Which of the following statements best describes the process carried out by glutamine synthetase?

This activity contains 44 questions.

	Who formulated the one gene–one enzyme hypothesis? ()   Watson and Crick Beadle and Tatum Hershey and Chase Franklin None of the listed responses is correct.

	Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of __________. ()   proteins lipids RNA carbohydrates DNA

	Which of the following statements is true? ()   Each DNA base codes for three amino acids. Each gene codes for three proteins. It takes three genes to code for one protein. Each triplet has many different meanings. 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. ()   U ... T T ... G U ... A A ... U T ... A

	Generally speaking, how many genetic codes are there? ()   20 one four one for each organism three

	What mRNA codon would be made from the DNA triplet 3′-CGT-5′? ()   5′-ATU-3′ 5′-GCA-3′ 3′-TCU-5′ 5′-CTA-3′ 3′-GCA-5′

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

	The codons AAA, CCC, GGG, and UUU specify the amino acids lysine, proline, glycine, and phenylalanine, respectively. If the base sequence 5′-CCCAAATTTGGG-3′ is present in the coding strand of a stretch of DNA, what polypeptide sequence would be encoded by the corresponding template strand? ()   lys-pro-gly-phe pro-lys-phe-gly gly-phe-lys-pro phe-gly-pro-lys gly-phe-pro-lys

	How many nucleotides are needed to code for a protein with 450 amino acids? ()   at least 150 at least 300 at least 450 at least 900 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 __________. ()   inaccurate incomplete not specific redundant tricky

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

	In a eukaryotic cell, transcription takes place __________. ()   on the cell membrane in the rough endoplasmic reticulum in the cytoplasm on free ribosomes in the nucleus

	Which of the following best describes the arrangement of genetic information in a DNA molecule? ()   A gene is composed of overlapping, three-nucleotide words on a template strand of DNA. The three-nucleotide words of a gene are serially arranged on both strands of DNA at a specific locus. The three-nucleotide words of a gene are arranged in a nonoverlapping series on the DNA template strand. Information in a gene is made up of two-, three-, or four-nucleotide words, depending on the amino acids specified. A gene is made up of a linear, nonoverlapping series of the amino acids in a polypeptide.

	Which of the following catalyzes the linkage between ribonucleotides to form RNA during gene expression? ()   RNA polymerase aminoacyl-tRNA synthetase a ribozyme tyrosinase tRNA

	One strand of a DNA molecule has the following sequence: 3′-AGTACAAACTATCCACCGTC-5′. In order for that strand to be transcribed, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated. ()   centromere intron exon AUG codon promoter

	During the transcription of a given portion of a DNA molecule __________. ()   mRNA is synthesized on both chains of the DNA molecule at once mRNA is synthesized on both chains of the DNA molecule, but first on one side and then the other mRNA is synthesized on only one of the chains 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 All of the listed responses are correct.

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

	Which of the following statements is FALSE?()   In bacteria, proteins called transcription factors enhance the affinity of RNA polymerase to the promoter sites of genes. In bacteria, transcription of a gene is initiated when the RNA polymerase by itself recognizes and binds to the promoter of the gene. 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. In eukaryotes, transcription factors generally bind to a specific DNA region containing the sequence TATA before RNA polymerase can bind to the promoter. All of the listed responses are correct.

	In eukaryotes, which of the following mechanisms operates after transcription, but before translation of mRNA into protein? ()   RNA splicing DNA packaging into nucleosomes action of repressors and activators construction of a transcription initiation complex All of the listed responses are correct.

	Which of the following accurately describes the usual process of transcription for eukaryotic genes? ()   Exons are not transcribed. Introns are not transcribed. Both introns and exons are transcribed, but the RNA transcribed from introns does not leave the nucleus. Both introns and exons are transcribed, but neither type of transcribed region leaves the nucleus. Exons and introns are transcribed, and the RNA transcribed from both types of transcribed region leaves the nucleus.

	Which of the following statements correctly describes mRNA processing? ()   Introns are cut out of the primary transcript, and the resulting exons are spliced together. Exons are cut out of the primary transcript, and the introns are spliced together. Introns are cut out of the primary transcript and spliced together at the end of the transcript. Exons are cut out of the primary transcript and transported to the endoplasmic reticulum. 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? ()   Different systems of DNA unpacking could result in two different mRNAs. A point mutation might have altered the gene. Exons from the same gene could be spliced in different ways to make different mRNAs. Different transcription factors were involved in the transcription of the two mRNAs. The two proteins have different functions in the cell.

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

	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 __________. ()   in a double-stranded DNA molecule during translation during transcription when an mRNA codon paired with a tRNA anticodon It is impossible to say, given this information.

	The function of tRNA during protein synthesis is to __________. ()   deliver amino acids to their proper site during protein synthesis guide ribosomal subunits out of the nucleus through nuclear pores attach mRNA to the small subunit of the ribosome process mRNA transcribe mRNA

	Which of the following summaries of protein synthesis is correct? ()   Replicated DNA leaves the nucleus, is transported to a ribosome, and catalyzes the polymerization of amino acids in a protein. DNA exchanges its thymine units with uracil in polymerase. This activates polymerase, and it starts joining amino acids together. Transfer RNAs line up on a ribosome, and amino acids bind to them with hydrogen bonds. Messenger RNA is made on a DNA template, and then amino-acid-bearing transfer RNAs bind to the mRNA through codon-anticodon pairing. 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 __________. ()   peptide linkages hydrophobic interactions covalent bonds ionic bonds hydrogen bonds

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

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

	The first amino acid inserted into a new polypeptide chain in eukaryotic cells is usually __________. ()   glycine serine methionine adenosine monophosphate alanine

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

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

	Polysomes may be defined as __________. ()   microfilaments and microtubules groups of lysosomes degrading the same protein groups of ribosomes translating the same mRNA groups of chromosomes 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 __________. ()   there are two types of ribosomes: one group that synthesizes cytoplasmic proteins only, and another type that synthesizes secreted or compartment-specific proteins only 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 proteins destined for secretion or for a specific compartment are all synthesized in the nucleus, whereas cytoplasmic proteins are all synthesized in the cytoplasm each compartment in the cell (the nucleus, lysosome, and so forth) has its own set of ribosomes that synthesize proteins unique to that compartment ribosomes contain two types of subunits

	Consider the following list of events in the expression of a eukaryotic gene. What is their proper sequence? () 1. translation 2. RNA processing 3. transcription 4. modification of protein   1, 2, 3, 4 3, 2, 1, 4 4, 2, 3, 1 2, 3, 4, 1 1, 2, 4, 3

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

	Which of the following statements regarding the structure and function of tRNA is FALSE? ()   Each type of tRNA molecule translates a particular mRNA codon into a particular amino acid. 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. 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. Although there are 61 codons that code for amino acids, there are only 45 different tRNA molecules. 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 __________. ()   the deletion of one nucleotide a missense mutation the insertion of one nucleotide a nonsense mutation a silent or neutral mutation

	Which of the following types of mutation is LEAST likely to affect the function of the protein corresponding to the gene in which the mutation occurs? ()   addition of single bases base-pair substitution insertion of three bases deletion of single bases nonsense mutation

	A base-pair substitution mutation in a germ cell line is likely to have NO effect on phenotype if the substitution __________. ()   forms a new stop codon occurs in an intron changes a stop codon to a codon specifying an amino acid changes the structure of an enzyme 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 __________. ()   manufactured proteins to be short and defective the DNA to break up into thousands of short segments incorrect pairing between mRNA codons and amino acids no bad effects, as long as the stop codons are not also inserted into tRNA 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) __________. ()   nonsense mutation frame-shift mutation inversion mutation silent mutation missense mutation

	Ultraviolet (UV) radiation is damaging to cells because it __________. ()   pokes holes in the nuclear envelope blocks all translation causes mutations in the DNA deactivates the enzymes needed for DNA replication leads to disassembly of the cytoskeleton

	When genes are expressed, they produce __________. ()   enzymes RNA molecules phenotypic traits polypeptides The second and fourth responses are correct.

Which of the following best describes the effect of enzyme action?

Which of the following best explains why pancreatic amylase is able to break down starches but not lipids?

Which of the following is true regarding enzymes?