Question 1

Given the DNA template strand: TAC CGT TTT AAC TTC TTC AAA CCC ACT, what is the correct mRNA sequence produced during transcription?

Accepted Answer

AUG GCA AAA UUG AAG AAG UUU GGG UGA

Question 2

Using the mRNA sequence AUG GCA AAA UUG AAG AAG UUU GGG UGA, what is the resulting amino acid sequence (protein) after translation?

Accepted Answer

Met-Ala-Lys-Leu-Lys-Lys-Phe-Gly-Stop

Question 3

A substitution mutation changes the DNA template from TAC CGT TTT AAC TTC TTC AAA CCC ACT to TAC CGT TTT AAC TTC TTA AAA CCC ACT. What type of mutation is this?

Accepted Answer

Synonymous (silent) mutation

Question 4

If a single base insertion occurs early in a gene sequence, what is the most likely effect on the resulting protein?

Accepted Answer

It will cause a frameshift, likely resulting in a nonfunctional protein.

Question 5

Which of the following best describes a nonsynonymous mutation?

Accepted Answer

A nucleotide change that alters the amino acid sequence of a protein.

Question 6

Given the following scenario: In a gene, the ratio $$N/S \u003e 1 ($$where $$N is $$the number of nonsynonymous mutations and $$S is $$the number of synonymous mutations). What does this suggest about natural selection on this gene?

Accepted Answer

Positive selection for advantageous mutations

Question 7

A DNA template strand for melanin production in a population is TAC CGT TTG AAA GGG TTC ACT. What is the mRNA and protein sequence produced?

Accepted Answer

mRNA: AUG GCA AAC UUU CCC AAG UGA; Protein: Met-Ala-Asn-Phe-Pro-Lys-Stop

Question 8

If a gene in a population has a high rate of synonymous mutations compared to nonsynonymous mutations ($$N/S \u003c 1$$), what does this indicate about the evolutionary forces acting on the gene?

Accepted Answer

Negative selection is acting against amino acid changes

Question 9

A mutation changes the codon UUU (Phe) to UUC (Phe). What type of mutation is this and what is its likely effect?

Accepted Answer

Synonymous (silent) mutation; no change in protein

Question 10

In a population, a gene for melanin production has the template DNA: TAC CCC TAT AAA GGG TTC ACT. What is the mRNA and protein sequence produced?

Accepted Answer

mRNA: AUG GGG AUA UUU CCC AAG UGA; Protein: Met-Gly-Ile-Phe-Pro-Lys-Stop

Question 11

A population of birds has a gene with the following ancestor sequence: TAC ATT AAA CCT TTA TTC ATA TAA. In a derived population, the gene is TAC ATT ATA CCT TTA TTC ATA TTA. If the change is in the third position of a codon, what type of mutation is this most likely to be?

Accepted Answer

Synonymous (silent) mutation

Question 12

Why are insertions or deletions (indels) generally more harmful to protein function than single base substitutions?

Accepted Answer

They cause frameshifts, altering the reading frame and potentially changing every amino acid downstream.

Question 13

A mutation in the third base of a codon often results in which of the following?

Accepted Answer

A synonymous (silent) mutation

Question 14

If a population shows evidence of positive selection on a gene, what would you expect the ratio of nonsynonymous to synonymous mutations ($$N/S) to be$$?

Accepted Answer

$$N/S \u003e 1$$

Question 15

A gene sequence is mutated such that a codon changes from UGG (Trp) to UGA (Stop). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 16

In a real-world scenario, a patient has a genetic disorder caused by a single base substitution that changes a codon from GAA (Glu) to GUA (Val). What type of mutation is this and what is its likely effect?

Accepted Answer

Nonsynonymous (missense) mutation; changes the amino acid and may affect protein function

Question 17

A researcher finds that a gene in a population has a high number of nonsynonymous mutations and the population is thriving. What does this suggest about the evolutionary history of this gene?

Accepted Answer

Positive selection has favored changes in the protein sequence

Question 18

If a codon in the mRNA changes from AAA (Lys) to AGA (Arg), what is the effect on the protein and what type of mutation is this?

Accepted Answer

Amino acid changes from Lys to Arg; nonsynonymous (missense) mutation

Question 19

A population of birds is found to have a gene with $$N/S \u003c 1$$ for color vision. What does this suggest about the evolutionary pressure on this gene?

Accepted Answer

Negative selection is acting to conserve the protein sequence

Genetic Mutations, Protein Synthesis, and Molecular Evolution: Study Notes

Guida di studio - Domande di pratica

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