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20 Cards in this Set

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When the function of the newly made polypeptide is to be secreted from the cell where it has been made, what must occur?
A) It must be translated by a ribosome that remains free of attachment to the ER.
B) Its signal sequence must target it to the ER, from which it goes to the Golgi.
C) It has a signal sequence that must be cleaved off before it can enter the ER.
D) It has a signal sequence that targets it to the cell's plasma membrane where it causes exocytosis.
E) Its signal sequence causes it to be encased in a vesicle as soon as it is translated.
Its signal sequence must target it to the ER, from which it goes to the Golgi.
Suppose that a mutation alters the formation of a tRNA such that it still attaches to the same amino acid (phe) but its anticodon loop has the sequence AAU that binds to the mRNA codon UUA (that usually specifies leucine leu).
A) The modified tRNA will cause this mRNA to make only nonfunctioning product.
B) The tRNA-leu will not be able to enter the site of the ribosome to bind to the UUA.
C) One mutated tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones.
D) The tRNA will be so unstable that it will not participate in translation.
E) The mutated tRNA will result in an amino acid variant in all copies of the protein.
One mutated tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones.
Why might a point mutation in DNA make a difference in the level of protein's activity?
A) It might result in a chromosomal translocation.
B) It might exchange one stop codon for another stop codon.
C) It might exchange one serine codon for a different serine codon.
D) It might substitute an amino acid in the active site.
E) It might substitute the N-terminus of the polypeptide for the C-terminus.
It might substitute an amino acid in the active site.
In the 1920s Muller discovered that X-rays caused mutation in Drosophila. In a related series of experiments in the 1940s, Charlotte Auerbach discovered that chemicals–she used nitrogen mustards–have a similar effect. A new chemical food additive is developed by a cereal manufacturer. Why do we test for its ability to induce mutation?
A) We worry that it might cause mutation in cereal grain plants.
B) We want to make sure that it does not emit radiation.
C) We want to be sure that it increases the rate of mutation sufficiently.
D) We want to prevent any increase in mutation frequency.
E) We worry about its ability to cause infection.
We want to prevent any increase in mutation frequency.
Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?
A) a deletion of a codon
B) a deletion of two nucleotides
C) a substitution of the third nucleotide in an ACC codon
D) a substitution of the first nucleotide of a GGG codon
E) an insertion of a codon
a deletion of two nucleotides
What is the effect of a nonsense mutation in a gene?
A) It changes an amino acid in the encoded protein.
B) It has no effect on the amino acid sequence of the encoded protein.
C) It introduces a premature stop codon into the mRNA.
D) It alters the reading frame of the mRNA.
E) It prevents introns from being excised.
introduces a premature stop codon into the mRNA
A frameshift mutation could result from
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.
either an insertion or deletion of a base.
Which of the following DNA mutations is the most likely to be damaging to the protein it specifies?
A) a base-pair deletion
B) a codon substitution
C) a substitution in the last base of a codon
D) a codon deletion
E) a point mutation
base pair substitution
Which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein?
A) a base substitution
B) a base deletion near the start of a gene
C) a base deletion near the end of the coding sequence, but not in the terminator codon
D) deletion of three bases near the start of the coding sequence, but not in the initiator codon
E) a base insertion near the end of the coding sequence, but not in the terminator codon
a base deletion near the start of a gene
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
A) a base-pair substitution.
B) a nucleotide mismatch.
C) a frameshift mutation.
D) a polypeptide missing an amino acid.
E) a nonsense mutation.
a polypeptide missing an amino acid.
Which of the following mutations is most likely to cause a phenotypic change?
A) a duplication of all or most introns
B) a large inversion whose ends are each in intergenic regions
C) a nucleotide substitution in an exon coding for a transmembrane domain
D) a single nucleotide deletion in an exon coding for an active site
E) a frameshift mutation one codon away from the 3' end of the nontemplate strand
a single nucleotide delation in an exon coding for an active site.
If a protein is coded for by a single gene and this protein has six clearly defined domains, which number of exons below is the gene likely to have?
A) 1
B) 5
C) 8
D) 12
E) 14
8
) Which of the following statements is true about protein synthesis in prokaryotes?
A) Extensive RNA processing is required before prokaryotic transcripts can be translated.
B) Translation can begin while transcription is still in progress.
C) Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles.
D) Translation requires antibiotic activity.
E) Unlike eukaryotes, prokaryotes require no initiation or elongation factors.
Translation can begin while transcription is still in progress.
Of the following, which is the most current description of a gene?
A) a unit of heredity that causes formation of a phenotypic characteristic
B) a DNA subunit that codes for a single complete protein
C) a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
D) a DNA—RNA sequence combination that results in an enzymatic product
E) a discrete unit of hereditary information that consists of a sequence of amino acids
a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
Gene expression in the domain Archaea in part resembles that of bacteria and in part that of the domain Eukarya. In which way is it most like the domain Eukarya?
A) Domain Archaea have numerous transcription factors.
B) Initiation of translation is like that of domain Eukarya.
C) There is only one RNA polymerase.
D) Transcription termination often involves attenuation.
E) Post-transcriptional splicing is like that of Eukarya.
Domain Archaea have numerous transcription factors
Which of the following is true of transcription in domain Archaea?
A) It is regulated in the same way as in domain Bacteria.
B) There is only one kind of RNA polymerase.
C) It is roughly simultaneous with translation.
D) Promoters are identical to those in domain Eukarya.
E) It terminates in a manner similar to bacteria.
It is roughly simultaneous with translation
In comparing DNA replication with RNA transcription in the same cell, which of the following is true only of replication?
A) It uses RNA polymerase.
B) It makes a new molecule from its 5' end to its 3' end.
C) The process is extremely fast once it is initiated.
D) The process occurs in the nucleus of a eukaryotic cell.
E) The entire template molecule is represented in the product.
The entire template molecule is represented in the product.
In order for a eukaryotic gene to be engineered into a bacterial colony to be expressed, what must be included in addition to the coding exons of the gene?
A) the introns
B) eukaryotic polymerases
C) a bacterial promoter sequence
D) eukaryotic ribosomal subunits
E) eukaryotic tRNAs
a bacterial promoter sequence
When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply?
A) There are 20,000 genes.
B) Each gene codes for one protein.
C) Any other regions are "junk" DNA.
D) There are also genes for RNAs other than mRNA.
E) The species is highly evolved.
There are also genes for RNAs other than mRNA
According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?
A) 0
B) 1
C) 2
D) 3
E) It cannot be determined from the pathway.
2