Question 1

Why might a change in its amino acid sequence lead to a change in the way a protein functions?

Accepted Answer

The sequence of amino acids in a protein determines its three-dimensional shape, which is critical to its function. If there are changes in the sequence, it may result in a misfolded protein that cannot function normally.

Question 2

Amino acid sequences result from the process of

Accepted Answer

Amino acid sequences are produced through the process of translation, in which the sequence of nucleotides in mRNA is used to specify the sequence of amino acids in a protein. Transcription involves the synthesis of mRNA from DNA, replication refers to the copying of DNA, regulation involves control of gene expression, and complementary base pairing is the basis of DNA replication and transcription.

Question 3

Do all mutations that occur within the DNA sequence result in abnormal protein expression,and therefore affect the function of the protein?

Accepted Answer

Mutations within the noncoding regions of the DNA sequence do not affect overall protein structure and DNA repair enzymes are designed specifically to "proofread" the DNA and catch most mistakes. Therefore, not all mutations lead to abnormal protein expression and function.

Question 4

Why should pregnant women never be given X-rays?

Accepted Answer

The answer of Why should pregnant women never be given...

Question 5

The number of errors made by DNA polymerase during DNA replication that pass though the cell's repair checkpoints is estimated at

Accepted Answer

DNA polymerase has a high fidelity, and the error rate that passes through repair mechanisms is approximately 1 in 1,000,000,000 bases.

Question 6

Which of the following cannot lead to a mutation?

Accepted Answer

Replacing thymine with uracil when making RNA is a normal process that occurs during RNA transcription and does not lead to a mutation. However, the other options involve alterations to the DNA sequence, which can potentially cause a mutation.

Question 7

Doctors will screen individuals with a strong family history of breast cancer for mutations in the BRCA1 gene.Explain why someone who does not test positive for a mutation can still be at risk for a BRCA1 mutation and breast cancer.

Accepted Answer

The answer of Doctors will screen individuals with a strong...

Question 8

Mutations in DNA sequences may occur during the process of

Accepted Answer

Mutations occur during replication when DNA is being copied. Transcription and translation are processes involved in protein synthesis, but they do not involve the replication of DNA. Tumor suppression and apoptosis are not directly related to the process of DNA replication.

Question 9

DNA damage is usually repaired

Accepted Answer

DNA damage is usually repaired at or before checkpoints in the cell cycle. Checkpoints are stages in the cell cycle where the cell "checks" the integrity of its DNA before proceeding to the next stage. If any damage is detected, the cell will trigger repair mechanisms to fix the damage before continuing with the cell cycle. If the damage cannot be repaired, the cell may undergo apoptosis (programmed cell death) to prevent the damaged DNA from being passed on to daughter cells.

Question 10

What would happen if the enzyme that makes DNA added a nucleotide to the middle of a coding region of a gene?

Accepted Answer

Adding a nucleotide in the middle of a coding region would shift the reading frame of the DNA sequence, meaning that all subsequent codons would be read differently. This would likely result in a different amino acid sequence of the protein produced, which could have deleterious effects on its function.

Question 11

How often do mistakes occur when copying DNA? Do all these mistakes appear in the final,copied DNA?

Accepted Answer

The answer of How often do mistakes occur when copying...

Question 12

Mutations are

Accepted Answer

Mutations can have various effects on an organism's fitness. Some mutations may be harmful, causing a decrease in fitness, while others may be beneficial, increasing fitness. However, some mutations may not affect fitness at all and are considered neutral. Therefore, mutations can be harmful, helpful, or have no effect on an organism's fitness, making option E the correct choice.

Question 13

Radioactive Man,a comic-book superhero,gained his abilities by falling into a vat of industrial toxic waste.Is this a likely outcome?

Accepted Answer

Choice B is correct because most mutations are indeed either harmful or neutral. Choice D is also correct because exposure to toxic waste could indeed cause cancer or other diseases. Therefore, the most likely outcome of falling into a vat of industrial toxic waste would not be the acquisition of superpowers, but rather severe health consequences.

Question 14

Which sequence is the complementary DNA sequence of ATG GGC CTG?

Accepted Answer

The complementary DNA sequence is formed by pairing each nucleotide with its complementary base: A with T, T with A, C with G, and G with C. Thus, the complementary sequence for ATG GGC CTG would be TAC CCG GAC, as A pairs with T, T pairs with A, C pairs with G, and G pairs with C. Option A is the original sequence, and option B has an incorrect middle section. Option C has an incorrect base and includes an incorrect symbol (TUC). Option E has an incorrect base pair in the initial sequence.

Question 15

The enzyme that copies DNA makes a mistake approximately every 10,000 to 100,000 bases.Surprisingly,however,if we examine newly copied DNA,we see that the actual error rate is lower than this.How is that possible?

Accepted Answer

There are other enzymes that find errors in DNA and repair them. These enzymes proofread the newly copied DNA and repair any mistakes that were made during replication. This ensures that the error rate in the final DNA product is lower than the mistake rate of the replicating enzyme alone.

Question 16

A mutation would most likely be inherited if it is located in a ____ cell.

Accepted Answer

Mutations in somatic cells (such as skin or liver cells) occur after an organism is already formed and cannot be passed on to offspring. Mutations in germ cells (such as sperm cells) can be inherited because they are present in the cells used to create offspring.

Question 17

Substitution of a nucleotide base in the coding sequence of a gene may alter the protein's

Accepted Answer

Substitution of a nucleotide base in the coding sequence of a gene can lead to changes in the amino acid sequence of the resulting protein, which can ultimately affect its 3D shape, folding, and function. Therefore, all of the above choices are correct.

Question 18

Why aren't all mutations that occur in DNA inherited by our offspring?

Accepted Answer

Only mutations in the DNA contained in the sperm and eggs will be inherited because these cells contain the genetic material that is passed on to offspring during reproduction. Mutations that occur in other cells of the body are not passed on to offspring because they are not involved in the production of gametes.

Question 19

Which sequence is a result of a single mismatch in DNA replication of the sequence ATG GGC CTG?

Accepted Answer

The answer of Which sequence is a result of a...

Question 20

DNA mutations can

Accepted Answer

DNA mutations can have various effects, including being detrimental (leading to genetic diseases or disorders), being beneficial (resulting in increased survival or adaptation to changing environments), or having no effect (depending on the location and degree of the mutation). Therefore, choice D, which states that mutations can have all of these effects, is the best choice.

Quiz 10: Mutations and Cancer Fighting Fate