Ch. 14 Practice Test

Who formulated the one gene-one enzyme hypothesis? a) Watson and Crick b) Beadle and Tatum c) Hershey and Chase Franklin d) None of the listed responses is correct.

Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of _____. a) proteins b) lipids c) RNA d) carbohydrates e) DNA

Which of the following statements is true? a) Each DNA base codes for three amino acids. b) Each gene codes for three proteins. c) It takes three genes to code for one protein. d) Each triplet has many different meanings. e) Each amino acid in a protein is coded for by three bases in the DNA.

When RNA is being made, the RNA base _____ always pairs with the base _____ in DNA. a) U ... T b) T ... G c) U ... A d) A ... U e) T ... A

Generally speaking, how many genetic codes are there? a) 20 b) one c) four d) one for each organism e) three

What mRNA codon would be made from the DNA triplet CGT? a) ATU b) GCA c) TCU d) CTA e) UCG

The number of nucleotide bases "read" together on the mRNA to designate each amino acid is _____; this unit is called a(n) _____. a) two ... dipeptide b) three ... triose c) two ... anticodon d) three ... codon e) one ... amino acid

The codons AAA, CCC, GGG, and UUU specify the amino acids lysine, proline, glycine, and phenylalanine, respectively. What peptide sequence would be encoded by the sequence 5'-CCCAAATTTGGG-3', if present in the coding strand of the DNA? a) lys-pro-gly-phe b) pro-lys-phe-gly c) gly-phe-lys-pro d phe-gly-pro-lys e) gly-phe-pro-lys

How many nucleotides are needed to code for a protein with 450 amino acids? a) at least 150 b) at least 300 c) at least 450 d) at least 900 e) at least 1,350

In many cases, more than one codon codes for the same amino acid. Because of this, we say that the code is _____. a) inaccurate b) incomplete c) not specific d) redundant e) tricky

Bacteria can transcribe and translate human genes to produce functional human proteins because _____. a) the genetic code is nearly universal b) bacterial ribosomes and eukaryotic ribosomes are identical c) eukaryotes do not really need a nucleus d)RNA has catalytic properties e) bacterial and eukaryotic RNA polymerases are identical

In a eukaryotic cell, transcription takes place _____. a) on the cell membrane b) in the rough endoplasmic reticulum c) in the cytoplasm d) on free ribosomes e) in the nucleus

Which of the following best describes the arrangement of genetic information in a DNA molecule? a) A gene is composed of overlapping, three-nucleotide words on a template strand of DNA. b) The three-nucleotide words of a gene are serially arranged on both strands of DNA at a specific locus. c) The three-nucleotide words of a gene are arranged in a nonoverlapping series on the DNA template strand. d) By overlapping the three-nucleotide words of a gene, the amount of information a DNA molecule can hold is maximized. e) By analyzing the linear order of amino acids in a polypeptide, the exact order of the three-nucleotide words of a gene arranged on the template strand of DNA can be determined.

At one point, as a cell carried out its day-to-day activities, the nucleotides GAT were paired with the nucleotides CUA. This pairing occurred _____. a) in a double-stranded DNA molecule b) during translation c) during transcription d) when an mRNA codon paired with a tRNA anticodon e) It is impossible to say, given this information.

Which of the following catalyzes the linkage between ribonucleotides to form RNA during gene expression? a) RNA polymerase b) RNA ligase c) a ribozyme d) reverse transcriptase e) tRNA

One strand of a DNA molecule has the following sequence: 3'-AGTACAAACTATCCACCGTC-5'. In order for transcription to occur in that strand, there would have to be a specific recognition sequence, called a(n) _____, to the left of the DNA sequence indicated. a) centromere b) intron c) exon d) AUG codon e) promoter

During the transcription of a given portion of a DNA molecule _____. a)mRNA is synthesized on both chains of the DNA molecule at once b) mRNA is synthesized on both chains of the DNA molecule, but first on one side and then the other c) mRNA is synthesized on only one of the chains d) half of the mRNA is synthesized on half of one chain; then the other half of the mRNA is made on the other half of the DNA e) Any of the listed patterns may be found.

In transcription, _____. a) the promoter region acts as an initial binding site for RNA polymerase b) only one of the DNA strands is used as the template c) the RNA nucleotides used are produced by the cell d) All of the listed responses are correct. e) None of the listed responses is correct.

Which of the following statements is false? a) In bacteria, proteins called transcription factors enhance the affinity of RNA polymerase to the promoter sites of genes. b) In bacteria, transcription of a gene is initiated when the RNA polymerase by itself recognizes and binds to the promoter of the gene. c) The initiation of gene transcription in eukaryotes requires the binding of proteins called transcription factors to the TATA box in the promoter region of a gene. d) A relaxation of chromatin packing in eukaryotic cells can facilitate the binding of transcription factors to a promoter of a gene. e) All of the listed responses are correct.

In eukaryotes, which of the following mechanisms of gene regulation operates after transcription, but before translation of mRNA into protein? a) RNA splicing b) DNA packaging into nucleosomes c) action of repressors and activators d) protein degradation e) All of the listed responses are correct.

Which of the following accurately describes the usual process of transcription for eukaryotic genes? a) Exons are not transcribed. b) Introns are not transcribed. c) Exons are transcribed, but the RNA transcribed from introns does not leave the nucleus. d) Both introns and exons are transcribed, but the RNA transcribed from them does not leave the nucleus. e) Exons and introns are transcribed, and the RNA transcribed from them leaves the nucleus.

Which of the following statements correctly describes mRNA processing? a) Introns are cut out of the primary transcript, and the resulting exons are spliced together. b) Exons are cut out of the primary transcript, and the introns are spliced together. c) Introns are cut out of the primary transcript and spliced together at the end of the transcript. d) Exons are cut out of the primary transcript and transported to the endoplasmic reticulum. e) Introns are cut out of the primary transcript and transported to the ribosomes.

A cell biologist found that two different proteins with largely different structures were translated from two different mRNAs. These mRNAs, however, were transcribed from the same template within the cell nucleus. Which mechanism below could best account for this? a) Different systems of DNA unpacking could result in two different mRNAs. b) A point mutation might have altered the gene. c) Exons from the same gene could be spliced in different ways to make different mRNAs. d) Different transcription factors were involved in the transcription of the two mRNAs. e) The two proteins have different functions in the cell.

The function of tRNA during protein synthesis is to _____. a) deliver amino acids to their proper site during protein synthesis b) guide ribosome subunits out of the nucleus through nuclear pores c) attach mRNA to the small subunit of the ribosome d) process mRNA e) transcribe mRNA

Which of the following summaries of protein synthesis is correct? a) DNA transposons leave the nucleus, are transported to a ribosome, and catalyze the polymerization of amino acids in a protein. b) DNA exchanges its thymine units with uracil in polymerase. This activates polymerase, and it starts joining amino acids together. c) Transfer RNAs line up on a ribosome, and amino acids bind to them with hydrogen bonds. d) Messenger RNA is made on a DNA template, and then amino-acid-bearing transfer RNAs bind to it through codon-anticodon pairing. e) DNA strands separate in the nucleus to form mRNA. mRNA leaves the nucleus and is transcribed into tRNA on ribosomes.

The bonds that hold tRNA molecules in the correct three-dimensional shape are _____. a) peptide linkages b) hydrophobic interactions c) covalent bonds d) ionic bonds e) hydrogen bonds

During translation in a eukaryotic cell _____. a) ribosomes move into the nucleus b) tRNA carries amino acid molecules to the nucleus, where they are added to a growing polypeptide chain c) polypeptides are synthesized at ribosomes, according to instructions carried by mRNA d) mRNA is synthesized by the bonding of free nucleotides to the bases on the template strand of DNA e) ribosomes move out of the nucleus

The P site of a ribosome does which of the following? a) It holds the tRNA that is carrying the next amino acid to be added to the growing polypeptide chain. b) It holds the tRNA carrying the growing polypeptide chain. c) It helps "unzip" DNA during transcription. d) It catalyzes the addition of amino acids to the tRNAs. e) It recognizes the promoter during transcription initiation.

The first amino acid inserted into a new polypeptide chain in eukaryotic cells is usually _____. a) glycine b) serine c) methionine d) adenosine monophosphate e) alanine

Which of the following is a post-translational modification of a polypeptide? a) cleavage of a polypeptide into two or more chains b) removal of introns and splicing of exons c) formation of a polysome that allows simultaneous formation of many polypeptides from one mRNA transcript d) The growing polypeptide signals the ribosome to attach to the ER. e) complementary base pairing of mRNA and tRNA in the ribosome

During translation, amino acid chain elongation occurs until _____. a) no further amino acids are needed by the cell b) all tRNAs are empty c) the polypeptide is long enough d) the ribosome encounters a "stop" codon e) the ribosome runs off the end of the mRNA strand

Polysomes may be defined as _____. a) microfilaments and microtubules b) groups of lysosomes c) groups of ribosomes d) groups of chromosomes e) groups of peroxisomes

Cells are able to distinguish proteins destined for secretion or for segregation to specific intracellular compartments from those that will remain in the cytoplasm because _____. a) there are two types of ribosomes: one group that synthesizes cytoplasmic proteins only, and another type that synthesizes secreted or compartment-specific proteins only b) some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER c) proteins destined for secretion or for a specific compartment are all synthesized in the nucleus, whereas cytoplasmic proteins are all synthesized in the cytoplasm d) each compartment in the cell (the nucleus, lysosome, and so forth) has its own set of ribosomes that synthesize proteins unique to that compartment e) ribosomes contain two types of subunits

What is the proper order of the following events in the expression of a eukaryotic gene? 1. translation 2. RNA processing 3. transcription 4. modification of protein a) 1, 2, 3, 4 b) 3, 2, 1, 4 c) 4, 2, 3, 1 d) 2, 3, 4, 1 e) 1, 2, 4, 3

The mRNA codons 5'-CAA-3' or 5'-CAG-3' are translated as the amino acid glutamine by _____. a) the tRNA with an anticodon 5'-GUU-3' and glutamine at its other end b) by tRNA molecules that have been charged with glutamine by two different aminoacyl-tRNA synthetases c) separate tRNA molecules with anticodons 3'-GUU-5' and 3'-GUC-5', respectively d) the same tRNA with the anticodon 3'-GUU-5' e) the small and large ribosomal units

Which of the following statements regarding the structure and function of tRNA is false? a) Each type of tRNA molecule translates a particular mRNA codon into a particular amino acid. b) Although each tRNA consists of a relatively short, single RNA strand, this single strand can achieve a three-dimensional structure by folding back upon itself and forming covalent bonds between complementary bases. c) The nucleotide sequence at both the amino acid attachment and the anticodon ends of each tRNA is instrumental in specifying which amino acid is attached to the tRNA by aminoacyl-tRNA synthetase. d) Although there are 61 codons that code for amino acids, there are only 45 different tRNA molecules. e) The second and third listed responses are false.

A geneticist found that a particular mutation had no effect on the polypeptide encoded by the gene. This mutation probably involved _____. a) the deletion of one nucleotide b) a missense mutation c) the insertion of one nucleotide d) a nonsense mutation e) a silent or neutral mutation

A base-pair substitution mutation in a germ cell line is likely to have no effect on phenotype if the substitution _____. a) forms a new stop codon b) occurs in an intron c) changes a stop codon to a codon specifying an amino acid d) changes the structure of an enzyme e) prevents the initiation of transcription of the DNA sequence that codes for ATP synthase

A virus infects a cell and randomly inserts many short segments of DNA containing a stop codon throughout an organism's chromosomes. This will probably cause _____. a) manufactured proteins to be short and defective b) the DNA to break up into thousands of short segments c) incorrect pairing between mRNA codons and amino acids d) no bad effects, as long as the stop codons are not also inserted into tRNA e) All of the listed responses are correct

A point mutation in which a single base pair is inserted or deleted from DNA is called a(n) _____. a) nonsense mutation b) frame-shift mutation c) inversion mutation d) translocation mutation e) missense mutation

Ultraviolet (UV) radiation is damaging to cells because it _____. a) pokes holes in the nuclear envelope b) blocks all translation c) causes mutations in the DNA d) deactivates the enzymes needed for DNA replication e) shreds the cytoskeleton and leads to free radicals

Transcription factors are found in _____. () a) archaea b) bacteria and eukaryotes c) bacteria and archaea d) eukaryotes e) archaea and eukaryotes

On the off chance that you might contract an archaeal infection, how might it be treated? () a) It could be treated with antiviral medications because archaea are similar to viruses. b) It could be treated with antibiotics such as streptomycin that inactivate bacterial ribosomes because archaea and bacteria have similar ribosomes. c) It could be treated with drugs that disrupt gene splicing because archaea remove introns in the nucleus before sending mRNA to ribosomes. d) It could be treated with a vaccine. e) None of the listed responses is correct.

When genes are expressed, they produce _____. () a) enzymes b) RNA molecules c) phenotypic traits d) polypeptides e) The second and fourth responses are correct.

What is a key difference in gene expression between eukaryotic and prokaryotic cells? () a) In prokaryotes, proteins are assembled directly from DNA. b) RNA polymerases are involved only in initiation in eukaryotes. c) In prokaryotic cells, the mRNA transcript is immediately available as mRNA without processing. d) In eukaryotic cells, transcribed RNA sequences function as termination signals. e) Prokaryotes do not contain ribosomes.