Ch 17 bio

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Alternative RNA splicing

can allow the production of proteins of different sizes from a single mRNA

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'

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

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

what is the function of GTP in translation

GTP energizes the formation of the initiation complex, using initiation factor

Which of the following is true of transcription in domain Archaea?

It is roughly simultaneous with translation.

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

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

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.

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

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

what is a ribozyme

an RNA with enzymatic activity

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

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

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

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 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

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

which of the following is a function of a signal peptide

to translocate polypeptides across the ER membrane

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 of the following provides some evidence that RNA probably evolved before DNA

DNA polymerase uses primer, usually made of RNA

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

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.

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

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

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 variations on translation would be most disadvantageous or a cell?

Translating polypeptides directly from DNA

Which of the following statements is true about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress.

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

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.

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

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 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

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


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