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74 terms

Gen exam 3

Start/methionine codon
Stop Codons
Amino acid codons
Which of the following initially determines which DNA strand is the template strand, and therefore in which direction RNA polymerase II moves along the DNA?
the specific sequence of bases along the DNA strands
Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?
-A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
-Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes
-A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.
Amino acids are attached to tRNA by enzymes called _____________
aminoacyl-tRNA synthetase
The process, performed by the ribosome, of reading mRNA and synthesizing a protein is called _________
The RNA that has amino acid attached to it, and that binds to the codon on the mRNA, is called a _________
_________ of translation always happens at the start codon of the mRNA
_________ of translation happens when the ribosome hits a stop codon on the mRNA
A(n) _______ is a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway
The __________ is/are arranged sequentially after the promoter
genes of an operon
A(n) ______ is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place
A(n) _________ codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes
regulatory gene
Regulatory proteins bind to the ______ to control expression of the operon
A(n) _______ is a protein that inhibits gene transcription. In prokaryotes, this protein binds to the DNA in or near the promoter
A(n) ________ is a specific small molecule that binds to a bacterial regulatory protein and changed its shape so that it cannot bind to an operator, thus switching an operon on.
The role of the primers in PCR is ___________
to define the target redion and provide a 3' end that can be extended by taq polymerase
If there are five molecules of DNA containing the target region at the beginning of a PCR reaction, how many copies of the target will be present after three rounds of amplification?
Immediately after the primers have annealed to the target sequence, ______________.
The temperature is raised so that taq polymerase can extend the primers
To produce a DNA fragment that contains the whole gene and has two sticky ends, where must the enzyme's restriction sites be located?
outside the gene on both sides, but not inside the gene
A complete set of clones is called a ___________
plasmid library
The products of restriction digestion can be visualized by gel electrophoresis, which separates fragments based on their size. True/False??
A 1.5‑kb fragment of DNA is cloned into a plasmid vector that is 5.5 kb long at the EcoRI site, and the plasmid vector is then used to transform bacteria. If the plasmid DNA is then extracted from a single bacterial colony and digested with EcoRI, what digestion products will be produced if the plasmid contains the fragment?
One 1.5‑kb fragment and one 5.5‑kb fragment
Digestion of a 1.1‑kb fragment of DNA with BamHI produces two fragments of 700 bp and 400 bp. Digestion of the same 1.1‑kb fragment with XhoI produces two fragments of 300 bp and 800 bp. Digestion with both enzymes produces three fragments of 100 bp, 300 bp, and 700 bp. Which of the following statements is true about the DNA fragment?
The XhoI site is located within the BamHI 400‑bp fragment.
Which of the following statements about ddNTPs is true?
They have a hydrogen at the 3′ carbon of the ribose sugar
DNA fragments that are 600 bp long will migrate more quickly through a sequencing gel than fragments that are 150 bp long. True/False???
Which of the following statements about manual Sanger sequencing is true?
The DNA sequence obtained is complementary to the template strand.
An RFLP marker that cosegegrates with a disorder exists in most people who have the disorder and is absent in most people who don't have the disorder. True/False??
A portion of the β‑globin allele responsible for sickle‑cell anemia contains the sequence CCTGTGGAG, whereas the same region of the normal β‑globin allele contains the sequence CCTGAGGAG. Which allele would be cut by the restriction enzyme DdeI, which cuts at the sequence CTNAG, where N is any base?
Only the normal allele will be cut
The mutation resulting in the allele for sickle‑cell anemia removes a restriction site from the β‑globin gene such that a specific probe hybridizes to one 1.3‑kb fragment instead of two fragments of 1.1 kb and 0.2 kb. What restriction pattern will be seen in sickle‑cell carriers?
Three fragments of 1.3, 1.1, and 0.2 kb
There are an unlimited number of VNTR alleles for each locus, such that every individual has unique alleles at each VNTR locus. True/False???
Why are multiple VNTR probes used in DNA fingerprinting?
They increase the probability of producing a DNA fingerprint that is unique to an individual.
If four different VNTR alleles have frequencies of 1 in 10, 1 in 20, 1 in 50, and 1 in 500 in a population of 250 million, how many people would have all four alleles?
Which proteins would you expect to find associated with eukaryotic chromosomes?
In what type of chromatin would you expect to find genes that are actively transcribed?
Which of the following class of enzymes add or remove rotations to DNA?
Identify the correct order of organization, from least condensed to more condensed.
double stranded helix, nucleosome, 30 nm fiber, chromosome
How many bands of DNA would be expected in Meselson and Stahl's experiment after two rounds of conservative replication?
The DNA template for eukaryotic replication is ________ while the DNA template in Theta replication is _______.
linear, circular
Which activity is not associated with DNA polymerases?
5' to 3' synthesis of new strands
The activity of which enzyme would be needed latest in DNA synthesis?
DNA polymerase
The following enzyme travels ahead of the replication fork and removes strain introduced by unwinding of the DNA
This protein synthesizes a short RNA primer to provide a 3'OH group for the attachment of DNA nucleotides.
When this molecule is synthesized, both strands of DNA are used as a template
DNA only
This molecule is synthesized using triphosphate nucleotides as a substrate for a polymerase enzyme that forms phosphodiester bonds
Both RNA and DNA
This molecule is synthesized using nucleotides containing the bases adenine, guanine, cytosine, and uracil
RNA only
The polymerase that synthesizes this molecule uses DNA as a template and synthesizes new strands from 5' to 3'.
Both RNA and DNA
This molecule is made of nucleotides joined by phosphodiester bonds that connect the 2' OH group to the 5' phosphate
DNA only
Which of the following mechanisms is not used by cells to ensure the fidelity of DNA synthesis?
nucleotide selection
When RNA is transcribed from a gene, which strand of DNA is used?
the template strand
What would the result be if a specific sigma subunit were mutated?
RNA polymerase would still bind at specific sites, but elongation would fail
If and mRNA is hybridized to DNA and we observe loops of noncoding DNA that are not hybridized to DNA, what might we conclude?
The gene and protein are not collinear
What is the most likely result from mutating a prokaryotic Shine-Delgarno sequence?
the ribosome would not be able to bind to the mRNA
An RNA with catalytic properties is called a ____________
Which of the following classes of RNA is found only in eukaryotes?
small interfering RNA
From 5' to 3', what is the correct order of the three main regions of a transcription unit?
terminator, RNA coding region, promoter
________ genes are collinear while _______ genes are not
constitutive, regulated
Identify the correct order events that occur during the processing of eukaryotic mRNA.
Intron splicing, 3'poly-A addition, 5' cap addition
How do double-stranded RNAs silence gene expression?
inhibition of translation and message degradation
Which mRNA processing event adds stability to the mRNA?
addition of a 5' cap and addition of a ploy (A) tail to the 3' end
Which of the following is not necessary for RNA polymerase to recognize the promoter of a bacterial gene?
origin of replication
If there were five nucleotides per codon, how many possible combinations are possible?
Which statement about the genetic code is not true?
some amino acids are specified by more than one codon
When codons that code for the same amino acid differ in their _____, a single tRNA might bind both of them through wobble base pairing.
3' base
What is the enzyme responsible for tRNA charging?
tRNA synthetase
what component is the first to bind to mRNA?
small ribosomal subunit
What would be the effect on translation of a single nucleotide deletion in the RNA coding region of a gene
The reading frame downstream of the deletion would be altered
What is the correct progression of tRNAs through the ribosome?
What molecule provides energy for protein synthesis in bacterial cells?
The amino acid encoded by the initiation codon in eukaryotes is _______ and in _______ in prokaryotes
N-formylmethionine, N-formylmethionine
What tRNA binds to the termination codon, 5'UAA3'?
The genetic code is said to be degenerate because
there are more codons than amino acids
Which is a mechanism that allows a single gene to encode more than one polypeptide?
alternative RNA splicing