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Problem 46
The codons UGA, UAA, and UAG do not code for amino acids. What is their role as codons in mRNA?
Problem 47
What is the difference between a codon and an anticodon?
Problem 48
Why are there at least 20 different tRNAs?
Problem 49
What are the three steps of translation?
Problem 50
Where does protein synthesis take place?
Problem 51a
Use three-letter and one-letter abbreviations to write the amino acid sequence for the peptide from each of the following mRNA sequences:
a. ACC ACA ACU
Problem 51c
Use three-letter and one-letter abbreviations to write the amino acid sequence for the peptide from each of the following mRNA sequences:
c. UAC GGG AGA UGU
Problem 52c
Use three-letter and one-letter abbreviations to write the amino acid sequence for the peptide from each of the following mRNA sequences:
c. AUG CAC AAG GAA GUA CUG
Problem 56b
The following sequence is a portion of the DNA template strand: TGT GGG GTT ATT
b. What are the anticodons of the tRNAs?
Problem 57b
The following is a segment of the DNA template that codes for human insulin: TTT GTG AAC CAA CAC CTG
b. Write the three-letter and one-letter abbreviations for this corresponding peptide segment.
Problem 61
What is the effect of a deletion mutation on the amino acid sequence of a polypeptide?
Problem 63
How is protein synthesis affected if the normal base sequence TTT in the DNA template strand is changed to TTC?
Problem 65a
Consider the following segment of mRNA produced by the normal order of DNA nucleotides:
ACA UCA CGG GUA
a. What is the amino acid order produced from this mRNA?
Problem 65b
Consider the following segment of mRNA produced by the normal order of DNA nucleotides:
ACA UCA CGG GUA
b. What is the amino acid order if a point mutation changes UCA to ACA?
Problem 65e
Consider the following segment of mRNA produced by the normal order of DNA nucleotides:
ACA UCA CGG GUA
e. What is the amino acid order if an insertion mutation adds a G to the beginning of the mRNA segment?
Problem 65f
Consider the following segment of mRNA produced by the normal order of DNA nucleotides:
ACA UCA CGG GUA
f. What is the amino acid order if a deletion mutation removes the A at the beginning of the mRNA segment?
Problem 67a
A point mutation changes a codon in the mRNA for an enzyme from GCC to GCA. Why is there no change in the amino acid order in the protein?
Problem 67b
In sickle-cell anemia, a point mutation in the mRNA for hemoglobin results in the replacement of glutamate with valine in the resulting hemoglobin molecule. Why does the replacement of one amino acid cause such a drastic change in biological function?
Problem 68a
A point mutation in the mRNA for an enzyme results in the replacement of leucine with alanine in the resulting enzyme molecule. Why does this change in amino acids have little effect on the biological activity of the enzyme?
Problem 73
How is a gene for a particular protein inserted into a plasmid?
Problem 79a
A specific virus contains RNA as its genetic material.
a. Why would reverse transcription be used in the life cycle of this type of virus?
Problem 79b
A specific virus contains RNA as its genetic material.
b. What is the name of this type of virus?
Problem 82
How do protease inhibitors disrupt the life cycle of the HIV virus?
Problem 87a
The following is a segment of the template strand of human BRCA1 gene:
TGG AAT TAT CTG CTC TTC GCG
a. Write the corresponding mRNA segment.
Problem 87b
The following is a segment of the template strand of human BRCA1 gene:
TGG AAT TAT CTG CTC TTC GCG
b. Write the three-letter and one-letter abbreviations for the corresponding peptide segment.
Problem 87c
The following is a segment of the template strand of human BRCA1 gene:
TGG AAT TAT CTG CTC TTC GCG
c. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?
Problem 89a
Answer the following questions for the given section of DNA:
a. Complete the bases in the parent and new strands.
Problem 89b
Answer the following questions for the given section of DNA:
b. Using the new strand as a template, write the mRNA sequence.
Problem 89c
Answer the following questions for the given section of DNA:
c. Write the three-letter symbols for the amino acids that would go into the peptide from the mRNA you wrote in part b.
Problem 90a
Suppose a mutation occurs in the DNA section in problem 17.89, and the first base in the parent chain, adenine, is replaced by guanine.
a. What type of mutation has occurred?
