Mutations and Gene Expression (Final) Flashcards
Why is the cell type that a mutation occurs in relevant to inheritance?
a
Certain cell types (such as skin cells) have more mutations than others
b
Only certain cell types, the gametes, have DNA (and thus mutations) that is passed down to offspring
c
Cancers can only be passed down through skin cells, but not through other cell types such as neurons
d
What type of cell a mutation occurs in is not relevant to inheritance
b
Only certain cell types, the gametes, have DNA (and thus mutations) that is passed down to offspring
Which of the following would not result in increased mutation rates?
a
If all base pairs had the same shape
b
If a mutation causes loss-of-function of a mutator gene
c
If a mutation knocks out the ability to distinguish parental and daughter DNA strands
d
If a mutation knocked out the proofreading function of DNA polymerase
a
If all base pairs had the same shape
b
If a mutation causes loss-of-function of a mutator gene
c
If a mutation knocks out the ability to distinguish parental and daughter DNA strands
d
If a mutation knocked out the proofreading function of DNA polymerase
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon/triplet in the middle of the sequence. This most likely results in:
a
A substitution mutation
b
A protein missing an amino acid
c
A shift in the reading frame, such that all subsequent amino acids are affected
d
A much shorter amino acid sequence
e
A nucleotide mismatch
b
A protein missing an amino acid
Are mutations harmful?
a
No, because mutations in DNA result in better versions of genes
b
Yes, because mutated proteins can’t function
c
Yes, because DNA is damaged
d
It depends on whether/how a protein’s function is affected
d
It depends on whether/how a protein’s function is affected
Which of the following features is a significant difference in the function of DNA polymerases versus RNA polymerases?
a
RNA polymerase, but not DNA polymerase, is an enzyme that links a polymer of nucleotides.
b
DNA polymerase extends the growing chain in the 5’ to 3’ direction, whereas RNA polymerase extends growing chains from 3’ to 5’.
c
RNA polymerase produces a new strand that goes in the same direction as its template strand, whereas DNA polymerase can only produce anti-parallel strands
d
RNA polymerase does not require a primer to add new nucleotides.
e
None of the above are differences between RNA polymerase and DNA polymerase
d
RNA polymerase does not require a primer to add new nucleotides.
In a particular bacterial species, temperature-sensitive conditional mutations cause expression of one phenotype at one growth temperature and a different, mutated phenotype at another typically higher temperature. Imagine that when a bacterial cell carrying such a mutation is shifted from low to high growth temperatures, RNA polymerases in the process of elongation complete transcription normally, but no new transcripts can be started. Because the mutation seems to affect the initiation step of transcription, this mutation most likely affects:
a
the terminator sequence
b
the start codon
c
sigma
d
one of the polypeptides of the core RNA polymerase
c
sigma
there are many similarities and differences between DNA replication and transcription. Which of the following is false comparing the two processes?
a
They occur at different times. DNA replication occurs before cell division whereas transcription occurs during gene expression
b
They both produce nucleic acids and use enzymes called polymerases
c
Both processes occur in eukaryotes as well as in prokaryotes
d
Errors in DNA replication can affect the products of transcription
a
They occur at different times. DNA replication occurs before cell division whereas transcription occurs during gene expression
b
They both produce nucleic acids and use enzymes called polymerases
c
Both processes occur in eukaryotes as well as in prokaryotes
d
Errors in DNA replication can affect the products of transcription
In an experimental situation, a student researcher inserts an mRNA molecule into the cytoplasm of a eukaryotic cell after she has removed its 5’ cap and poly-A tail. Which of the following would you expect her to find?
a
The primary transcript would not be processed properly
b
The mRNA molecule would be digested by enzymes
c
tRNAs would become more resistant to degradation
d
Enzymes on the ribosome would add a cap and poly(A) tail
e
The mRNA would be quickly converted into a ribosomal subunit
b
The mRNA molecule would be digested by enzymes
You want to engineer a eukaryotic gene into bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?
a
eukaryotic polymerases
b
eukaryotic ribosomal subunits
c
a bacterial promoter sequence
d
eukaryotic tRNAs
e
the introns
c
a bacterial promoter sequence
In humans, skeletal muscles (e.g. the muscle you normally think of that allow you to move your fingers, arms, legs, etc) and smooth muscles (e.g. the muscles lining your blood vessels and digestive tract) produce two different versions of the same muscle protein, called alpha-tropomyosin. Researchers found that, though the two different versions of alpha-tropomyosin are different lengths of amino acids and have slightly different shape, they are produced using exactly the same DNA sequence in both skeletal and smooth muscle cells. Which of the following is the best explanation for this?
a
The X chromosome from your mother is always inactivated in your smooth muscle cells and the X chromosome from your father is always inactivated in your skeletal muscle cells
b
These different versions of the proteins are produced by alternative splicing of mRNA
c
These different versions of the protein are likely due to the effects of nondisjunction
d
This is variation produced by the effects of crossing over
e
None of the above would have this effect
b
These different versions of the proteins are produced by alternative splicing of mRNA
A mutant bacterial cell has a defective aminoacyl-tRNA 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:
a
the ribosome will skip a codon every time a UUU is encountered
b
the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons
c
proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU
c
proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU
All of the following are differences in transcription, RNA processing, and translation between prokaryotes and eukaryotes except:
a
the sigma factor associates with the promoter region in prokaryotes but in eukaryotes there are many transcription factors
b
the promoters in prokaryotes have a -35 and -10 box while in eukaryotes they are more variable
c
the mRNA goes through extensive modifications such as addition of a poly tail and a 5’ cap in eukaryotes but not in prokaryotes
d
in prokaryotes, during initiation, the tRNA carrying methionine enters the A site of the ribosome whereas in eukaryotes it enters the P site
e
All of the above are true
d
in prokaryotes, during initiation, the tRNA carrying methionine enters the A site of the ribosome whereas in eukaryotes it enters the P site
