MBG 2040 Lecture Notes - Lecture 27: Reading Frame, Chain Termination, Peptide
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QUESTION 1. Choose the true statement about prokaryotic and eukaryotic DNA replication. A.Eukaryotic DNA replication involves less protein factors than does prokaryotic DNA replication. |
B. Prokaryotic DNA polymerases replicate DNA 5' to 3', while eukaryotic DNA polymerases replicate DNA 3' to 5'. |
C. Eukaryotic DNA replication begins at multiple origins of replication, while prokaryotic DNA replication begins at a single origin of replication. |
D. Prokaryotic genomes take longer to replicate than eukaryotic genomes. |
QUESTION 2. Bacterial cells use DNA replication to:
A. make back-up copies of their genome in case of a mutation. |
B. manifest multiple phenotypes at once. |
C. copy their genetic material prior to binary fission. |
D. build functional proteins. |
QUESTION 3. Choose the true statement about the genetic code.
A. A cell's mRNA code is read four nucleotides at a time to specify a single amino acid. |
B. The genetic code encodes 64 amino acids, one for each of the 64 corresponding codons. |
C. The genetic code is redundant, with multiple codons specifying a single amino acid. |
D. The genetic code varies widely among organisms, with each having a different set of codons for a corresponding amino acid. |
QUESTION 4. Of the following enzymes, which are correctly matched with their function? To be marked correct, you'll need to select all correctly matched statements, as there may be more than one correct answer.
A. Helicase, relieves torsion stress as DNA unwinds |
B. Ligase, covalently bonds adjacent Okazaki fragments |
C. Primase, removes RNA primers |
D. DNA polymerase III, builds most of the DNA on the leading and lagging strand |
QUESTION 5. Which of the following contributes to DNA replication accuracy? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.
A. The capacity to proofread improves DNA replication accuracy. |
B. A slow rate of DNA replication contributes to accuracy. |
C. The use of primase improves DNA replication accuracy. |
D. DNA replication accuracy is improved thanks to complementary base pairing rules. |
Fill in the blank. Elongation during translation does NOT involve ____________.
Question 16 options:
the translation of codons according to the genetic code | |
the formation of bonds catalyzed by the ribosome | |
complementary base pairing between RNA molecules | |
amino acids being linked together in a polypeptide | |
reading the DNA template 3' to 5' |
For a given gene, what establishes the reading frame for translation?
Question 17 options:
the location of the enhancer relative to the gene | |
the first three nucleotides at the 5' end of the mRNA | |
the first three nucleotides at the 3' end of the mRNA | |
the start codon in the mRNA | |
the location of the promoter relative to the gene |
Which of the following is the LEAST likely direct consequence of a substitution mutation?
Question 18 options:
changing the length of a protein coded for by a gene | |
changing one amino acid in a protein | |
creating a stop codon | |
eliminating a start codon | |
changing the length of the DNA molecule containing a gene |
Suppose that the pre-mRNA transcript from a eukaryotic gene is 30,000 nucleotides long, and the gene codes for a sequence of 300 amino acids. What is the best explanation for the relationship between these numbers?
Question 19 options:
only the first 900 nucleotides of the pre-mRNA transcript are translated | |
it takes 100 nucleotides to specify a single amino acid | |
300 of the nucleotides in the transcript are important, and the rest are "junk" | |
only the last 900 nucleotides of the pre-mRNA transcript are translated | |
large portions of pre-mRNA transcripts are cut out during RNA processing |
Suppose an individual is born into a population with a novel mutation. Is the new mutation an evolutionary change, and why?
Question 20 options:
no, because it is not a big enough change to count | |
yes, because new mutations are always adaptive | |
yes, because the appearance of a new genetic variant is a genetic change in a population | |
no, because not enough individuals have the mutation for it to matter | |
no, because most mutations are not adaptive |
Part B
Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why?
a) It could cause a frameshift nonsense or frameshift missense mutation because it would change the reading frame of the codon triplet. | ||||||||||||||||||||||||||||
b) It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one. | ||||||||||||||||||||||||||||
c) It could cause a nonsense mutation because the sequence would no longer be the same, so the protein would be shorter and non-functional. | ||||||||||||||||||||||||||||
d) It could cause a silent mutation because A and T are complementary to each other so it is not really a substitution mutation. Part C Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein?
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