip a segment of a chromosome 180 degrees

What happens during the initiation step of DNA transcription? a. The mRNA detaches from the RNA polymerase as the RNA polymerase leaves the DNA strand. b. RNA polymerase moves along the template strand of the DNA creating an mRNA strand. c. A ribosome attaches to the initiation codon of a completed mRNA strand. d. A portion of the DNA unwinds and RNA polymerase attaches to the DNA within the transcription bubble.

d. A portion of the DNA unwinds and RNA polymerase attaches to the DNA within the transcription bubble.

Which one of the statements accurately describes gel electrophoresis? a. It requires the use of DNA probes. b. Larger DNA fragments move more quickly than smaller fragments. c. Fragments can be visualized by use of infrared light. d. DNA moves through the gel toward the positive electrode. e. Cellulose is used for the gel material.

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

Which description about prokaryotic versus eukaryotic DNA replication is not correct? a. In both prokaryotes and eukaryotes, the new and old DNA strands are assembled in an antiparallel manner. b.In prokaryotes, there is only one origin of replication; in eukaryotes, there are many. c. In prokaryotes, there is only a single replication bubble; in eukaryotes, there are many. d. In prokaryotes, the DNA replication is unidirectional; in eukaryotes, the replication is bidirectional. e. In both prokaryotes and eukaryotes, the DNA undergoes negative supercoiling during replication.

d. In prokaryotes, the DNA replication is unidirectional; in eukaryotes, the replication is bidirectional.

Which statement best describes Alfred Knudson's "two‑hit hypothesis?" a. Retinoblastoma results from the phosphorylation of two promoter sites, both of which are necessary for cancer to develop. b. Retinoblastoma results from mutations in two different loci that interact with one another, both of which are necessary for cancer to develop. c. Retinoblastoma results from an oncogene and a mutant tumor-suppressor gene, both of which are necessary for cancer to develop. d. Retinoblastoma results from two separate genetic defects, both of which are necessary for cancer to develop. e. Retinoblastoma results when an individual inherits a mutant gene from both parents, both of which are necessary for cancer to develop.

d. Retinoblastoma results from two separate genetic defects, both of which are necessary for cancer to develop.

Suppose Nicole recently learned that she inherited a mutant RB1 allele from her mother, who had retinoblastoma. RB1 is a tumor suppressor gene that is related to retinoblastoma. Why would Nicole be at higher risk for getting retinoblastoma at an earlier age than her sister, Tiffany, who inherited a normal RB1 allele from their mother? a. If an individual has even one mutation in a tumor suppressor gene, cancer will not be suppressed. b. An individual who inherited two functional alleles of a tumor suppressor gene is less likely to eat highly carcinogenic foods. c. One mutant allele of a tumor suppressor gene increases the likelihood that the wild-type allele will also mutate. d. Someone with one mutant allele in a tumor suppressor gene only requires a mutation in the one remaining normal allele for tumors to form.

d. Someone with one mutant allele in a tumor suppressor gene only requires a mutation in the one remaining normal allele for tumors to form.

What happens during the termination step of DNA transcription? a. A ribosome attaches to the initiation codon of a completed mRNA strand b. A portion of the DNA unwinds and RNA polymerase attaches to the DNA within the transcription bubble c. RNA polymerase moves along the template strand of the DNA creating an mRNA strand d. The mRNA detaches from the RNA polymerase as the RNA polymerase leaves the DNA strand

d. The mRNA detaches from the RNA polymerase as the RNA polymerase leaves the DNA strand

Aneuploidy is an umbrella term referring to multiple kinds of conditions in which an individual has an abnormal number of chromosomes or their species. Some patients on the abnormal tab of karyotype virtual interactive suffer from different types of aneuploidy. Use the interactive to determine which form of aneuploidy patient 251 suffers from. a. Triploidy b. Monosomy c. Inversion d. Trisomy

d. Trisomy

How is the transcription start site determined in bacteria? a. by the presence of an enhancer element b. by the presence of a DNA bubble c. by the presence of the TATA box d. by the binding of RNA polymerase to the consensus sequences of the promoter e. by the binding of the first primer

d. by the binding of RNA polymerase to the consensus sequences of the promoter

Restriction endonucleases a. are used in standard DNA sequencing reactions. b. are used to cut RNA at defined sequences. c. were identified as a protozoan defense mechanism against viruses. d. can be used to create pieces of DNA with cohesive ends. e. have no specific sequence requirements for recognition or cutting.

d. can be used to create pieces of DNA with cohesive ends.

Alternative splicing produces a. mRNAs of different lengths from the same amino acid sequences b. genes of different lengths from the same DNA c. pre‑mRNAs of different lengths from the same DNA d. mRNAs of different lengths from the same pre‑mRNA e. pre‑mRNAs of different lengths from the same mRNA

d. mRNAs of different lengths from the same pre‑mRNA

A powerful genetic engineering technique used for the amplification of sequences of DNA is a. reverse transcription chain amplification (RTCA). b. restriction fragment length polymorphism (RFLP) analysis. c. chromatin immunoprecipitation (ChIP). d. polymerase chain reaction (PCR). e. ligation‑based amplification (LBA).

d. polymerase chain reaction (PCR).

Which enzyme is responsible for the replication of chromosome ends in germ cells and certain proliferating somatic cells? a. DNA ligase b. DNA polymerase δ c. topoisomerase d. telomerase e. Geminin

d. telomerase

What did Griffith discover with his experiments? a. that the genetic material contains acidic and phosphate groups b. that bacteria can infect mice c. that DNA is the genetic material d. the transforming principle in bacteria e. that protein is the genetic material

d. the transforming principle in bacteria

Which of these is the first step of translation elongation? a. The small and large ribosomal subunits combine with mRNA and the tRNA carrying methionine. b. The ribosome translocates down the mRNA in the 5' -> 3' direction. c. The mRNA attaches to the small ribosomal subunit. d. A peptide bond is formed between the amino acids attached to the tRNAs in the P and A sites. e. A charged tRNA binds to the A site.

e. A charged tRNA binds to the A site.

Which is not true regarding cancer cells? a. Most, if not all, cancer cells arise from defects within the DNA. b. Cancer cells rob healthy tissues of nutrients. c. Cancer cells divide rapidly and continuously. d. Cancer cells can travel to distant sites within the body and set up new tumors. e. Cancer cells respond to normal cell cycle controls but proliferate at an abnormal rate.

e. Cancer cells respond to normal cell cycle controls but proliferate at an abnormal rate.

How does cancer differ from most other genetic disorders? a. Cancer is always caused by one or more mutations in genes expressed in only one organ system. Most other genetic disorders are the result of mutations that affect all cell types. b. Mutations in proteins involved in signal transduction pathways cause cancer but do not result in other genetic disorders. c. Most genetic disorders involve genes that rarely mutate. Most cancers are the result of mutations in rapidly mutating genes, which explains why cancer is so common. d. All cancers are the result of epigenetic changes, whereas most other genetic disorders are the result of changes in the DNA sequence. e. Most genetic disorders are inherited through germ cells from parents. Most cancers are, to some extent, the result of mutations in somatic cells that occur during an organism's lifetime.

e. Most genetic disorders are inherited through germ cells from parents. Most cancers are, to some extent, the result of mutations in somatic cells that occur during an organism's lifetime.

Which of the events occur during eukaryotic translation initiation? a. The ribosome reaches the end of the mRNA and dissociates, releasing the polypeptide chain. b. A tRNA binds a codon and the ribosome adds amino acids from each tRNA to the polypeptide chain. c. A protein recognizes the stop codon and the ribosome dissociates from the mRNA. d. Codons in the mRNA are recognized by rRNAs, and tRNAs add the amino acid to the polypeptide chain. e. The small ribosomal subunit binds with a specific tRNA to the mRNA and scans for a start codon.

e. The small ribosomal subunit binds with a specific tRNA to the mRNA and scans for a start codon.

What is the function of the spliceosome? a. The spliceosome protects the 5' end of mRNA by adding a 7-methylguanosine cap. b. The spliceosome removes the Shine-Delgarno sequence from the 5' end of the mRNA. c. The spliceosome transcribes ribosomal RNA and transfer RNA genes. d. The spliceosome adds a stretch of about 170 adenine nucleotides to the 3' end of the mRNA. e. The spliceosome produces a mature mRNA by connecting two exons and releasing the intron.

e. The spliceosome produces a mature mRNA by connecting two exons and releasing the intron.

Which statement best describes the clonal evolution of tumors? a. Tumor cells gain the ability to travel to other sites in the body, where they establish secondary tumors. b. Environmental factors can contribute to a cell becoming cancerous, and these factors may interact with genetic predispositions to cancer. c. Both oncogenes and tumor‑suppressor genes contribute to cancer but differ in their modes of action and dominance. d. If one or more of the required mutations is inherited, fewer additional mutations are required to produce cancer, and the cancer will tend to run in families. e. Tumor cells acquire more somatic mutations that allow them to become increasingly more aggressive in their proliferative properties.

e. Tumor cells acquire more somatic mutations that allow them to become increasingly more aggressive in their proliferative properties.

The sugar in DNA is called "deoxyribose" because it a. is missing a 3'-OH group. b. binds the nitrogen base via an O atom. c. is missing a 5'−OH group. d. contains a 2'− OH group. e. is missing a 2'−OH group.

e. is missing a 2'−OH group.

Which statement represents the definition of a reversion (reverse mutation)? a. RNA interference b. two‑hybrid test c. site‑directed mutagenesis d. mutation from wild‑type allele to mutant allele e. mutation from mutant allele to wild‑type allele

e. mutation from mutant allele to wild‑type allele

When mRNAs are being translated simultaneously by multiple ribosomes, the structure is known as a(n) a. polytene. b. copolymer. c. operon. d. polycistron. e. polyribosome.

e. polyribosome.

The spread of a complete metaphase chromosome set presented for diagnostic purposes is called a ____ a. Karyotype b. Translocation c. Polyploidy d. Genome

karyotype

Which statement about aneuploidy is true? a. Aneuploidy is a change in number of chromosome sets b. One form of aneuploidy is a loss of both members of homologous pair of chromosome c. The rarest aneuploidies in humans are those of sex chromosomes d. Most autosomal aneuploidies develop normally and have a normal life span

one form of aneuploidy is a loss of both members of homologous pair of chromosome

Additional copies of a gene _____ cause cellular problems. a. Always b. Never c. Sometimes

sometimes

Which statement about chromosome translocation is correct? a. Translocation and "crossing over" refer to the same phenomenon b. Translocations do not affect chromosome number c. Translocation can affect gene expression by moving a gene under the control of a different promoter d. Translocations only take place within a chromosome

translocation can affect gene expression by moving a gene under the control of a different promoter

Which statement about down syndrome is true? a. The probability of a child having down syndrome does not correlate with maternal age b. Trisomy of chromosome 21 is well tolerated enough to give rise to fully-developed individuals c. The primary cause for down syndrome is the robertsonian translocation d. Down syndrome never runs in the family, as it based on a random aneuploidy event

trisomy of chromosome 21 is well tolerated enough to give rise to fully-developed individuals

True or false: ALl chromosomes of the same species would have the same centromeric positions. a. True b. False

true