BIOL 1306 Chapter 13-17

A particular triplet of bases in the template strand of DNA is 5'-AGT-3'. The corresponding codon for the mRNA transcribed is A) 3'-UCA-5'. B) 3'-UGA-5'. C) 5'-TCA-3'. D) 3'-ACU-5'. E) either UCA or TCA, depending on wobble in the first base.

A) 3'-UCA-5'.

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? A) 8% B) 16% C) 31% D) 42%

A) 8%

Which of the following statements correctly describes one of the differences between embryonic and adult stem cells in animals? A) Embryonic stem cells can differentiate into more cell types than adult stem cells. B) Adult stem cells can differentiate into more cell types than embryonic stem cells. C) Embryonic stem cells have fewer genes than adult stem cells. D) Embryonic stem cells are localized to specific sites within the embryo, whereas adult stem cells are spread throughout the body.

A) Embryonic stem cells can differentiate into more cell types than adult stem cells.

Which of the following best describes the significance of the TATA box in eukaryotic promoters? A) It is the recognition site for a specific transcription factor. B) It sets the reading frame of the mRNA. C) It is the recognition site for ribosomal binding. D) It signals the end of the nucleotide sequence of the gene.

A) It is the recognition site for a specific transcription factor.

Which of the following best describes siRNA? A) a short double-stranded RNA, one of whose strands can block gene expression B) a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor C) a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits D) an RNA sequence that can block the expression of some transposons

A) a short double-stranded RNA, one of whose strands can block gene expression

The leading and the lagging strands of DNA formed during DNA replication differ in that A) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. B) the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. C) the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. D) the leading strand is synthesized at twice the rate of the lagging strand.

A) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

What is the function of topoisomerase? A) to unwind the DNA helix during replication B) to seal together the broken ends of DNA strands C) to add nucleotides to the 3' end of a growing DNA strand D) to degrade damaged DNA molecules E) to rejoin the two DNA strands (one new and one old) after replication

A) to unwind the DNA helix during replication

RNA polymerase moves in which direction along the DNA? A) 5' to 3' along whichever strand it's on B) 3' to 5' along the template strand C) 5' to 3' along the template strand D) 5' to 3' along the double-stranded DNA E) 3' to 5' along the nontemplate strand

B) 3' to 5' along the template strand

Which of the following statements is a likely explanation for why therapeutic cloning is considered acceptable by many? A) Use of adult stem cells is likely to produce more cell types than use of embryonic stem cells. B) Cloning to produce embryonic stem cells may lead to treatments for a large number of diseases. C) Cloning to produce stem cells relies on a different initial procedure than reproductive cloning. D) A clone that lives until the blastocyst stage does not yet have human DNA. E) No embryos would be destroyed in the process of therapeutic cloning.

B) Cloning to produce embryonic stem cells may lead to treatments for a large number of diseases.

What is the function of the release factor in translation? A) It separates tRNA in the A site from the growing polypeptide. B) It binds to the stop codon in the A site in place of a tRNA. C) It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. D) It releases the ribosome from the ER to allow polypeptides into the cytosol.

B) It binds to the stop codon in the A site in place of a tRNA.

Which of the following statements describes one difference between DNA replication in prokaryotes and DNA replication in eukaryotes? A) Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. B) Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. C) The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes. D) Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. E) Prokaryotes have telomeres, and eukaryotes do not.

B) Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

Which of the following statements best describes the termination of transcription in prokaryotes? A) RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase. B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript. C) RNA polymerase transcribes through an intron, which causes the polymerase to let go of the transcript. D) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome. E) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

What is meant by the description "antiparallel" regarding the two strands of nucleic acids that make up DNA? A) The twisting nature of DNA creates nonparallel strands. B) The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. C) Base pairings create unequal spacing between the two DNA strands. D) One strand contains only purines and the other contains only pyrimidines.

B) The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

Which enzyme was used to produce the molecule in Figure 13.3? A) ligase B) a restriction enzyme C) RNA polymerase D) DNA polymerase

B) a restriction enzyme

In eukaryotes, general transcription factors A) are required for the expression of specific protein-encoding genes. B) bind to other proteins or to a sequence element within the promoter called the TATA box. C) inhibit RNA polymerase binding to the promoter and begin transcribing. D) usually lead to a high level of transcription even without additional specific transcription factors. E) bind to sequences just after the start site of transcription.

B) bind to other proteins or to a sequence element within the promoter called the TATA box.

Which of the following processes can be effective in preventing the onset of viral infection in humans? A) taking vitamins B) getting vaccinated C) taking antibiotics D) applying antiseptics

B) getting vaccinated

Which of the following molecules, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator? A) ubiquitin B) inducer C) promoter D) repressor E) corepressor

B) inducer

Antiviral drugs that have become useful are usually associated with which of the following properties? A) ability to remove all viruses from the infected host B) interference with viral replication C) removal of viral proteinsD) removal of viral mRNAs

B) interference with viral replication

Which of the following responses correctly lists the order of events in a generalized viral replicative cycle? A) enzymes transcribe the viral genome into mRNA, the virus enters the cell, host enzymes replicate the viral genome B) the virus enters the cell, host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA C) host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA, the virus enters the cell D) the virus enters the cell, enzymes transcribe the viral genome into mRNA, host enzymes replicate the viral genome

B) the virus enters the cell, host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA

Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression? A) mRNA, tRNA, and rRNA are transcribed. B) RNA polymerase binds to the promoter. C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end. D) Transcription can begin as soon as translation has begun even a little. E) RNA polymerase requires a primer to elongate the molecule.

C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction? A) primase B) DNA ligase C) DNA polymerase III D) topoisomerase E) helicase

C) DNA polymerase III

Which of the following statements correctly describes chromatin? A) Heterochromatin is composed of DNA, whereas euchromatin is made of DNA and RNA. B) Both heterochromatin and euchromatin are found in the cytoplasm. C) Heterochromatin is highly condensed, whereas euchromatin is less compact. D) Euchromatin is not transcribed, whereas heterochromatin is transcribed.

C) Heterochromatin is highly condensed, whereas euchromatin is less compact.

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? A) It synthesizes RNA nucleotides to make a primer. B) It catalyzes the lengthening of telomeres. C) It joins Okazaki fragments together. D) It unwinds the parental double helix. E) It stabilizes the unwound parental DNA.

C) It joins Okazaki fragments together.

Which of the following statements correctly describes tumor-suppressor genes? A) They are frequently overexpressed in cancerous cells. B) They are cancer-causing genes introduced into cells by viruses. C) They can encode proteins that promote DNA repair or cell-cell adhesion. D) They often encode proteins that stimulate the cell cycle.

C) They can encode proteins that promote DNA repair or cell-cell adhesion.

Which of the following statements accurately describes one main characteristic of proto-oncogenes? A) Their normal function is to suppress tumor growth. B) They are produced by somatic mutations induced by carcinogenic substances. C) They code for proteins associated with normal cell growth. D) They are underexpressed in cancer cells.

C) They code for proteins associated with normal cell growth.

What is a ribozyme? A) an enzyme that uses RNA as a substrate B) an RNA with enzymatic activity C) an enzyme that catalyzes the association between the large and small ribosomal subunits D) an enzyme that synthesizes RNA as part of the transcription process E) an enzyme that synthesizes RNA primers during DNA replication

C) an enzyme that catalyzes the association between the large and small ribosomal subunits

hat is a ribozyme? A) an enzyme that uses RNA as a substrate B) an RNA with enzymatic activity C) an enzyme that catalyzes the association between the large and small ribosomal subunits D) an enzyme that synthesizes RNA as part of the transcription process E) an enzyme that synthesizes RNA primers during DNA replication

C) an enzyme that catalyzes the association between the large and small ribosomal subunits

A human pandemic is A) a viral disease that infects all humans. B) a flu that kills more than 1 million people. C) an epidemic that extends around the world. D) a virus that increases in mortality rate as it spreads.

C) an epidemic that extends around the world.

In a nucleosome, the DNA is wrapped around A) polymerase molecules. B) ribosomes. C) histones. D) a thymine dimer.

C) histones.

Which of the following modifications is most likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis? A) altering the nucleotide sequence of the DNA fragment without adding or removing nucleotides B) radioactively labeling the cytosine bases within the DNA fragment C) increasing the length of the DNA fragment D) leaving the length of the DNA fragment the same

C) increasing the length of the DNA fragment

Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript.i. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'Which components of the previous molecule will also be found in mRNA in the cytosol? B) 5' UTR I1 I2 I3 UTR 3' C) 5' E1 E2 E3 E4 3' D) 5' UTR E1 E2 E3 E4 UTR 3' E) 5' I1 I2 I3 3' F) 5' E1 I1 E2 I2 E3 I3 E4 3'

D) 5' UTR E1 E2 E3 E4 UTR 3'

Which of the following statements correctly describes one characteristic of the lytic cycle of viral replication? A) Many bacterial cells containing viral DNA are produced. B) Viral DNA is incorporated into the host genome. C) The viral genome replicates without destroying the host. D) A large number of phages are released at a time.

D) A large number of phages are released at a time.

Two potential functions that eukaryotic cells perform to regulate transcription are A) DNA methylation and histone amplification. B) DNA amplification and histone methylation. C) DNA acetylation and methylation. D) DNA methylation and histone modification. E) histone amplification and DNA acetylation.

D) DNA methylation and histone modification.

A new DNA strand elongates only in the 5' to 3' direction because A) DNA polymerase begins adding nucleotides at the 5' end of the template. B) Okazaki fragments prevent elongation in the 3' to 5' direction. C) replication must progress toward the replication fork. D) DNA polymerase can only add nucleotides to the free 3' end.

D) DNA polymerase can only add nucleotides to the free 3' end.

In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine. Which of the following investigators was (were) responsible for this discovery? A) Frederick Griffith B) Alfred Hershey and Martha Chase C) Oswald Avery D) Erwin Chargaff E) Matthew Meselson and Franklin Stahl

D) Erwin Chargaff

Which of the following is a function of a poly-A tail in mRNA? A) It adds the modified guanine to the 3' end of the mRNA. B) It indicates the site of translational termination. C) It is a sequence that codes for the binding of RNA polymerase to the DNA. D) It helps protect the mRNA from degradation by hydrolytic enzymes.

D) It helps protect the mRNA from degradation by hydrolytic enzymes.

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells? A) Proto-oncogenes first arose from viral infections. B) Proto-oncogenes are mutant versions of normal genes. C) Proto-oncogenes are genetic "junk." D) Proto-oncogenes normally help regulate cell division.

D) Proto-oncogenes normally help regulate cell division.

In animals, which of the following statements describes one difference between reproductive cloning and therapeutic cloning? A) Reproductive cloning uses totipotent cells, whereas therapeutic cloning does not. B) Reproductive cloning uses embryonic stem cells, whereas therapeutic cloning does not. C) Therapeutic cloning uses nuclei of adult cells transplanted into enucleated nonfertilized eggs, whereas reproductive cloning does not. D) Therapeutic cloning supplies cells that may treat disease, whereas reproductive cloning supplies cells that may be used to produce new individuals.

D) Therapeutic cloning supplies cells that may treat disease, whereas reproductive cloning supplies cells that may be used to produce new individuals.

Emerging viruses arise by A) mutation of existing viruses. B) the spread of existing viruses to new host species. C) the spread of existing viruses more widely within their host species. D) all of the above

D) all of the above

Accuracy in the translation of mRNA into the sequence of amino acids in a polypeptide depends on specificity in which of the following? A) binding of ribosomes to mRNA B) shape of the A and P sites of ribosomes C) attachment of amino acids to tRNAs D) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

D) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

Which of the following help(s) to separate the DNA strands apart while they are being replicated? A) primase B) ligase C) DNA polymerase D) helicase E) nuclease

D) helicase

Which of the following is a protein product of a regulatory gene? A) operon B) inducer C) promoter D) repressor E) corepressor

D) repressor

uppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome.If she moves the regulatory gene (lac I), along with its promoter, to a position some several thousand base pairs away from its normal position, which would you expect to occur? A) The repressor will no longer be made. B) The repressor will no longer bind to the operator. C) The repressor will no longer bind to the inducer. D) The lac operon will be expressed continuously. E) The lac operon will function normally.

E) The lac operon will function normally.

How is transformation in bacteria most accurately described? A) the creation of a strand of DNA from an RNA molecule B) the creation of a strand of RNA from a DNA molecule C) the infection of cells by a phage DNA molecule D) the type of semiconservative replication shown by DNA E) assimilation of external DNA into a cell

E) assimilation of external DNA into a cell

Which of the following types of mutations could result in a frameshift mutation? A) a base insertion only B) a base deletion only C) a base substitution only D) deletion of three consecutive bases E) either an insertion or a deletion of a base

E) either an insertion or a deletion of a base

In which order do the necessary enzymes act to repair a thymine dimer (repair od DNA) by nucleotide excision repair? A) nuclease, DNA polymerase, RNA primase B) helicase, DNA polymerase, DNA ligase C) DNA ligase, nuclease, helicase D) DNA polymerase, RNA polymerase, DNA ligase E) nuclease, DNA polymerase, DNA ligase

E) nuclease, DNA polymerase, DNA ligase

Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development? A) morphogenesis B) determination C) induction D) differentiation E) pattern formation

E) pattern formation

Which viruses have single-stranded RNA that acts as a template for DNA synthesis? A) lytic phages B) proviruses C) viroids D) bacteriophages E) retroviruses

E) retroviruses

A spliceosome attaches to pre-mRNA to add the poly A tails for processing.

False

Apoptosis involves specific process which includes lysis of the cell by other cells.

False

Pluripotent cells are undifferentiated cells used to construct plant prions.

False

An operon is a regulator that functions in activating the promoter region of a gen which leads to the activation of the polymerase enzyme.

True

Muscle cells differ from nerve cells mainly because they express different genes (determinants).

True

P53 is a gene which regulates the process of mRNA translation and prevents polypeptide formation.

True

RNA viruses require their own supply of certain enzymes because host cells lack enzymes that can replicate the viral genome

True

Reverse transcriptase is an enzyme that helps convert mRNA into DNA.

True

Transcription factors includes TATA box located near the promoter region of the pre-mRNA.

True

Bacteriophages are used to help bacteria infects various plants for genetic recombinations.

false