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CH 15

Terms in this set (63)

DNA affects the traits of an organism by providing the instructions for synthesizing _______.
A) proteins
B) nucleotides
C) codons
D) amino acids
A
Gene expression involves two phases, ________ and translation.
A) replication
B) transcription
C) initiation
D) condensation
B
Messenger RNA molecules contain information that is used to synthesize ________.
A) nucleotides
B) amino acids
C) polypeptides
D) fatty acids
C
To begin transcription, RNA polymerase must bind to a segment of DNA called the ________.
A) initiation site
B) primer
C) inducer
D) promoter
E) transcription bubble
D
The strand of DNA that is not transcribed is called the ________ strand.
A) coding
B) noncoding
C) template
D) complementary
A
During ________, a ribosome assembles a polypeptide whose amino acid sequence is specified by the nucleotide sequence in a molecule of mRNA.
A) transcription
B) translation
C) replication
D) posttranscriptional modification
B
The sequence of nucleotides in a DNA molecule is called the ________ code.
A) protein
B) ribosomal
C) translation
D) genetic
E) amino acid
D
Crick and his colleagues proposed that the genetic code consists of a series of blocks of information, called ________, each corresponding to one amino acid in an encoded protein.
A) alleles
B) codons
C) genes
D) polypeptides
B
Gene ________ refers to the combined processes of transcription and translation.
A) expression
B) replication
C) modification
D) regulation
A
During transcription of mRNA in eukaryotes, some sequences are cut out of the primary transcript and the remaining sequences are joined together. This processing of mRNA is called ________.
A) termination
B) translation
C) splicing
D) capping
E) elongation
C
The connection that exists between genes and hereditary traits is based on using the information encoded in genes to synthesize
A) codons.
B) nucleotides.
C) proteins.
D) histones.
E) complementary bases.
C
Both DNA and RNA are made up of building blocks known as
A) nucleotides.
B) nucleic acids.
C) amino acids.
D) genes.
E) codons.
A
The "one-gene/one-enzyme" hypothesis was proposed by
A) Watson and Crick.
B) Griffith.
C) Garrod.
D) Franklin.
E) Beadle and Tatum.
E
The polypeptide-making organelles, which consist of protein combined with RNA, are called
A) ribosomes.
B) Golgi bodies.
C) lysosomes.
D) centrosomes.
E) mitochondria.
A
During translation, amino acids are carried to the ribosome by
A) mRNA.
B) tRNA.
C) snRNA.
D) rRNA.
E) miRNA.
B
During ________, RNA polymerase synthesizes a molecule of RNA using DNA as a template.
A) mRNA splicing
B) translation
C) transcription
D) gene sequencing
E) termination
C
A codon is composed of how many bases?
A) one
B) two
C) three
D) four
E) 64
C
Ribosomes are complex aggregates of
A) RNA and DNA.
B) RNA and proteins.
C) RNA and sugars.
D) DNA and proteins.
E) nucleosomes and RNA.
B
The A, P, and E sites are progressively occupied by amino acids being assembled into a polypeptide. These sites are part of
A) DNA.
B) the large ribosomal subunit.
C) mRNA.
D) tRNA.
E) the spliceosome.
B
In eukaryotic cells, transcription occurs
A) on the surface of the nuclear membrane.
B) on ribosomes.
C) on spliceosomes.
D) inside the nucleus.
E) on the surface of the plasma membrane.
D
In prokaryotes, the form of RNA polymerase that can accurately initiate synthesis of RNA is called
A) the holoenzyme.
B) the core polymerase.
C) RNA polymerase II.
D) RNA polymerase III.
E) the sigma subunit.
A
During ________, nucleotide sequence information is changed into amino acid sequence information.
A) replication
B) sequencing
C) transcription
D) translocation
E) translation
E
The genetic code uses ________ nucleotide(s) to specify one amino acid.
A) one
B) two
C) three
D) four
E) 64
C
Which statement about the genetic code is false?
A) There is no punctuation or spacing between codons.
B) Nucleotides are always read in groups of three.
C) Every codon codes for one amino acid.
D) Some amino acids are specified by more than one codon.
E) The genetic code is almost universal, but not quite.
C
How many unique mRNA codons can be constructed from the four different RNA nucleotides?
A) four
B) 12
C) 16
D) 61
E) 64
E
During translation, the nucleotides that make up the mRNA are read in groups of three. These groups are called
A) codons.
B) anticodons.
C) exons.
D) introns.
E) templates.
A
The tRNA nucleotide sequence that pairs with bases on the mRNA is called a(n)
A) intron.
B) exon.
C) codon.
D) initiation factor.
E) anticodon.
E
Ribosome movement along the mRNA is called
A) transcription.
B) initiation.
C) replication.
D) translocation.
E) activation.
D
Specific amino acids are attached to tRNA molecules by
A) aminoacyl-tRNA synthetases.
B) hydrogen bonds.
C) anticodons.
D) deactivating enzymes.
E) initiation factors.
A
Codons that serve as "stop" signals for translation are recognized by
A) tRNA.
B) release factors.
C) anticodons.
D) translation terminators.
E) aminoacyl-tRNA synthetases
B
When a polypeptide is being assembled, the bond that forms between a newly added amino acid and the previous amino acid in the chain is a ________ bond.
A) hydrogen
B) hydrophobic
C) terminal
D) phosphodiester
E) peptide
E
During translation in prokaryotes, formation of the initiation complex requires all of the following except
A) a small ribosomal subunit.
B) mRNA.
C) tRNA charged with N-formylmethionine.
D) RNA polymerase.
E) initiation factors.
D
Eukaryotic mRNA molecules may contain noncoding sequences that must be removed before translation. These are called
A) anticodons.
B) introns.
C) exons.
D) nucleosomes.
E) noncodons.
B
The location of translation in prokaryotic cells is
A) in the nucleoid.
B) on ribosomes.
C) on the plasma membrane.
D) on mesosomes.
E) on chromosomes
B
In eukaryotes, pre-mRNA processing may involve all of the following except
A) removal of exons from the pre-mRNA.
B) addition of a 5' cap.
C) addition of a 3' poly-A tail
D) pre-mRNA splicing by the spliceosome.
A
The template strand of a DNA segment that codes for mRNA has the sequence: ATGCGT. Which tRNA anticodons would pair with the mRNA that is coded for by this sequence?
A) AUG CGU.
B) ATG CGT.
C) UAC GCA.
D) UAG CGU.
A
Although 61 different codons code for amino acids, cells contain fewer than 61 different tRNAs. Why?
A) Because the 5' base on the tRNA anticodon has some flexibility (wobble); thus, some tRNA anticodons can pair with more than one mRNA codon.
B) Although 61 different codons code for amino acids, any given cell contains fewer than 61.
C) Because the 5' base on the mRNA codon has some flexibility (wobble); thus, some mRNA codons can pair with more than one tRNA anticodon.
D) Because each amino acid is coded for by just one codon.
A
Eukaryotic and prokaryotic organisms differ in how they process genetic information. Which statements best explain one of these differences?
A) In prokaryotes, translation of the mRNA begins before transcription is complete. In eukaryotes, transcription and modification of the mRNA is completed before translation begins.
B) In prokaryotes, genes are transcribed directly into polypeptides. In eukaryotes, genes are transcribed into RNA which is used to assemble polypeptides.
C) In prokaryotes, translation occurs before genes are transcribed into mRNA. In eukaryotes, genes are transcribed into mRNA which is then translated into polypeptides.
D) In prokaryotes, introns are removed before genes are transcribed into mRNA. In eukaryotes, introns are removed after genes are transcribed into mRNA.
A
What is the first step during transcription initiation in prokaryotes?
A) the transcription bubble is formed
B) RNA polymerase binds to the promoter
C) the DNA double helix is unwound
D) RNA polymerase synthesizes a short primer
E) transcription factors bind to the TATA box sequence
B
Initiation of transcription differs from initiation of DNA replication in several ways. One difference is that initiation of transcription does not require
A) a promoter.
B) enzymes.
C) a primer.
D) a DNA template strand.
C
Transcription in prokaryotes is carried out by ________, which unwind(s) and transcribe(s) the gene.
A) RNA synthetase
B) RNA polymerase II
C) RNA polymerase III
D) transcription factors
E) RNA polymerase
E
Eukaryotes have ________ type(s) of RNA polymerase.
A) two
B) three
C) four
D) one
E) 64
B
In eukaryotes, each type of RNA polymerase recognizes a different
A) start codon
B) stop codon
C) promoter
D) release factor
E) transcription factor
C
Eukaryotic pre-mRNA molecules are modified
A) in the cytoplasm.
B) at the ribosome.
C) inside the nucleus.
D) as they pass through the nuclear membrane.
E) at the transcription bubble.
C
In eukaryotes, the 3' poly-A tail is attached to
A) poly-A polymerase.
B) mRNA.
C) tRNA.
D) the ribosome.
E) the template strand of DNA.
B
Why are there fewer tRNA anticodons than the 61 needed to match each mRNA codon that codes for an amino acid?
A) There is some flexibility in pairing between the 5' base of the codon and the 3' base of the anticodon.
B) There is some flexibility in pairing between the middle base of the codon and the middle base of the anticodon.
C) There is some flexibility in pairing between the 3' base of the codon and the 5' base of the anticodon.
D) There is some flexibility in pairing between all 3 bases of the codon and all 3 bases of the anticodon.
C
During translation, translocation refers to
A) releasing a tRNA molecule from the ribosome.
B) joining an amino acid to a tRNA molecule.
C) joining an amino acid to the next amino acid in the chain.
D) joining a tRNA molecule to the ribosome.
E) moving the ribosome along the mRNA molecule.
E
During protein synthesis in eukaryotes, what happens during RNA splicing?
A) The product of translation, called the primary transcript, is cut and some pieces are joined back together to form the mature mRNA.
B) The product of transcription, called the primary transcript, is cut and some pieces are joined back together to form the mature tRNA.
C) The product of transcription, called the secondary transcript, is cut and some pieces are joined back together to form the mature mRNA.
D) The product of transcription, called the primary transcript, is cut and some pieces are joined back together to form the mature mRNA.
E) The product of transcription, called the primary transcript, is cut and all pieces are joined back together to form the mature mRNA.
D
During protein synthesis in eukaryotes, which molecule passes from the nucleus to the cytoplasm and specifies the sequence of amino acids in the new polypeptide?
A) DNA
B) RNA polymerase
C) mRNA
D) rRNA
E) tRNA
C
Given the sentence "THE FAT CAT ATE THE RED RAT," which of the following would represent a frameshift mutation?
A) THE FAT RAT ATE THE RED CAT
B) THE CAT ATE THE RED RAT
C) THE FAC ATA TET HER EDR AT
D) THE FAT CAT ATE THE RED RAT
C
During the splicing reaction, the intron-exon junctions are recognized by
A) snRNPs.
B) miRNAs.
C) SRP RNAs.
D) the lariat.
E) the branch point.
A
In prokaryotes, the RNA polymerase holoenzyme consists of
A) the core polymerase plus two alpha subunits.
B) the core polymerase plus two beta subunits.
C) the core polymerase plus two alpha subunits, two beta subunits, and a sigma subunit.
D) the core polymerase plus a sigma subunit.
E) two alpha subunits, two beta subunits, and two sigma subunits.
D
Two 6-base sequences are present in bacterial promoters: TATAAT (located 10 nt upstream from the start site) and TTGACA (located 35 nt upstream from the start site). What is the significance of the fact that these two base sequences are different?
A) Binding sites for both the holoenzyme and ATP are provided.
B) Both the location of the start site and the direction of transcription can be established.
C) Binding sites for both the core polymerase and holoenzyme are provided.
D) The transcription bubble can be properly formed.
E) It allows RNA polymerase to distinguish between the template strand and the coding strand of the DNA molecule.
B
Within the transcription bubble, the 9 most recently added nucleotides in the newly synthesized RNA strand temporarily form a helix with the template DNA strand. How might transcription be affected if helix formation did not occur?
A) Rewinding the DNA molecule would be inhibited.
B) Unwinding the DNA molecule would be inhibited.
C) The position of the 5' end of the RNA would be unstable, inhibiting elongation.
D) The position of the 3' end of the RNA would be unstable, inhibiting elongation.
E) The position of the 5' end of the RNA would be unstable, stimulating elongation.
D
Cells conserve energy and resources by making active proteins only when they are needed. If a protein is not needed, which of the following methods of control would be the most energy-efficient?
A) block transcription
B) degrade the mRNA after it is made
C) prevent translation of the mRNA
D) degrade the protein after it is made
A
What is required for formation of the transcription initiation complex in eukaryotes?
A) binding of a transcription factor to the TATA box, followed by recruitment of additional transcription factors and recruitment of RNA polymerase II
B) binding of a transcription factor to the transcription bubble, followed by recruitment of additional transcription factors and recruitment of RNA polymerase III
C) binding of the sigma subunit to the start site followed by recruitment of RNA polymerase II
D) binding of RNA polymerase II to the TATA box, followed by recruitment of transcription factors
E) binding of the sigma subunit to promoter elements at -35 and -10, followed by recruitment of the core polymerase
A
What is the likely consequence of a mutation that alters the branch point within an intron?
A) no effect, since introns are not expressed
B) failure to form a lariat
C) failure of snRNPs to recognize the 5' end of intron
D) no exon shuffling
E) failure of snRNAs to combine with protein and form snRNPs
B
You are working to characterize a novel protein in mice. Analysis shows that high levels of the primary transcript that codes for this protein are found in tissue from the brain, muscle, liver, and pancreas. However, an antibody that recognizes the C-terminal portion of the protein indicates that the protein is present in brain, muscle, and liver, but not in the pancreas. What is the most likely explanation for this result?
A) The gene that codes for this protein is not transcribed in the pancreas.
B) The transcript is immediately degraded in the pancreas.
C) The transcript receives a 5' cap in the pancreas.
D) Alternative splicing in the pancreas creates a protein missing the domain that the antibody recognizes.
E) The transcript receives a 3' poly-A tail in the pancreas.
D
The mutation responsible for Huntington's disease is a
A) missense mutation.
B) nonsense mutation.
C) frameshift mutation.
D) triplet repeat expansion mutation.
D
How would a large chromosomal inversion affect the expression of a gene if the gene is located between the two break points but no breaks occur within the gene?
A) The inversion would probably have no effect on gene expression.
B) The gene would not be transcribed because it would be oriented in the wrong direction.
C) The gene would be transcribed in the 3' to 5' direction.
D) The gene would be transcribed normally but the mRNA would be translated in the 3' to 5' direction.
A
You are attempting to synthesize rRNA in a test tube using DNA isolated from mouse cells. In addition to the template DNA, ribonucleotides, and the necessary transcription factors, you should also add ________ to the test tube.
A) poly-A polymerase
B) RNA polymerase III
C) RNA polymerase II
D) RNA polymerase I
D
You are studying an individual with very low levels of insulin in her blood. Further analysis indicates that cells of her pancreas are producing normal levels of this protein, but it is accumulating in the cytoplasm rather than being secreted from the cells. Which hypothesis makes the most sense to explain this observation?
A) A small deletion has removed the nucleotides that code for the signal sequence at the amino terminus of the protein.
B) A missense mutation has caused premature termination during translation of this protein.
C) A chromosomal segment that includes the gene for insulin has been inverted.
D) A two-base deletion near the middle of the gene has altered the reading frame during translation of the protein.
E) A missense mutation has altered the ribosome-binding sequence at the 5' end of the mRNA.
A
A gene that codes for a protein was removed from a eukaryotic cell and inserted into a prokaryotic cell. Although the gene was successfully transcribed and translated, it produced a different protein than it produced in the eukaryotic cell. What is the most likely explanation?
A) There are slight differences in the genetic code for prokaryotes and eukaryotes.
B) Unlike eukaryotes, which have three different RNA polymerases, prokaryotes have a single RNA polymerase.
C) Eukaryotic genes often contain introns while prokaryotic genes do not.
D) Eukaryotic transcripts have a 5' cap while prokaryotic transcripts do not.
C
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