Ch 17 bio
Alternative RNA splicing
can allow the production of proteins of different sizes from a single mRNA
which of the following statements best describes the termination of transcription in prokaryotes
RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript
A particular triplet of bases in the coding sequence of DNA is AAA. the anticodon on the tRNA that binds the mRNA codon is
UUU
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 bacterial promoter sequence
which of the following DNA mutations is the most likely to be damaging to the protein it specifies
a base-pair deletion
what is a ribozyme
an RNA with enzymatic activity
which of the following is the first event to take place in translation in eukaryotes
the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
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
8
The nitrogenous base adenine is found in all members of which group?
ATP, RNA, and DNA
which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein
a base deletion near the start of a gene
Which of the following mutations is most likely to cause a phenotypic change
a single nucleotide deletion in an exon coding for an active site
Accuracy in the translation of mRNA into primary structure of a polypeptide depends on specificity in the
bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
what is the function of the release factor (RF)
it binds to the stop codon in the A site in place of a tRNA
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following
A gene from an organism can theoretically be expressed by any other organism
which of the following nucleotide triplets best represents a codon
A triplet in the same reading frame as an upstream AUG
54) Of the following, which is the most current description of a gene?
DNA sequence that is expressed to form a functional product: either RNA or polypeptide
The "universal" genetic code is now known to have exceptions. Evidence for this can be found if which of the following is true.
If UGA, usually a stop codon, is found to code for an amino acid such as tryptophan
Which of the following is true of transcription in domain Archaea?
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?
The entire template molecule is represented in the product.
Which of the following statements is true about protein synthesis in prokaryotes?
Translation can begin while transcription is still in progress.
in the structural organization of many eukaryotic genes, individual exons may be related to which of the following
the various domains of the polypeptide product
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
3' UCA 5'
A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate
Any mutation in the sequence is selected against
which of the following provides some evidence that RNA probably evolved before DNA
DNA polymerase uses primer, usually made of RNA
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
Domain Archaea have numerous transcription factors.
what is the function of GTP in translation
GTP energizes the formation of the initiation complex, using initiation factor
RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probable advantage for the organism of such sigma switching
It might allow the polymerase to recognize different promoters under certain environmental conditions
during splicing, which molecular component of the spliceosome catalyzes the excision reation
RNA
In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein
RNA polymerase II
Transcription in eukaryotes requires which of the following in addition to RNA polymerase
Several transcription factors (TFs)
When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply?
There are also genes for RNAs other than mRNA.
Which of the following variations on translation would be most disadvantageous or a cell?
Translating polypeptides directly from DNA
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 deletion of two nucleotides
which of the following does not occur in the prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression
a ply-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
a polypeptide missing an amino acid.
A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation?
an accumulation of A and no production of B and C
a frameshift mutation could result from
either an insertion or a deletion of a base
which of the following is a function of a poly-A signal sequence
it codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~10 35 nucleotides away.
what is the effect of a nonsense mutation in a gene
it introduces a premature stop codon into the mRNA
why might a point mutation in DNA make a difference in the level of proteins activity
it might substitute an amino acid in the active site
when the function of the newly made polypeptide is to be secreted from the cell where it has been made, what must occur
its signal sequence must target it to the ER, from which it goes to the Golgi
a transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is the best explained by the fact that
many noncoding stretches of nucleotides are present in mRNA
If A, B, and C are all required for growth, a strain mutant for the gene-encoding enzyme B would be capable of growing on which of the following media?
minimal medium supplemented with C only
If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme A would be able to grow on which of the following media?
minimal medium supplemented with nutrient B only
the process of translation, whether in prokaryotes or eukaryotes or eukaryotes, requires tRNAs amino acids, ribosomal subunits, and which of the following
polypeptide factors plus GTP
a mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. the consequence of this for the cell will be that
proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU
when translating secretory or membrane proteins, ribosomes are directed to the ER membrane by
signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane
an experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. which of the following hypotheses describes the most likely result
the amino acid methionine will not bind
in an experimental situation, a student researcher inserts an mRNA molecule into eukaryotic cell after he has removed its 5' cap and poly-A tail. which of the following would you expect him to find
the molecule is digested by restriction enzymes in the nucleus
The TATA sequence is found only several nucleotides away from the start site of transcription. This most probably relates to which of the following
the number of hydrogen bonds between A and T in DNA
there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. this is best explained by the fact that
the rules for base pairing between the third base of a codon and tRNA are flexible
which of the following is a function of a signal peptide
to translocate polypeptides across the ER membrane
