BIOL200 Simutext questions
if each base in an mRNA sequence were translated into one amino acid in a polypeptide, for how many types of amino acids could mRNA code?
4; there are 4 bases in mRNA, if each translates to one amino acid, there would be four possible choices of amino acids
The DNA below represents a short sequence in the middle of a gene. What will the RNA sequence be when this stretch of DNA is transcribed? 5′-ATGGC-3′ coding strand 3′-TACCG-5′ template strand
5'-AUGGC-3'
What RNA sequence is complementary to the DNA sequence: 5′-AGC-3′?
5'-GCU-3'
what is not apart of RNA processing? RNA synthesis adding a 5' cap adding a 3' tail intron removal
RNA synthesis
when does the polypeptide begin folding?
during translation
where is the 5' end
furthest away from RNA polymerase
what must RNA have in order to be translated?
indication of where to start translation indication of polypeptides amino acid sequence indication of where to stop translation
when a tRNA leaves the ribosome, how is it different than when it entered?
it no longer carries an amino acid
where are codons located?
mRNA
how are amino acids matched to bases in the mRNA sequences?
molecules of tRNA are used to match each triplet of bases in the mRNA to an amino acid
where along the gene does RNA polymerase begin transcription?
near the promoter
can the 3' tail be added early during transcription?
no
is tRNA apart of mRNA?
no
is the stop codon part of the open reading frame?
no
is the transcription start site apart of the promoter?
no
Suppose you successfully transplant an entire gene from a eukaryotic cell into a prokaryotic cell. Can you be sure that the prokaryotic mRNA will be the same as the mRNA produced by the eukaryotic cell (ignoring the 5′ cap and 3′ tail)?
no, because the gene could include introns, which would not be removed in the prokaryote
the promoter region of a gene is never translated into a protein, is the promoter an intron?
no, because the promoter is not transcribed.
During alternative splicing, do you think the remaining exons can be freely arranged? For instance, in the example above would you ever see mRNA with exon 3, then exon 1, then exon 2, arranged 5′-to-3′?
no, the relative order of exons is preserved
if each unique doublet of two bases in the mRNA sequence were translated into one type of amino acid, would there be a sufficient number of unique two base sequences to represent all 20 amino acids ?
no, this would lead 4^2=16, which is not 20.
what happens to the DNA during transcription?
one strand of DNA is copied into RNA
what is eukaryotic RNA transcript called before the cap and tail are added?
pre- mRNA
why don't prokaryotes transport mRNA out of the nucleus
prokaryotes don't have a nucleus
what is true about promoters? all promoter sequences for an organism are identical promoters are the first part of the gene to be transcribed promoters indicate where RNA polymerase attaches the DNA promoters can be found at the 5' end of DNA strand
promoters indicate where RNA polymerase attaches the DNA
what proteins are encoded by genes?
proteins that maintain cell membranes proteins that help convert sugar to energy protein channels that allow molecules in and out of cells
A single DNA molecule can contain thousands of genes, and each of these has its own terminator. How are terminators helpful for the overall process of gene expression?
without terminators, a huge amount of DNA would be transcribed at once, resulting in a giant RNA transcript with too much information
can the same pieces of DNA and RNA be used for transcription and translation multiple times?
yes
during elongation, at which tRNA binding site on the ribosome do tRNAs enter?
A
the peptide bond is formed between amino acids attached to tRNAs at which two sites?
A&P
translation starts at the ..., is performed by... and is signaled to end by ...
AUG start codon, ribosome, stop codon
what molecule contains promoters?
DNA
in what binding sites are the tRNAs never attached?
E
When cells make proteins, is the gene in the DNA destroyed or used up in the process?
No, the information in DNA is copied into a molecule of RNA
is RNA consumed (destroyed) as it is translated into a polypeptide?
No, the information in RNA is used, but the RNA molecule is not consumed
after the large subunit binds and the ribosome is fully assembled, which tRNA binding site does the first tRNA, which carries methionine, occupy?
P
which of the following statements about the RNA produced by transcription is true? RNA is double stranded RNA can base pair with DNA RNA and DNA use the same bases
RNA can base pair with DNA
which about polypeptides is true? polypeptides consist of one or more proteins a protein can be composed of a simple polypeptide amino acids are composed of poly peptides all proteins include multiple polypeptides
a protein can be composed of a simple polypeptide
what must be present in the hexokinase gene?
a region that codes for the hexokinase gene an area that indicates where to start transcription an area that indicates where to end transcription
How are DNA, RNA and polypeptides similar in structure?
all three are polymers built from smaller molecules
in what direction does transcription proceed relative to the promoter?
away from it (downstream)
which strand of DNA is used by RNA polymerase to make the RNA?
template strand
which consists of more nucleotides, the 5' cap or the 3' tail?
the 3' tail
what happens to the DNA after RNA polymerase finishes transcribing the gene?
the DNA strands come back together
how are the RNA transcript, template strand and coding strand related?
the RNA sequence is most similar to the coding strand of DNA because they are both complementary to the template strand
if the 5' cap or 3' tail is omitted, what is the effect?
the RNA transcript cannot exit the nucleus and is eventually destroyed
what is difference between the promoter and the ribosome binding site?
the promoter is on DNA, the ribosome binding site is on mRNA
what happens when you skip intron removal and translate the resulting protein?
the protein is different
if introns were not removed from eukaryotic pre-mRNA, how would this effect the amino acid sequence of the protein?
the proteins amino acid sequence would be altered due to translation of introns
how does the ribosome move along the mRNA after incorporating an amino acid?
the ribosome moves 3 bases along the mRNA
what is true of translation termination?
the stop codon binds with a release factor, which is a protein
during translation initiation, what happens after the small ribosomal subunit binds?
the tRNA carrying methionine binds to the mRNA
what accounts for the effect observed when intron removal is skipped?
the translated introns result in a different amino acid sequence
suppose that after transcription, a cell mistakenly adds 30 random nucleotides to the 3' end of an mRNA molecule. what effect would this have on the polypeptide after translation?
there would be no effect. ( after stop codon )
how large are exons relative to introns?
they can be larger or smaller than introns
what is the function of a gene?
to contain information for building specific cellular products
in which direction does the ribosome move along the mRNA?
toward the 3' end
how is transcription affected by the absence of a promoter?
transcription cannot occur
how is transcription affected by the absence of a terminator
transcription continues past the end of a gene
transcription starts at the ...; performed by... and is signaled to end by ...
transcription start site, RNA polymerase, terminator