ch 17 Flashcards
Which of the following mechanisms is most likely to cause a phenotypic change?
D) A single nucleotide deletion in an exon coding for an active site.
Which molecule or reaction supplies the energy or polymerization of nucleotides in the process of transcription?
B) The phosphate bonds in the nucleotide triphosphates that serve as substrates.
You want to engineer a eukaryotic gene into a bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?
C) A bacterial promoter sequence.
In eukaryotic cells, transcription cannot begin until ______
B) Several transcription factors have bound to the promoter.
In E. coli, if RNA polymerase is missing _______, then transcription initiation would not occur at the appropriate intitiation sites.
c) sigma
Scientists studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters (the -10 box and the -35 box). These two regions of the promoter ______
B) bind the sigma subunit that is associated with RNA polymerase.
Eukaryotes have three RNA nuclear polymerases. The primary function of RNA polymerase II is transcription of _______
D) protein-coding genes
What is responsible for termination of transcription in eukaryotic protein-coding genes?
A) a polyadenylation, or poly(A), signal
A ribozyme is ______
B) an RNA with catalytic activity.
(picture)
As shown in the figure above, the mRNA transcript is smaller than the length of the DNA that codes for it because ______
B) post-transcriptional modification removes the introns.
As scientists were unraveling the mysteries associated with transcription and translation in eukaryotes, they covered there was not a one-to-one correspondence between the nucleotide sequence of a gene and the base sequence of the mRNA it codes for. They propose the gene-in-pieces hypothesis. How could the genes-in-pieces hypothesis be explained?
A) Introns are noncoding segments of DNA that are present in the initial transcript, but are removed by splicing.
What molecules in the spliceosome catalyze the intron removal reactions?
B) ribozymes
Codons are three–base sequences that specify the addition of a single amino acid. How do you eukaryotic codons and prokaryotic codons compare?
D) Codons are a nearly universal language among all organisms.
Which of the following occurs in prokaryotes but not in eukaryotes?
B) Concurrent (or coupled) transcription and translation.
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________.
E) binding of the anticodon to the codon and the attachment of amino acids to tRNAs.
What ensures that the correct amino acid is added during translation?
A) the anticodon of a properly formed aminoacyl tRNA
(picture)
In the figure aboce, what is the function of the AGU on the lower loop of the tRNA?
b) it base pairs with a codon on the mRNA.
(picture)
In the same figure, what is the function of the ACC sequence at the 3’ end?
A) it attaches to an amino acid.
What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure above?
C) hydrogen bonding between pairs.
The anticodon of a particular tRNA molecule is ______
A) complimentary to the corresponding mRNA codon.
Translation directly involves ______
mRNA, tRNA, ribosomes, and GTP.
During elongation, which site in the ribosome represents the location where a codon is being read?
C) A site
Once a peptide bond has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next?
A) Translocation
How does the termination of translation take place?
B) A stop codon is reached.
