ASU BIO 181 Unit 2 Genetic Mutations Learnsmart Notes

What is a base substitution? A mutation that affects only one base pair The change of a single amino acid in a polypeptide sequence A mutation that occurs when one base is replaced by another Addition or deletion of a single base The change of a normal codon to a stop codon

A mutation that occurs when one base is replaced by another

Multiple Select Question Select all that apply Which of the following are ways that point mutations may alter a gene? A nucleotide is added to a gene. The total chromosome number is changed. A base pair is removed from a gene. The base sequence within the gene is changed.

A nucleotide is added to a gene. A base pair is removed from a gene. The base sequence within the gene is changed.

Multiple Select Question Select all that apply What are the typical functions of proteins encoded by genes that may become oncogenes? Transcription factor Growth factor receptor Protein that activates apoptosis DNA repair enzyme Intracellular signaling protein Cell cycle checkpoint protein

Transcription factor Growth factor receptor Intracellular signaling protein

Multiple Select Question Select all that apply What are the typical functions of proteins encoded by genes that may become oncogenes? Transcription factor Intracellular signaling protein Growth factor receptor Cell cycle checkpoint protein Protein that activates apoptosis DNA repair enzyme

Transcription factor Intracellular signaling protein Growth factor receptor

A silent mutation results in a polypeptide with an unchanged amino acid sequence because the genetic code is: degenerate. universal. ambiguous.

degenerate.

Relatively small changes in DNA sequence are known as: mutagens. gene mutations. transposable elements. nucleotides. splice junctions.

gene mutations.

Gametes are produced by: somatic cells. all organisms. all human cells. germ line cells.

germ line cells.

Multiple Select Question Select all that apply Which of the following are ways that point mutations may alter a gene? A nucleotide is added to a gene. A base pair is removed from a gene. The total chromosome number is changed. The base sequence within the gene is changed.

A nucleotide is added to a gene. A base pair is removed from a gene. The base sequence within the gene is changed.

Which of the following organisms have the ability to repair DNA and thus minimize mutations? All eukaryotes All living things Only animals and plants All prokaryotes

All living things

Multiple Select Question Select all that apply How do point mutations affect DNA sequences? By reinserting a portion of the sequence in reverse order By adding or subtracting a single base pair By rearrangement of nucleotides By inserting a sequence of multiple base pairs into the existing DNA molecule By substituting one base for another

By adding or subtracting a single base pair By substituting one base for another

Multiple Select Question Select all that apply How do point mutations affect DNA sequences? By inserting a sequence of multiple base pairs into the existing DNA molecule By substituting one base for another By reinserting a portion of the sequence in reverse order By rearrangement of nucleotides By adding or subtracting a single base pair

By substituting one base for another By adding or subtracting a single base pair

What type of mutation is the result of the insertion or removal of nucleotides that does not occur in multiples of three? Nonsense Frameshift Silent Missense

Frameshift

What type of mutation changes a single amino acid in a polypeptide sequence? Silent Missense Frameshift Nonsense

Missense

Multiple Select Question Select all that apply What are the two main functions of tumor suppressor genes? Positive regulation of cell division Negative regulation of apoptosis Negative regulation of cell division Maintenance of genome integrity

Negative regulation of cell division Maintenance of genome integrity

What type of mutation changes a normal codon to a termination codon? Silent Missense Nonsense Frameshift

Nonsense

How does a frameshift mutation affect protein function? It may have either a neutral or negative effect on protein function depending on the amino acid that is now encoded. It will likely inhibit protein function because the codon for an amino acid is changed to a stop codon, which will result in a truncated polypeptide. Protein function is most likely inhibited because an entirely new amino acid sequence occurs downstream of the mutation. Protein function is not affected because the mutation does not change the amino acid that is encoded.

Protein function is most likely inhibited because an entirely new amino acid sequence occurs downstream of the mutation.

What type of mutation has no effect on the amino acid sequence of a polypeptide? Missense Neutral Frameshift Nonsense Silent

Silent

What type of mutation results from abnormalities that naturally occur during biological processes? Spontaneous Frameshift Silent Induced

Spontaneous

What type of mutation results from abnormalities that naturally occur during biological processes? Spontaneous Silent Frameshift Induced

Spontaneous

What missense mutation is least likely to affect protein function? Substitution of a negatively charged amino acid for a positively charged one Substitution of a positively charged amino acid for another positively charged amino acid Substitution of a positively charged amino acid with one that is neutral Substitution of a positively charged amino acid for a negatively charged one

Substitution of a positively charged amino acid for another positively charged amino acid

Where must a mutation occur if it is to directly affect an amino acid sequence? An operator site The coding region of a protein-encoding gene The intergenic region Transcriptional regulatory elements The promoter of a gene

The coding region of a protein-encoding gene

How do somatic mutations affect an individual's offspring? The mutation occurs only in the germ line cells and is passed on to all of the individual's offspring. The mutation does not occur in germ line cells and therefore does not affect offspring. The mutation is present in all cells of the individual's body, including germ line cells. Therefore, the mutation is passed to all offspring. The mutation occurs only in the germ line cells and is passed on to half of the individual's offspring.

The mutation does not occur in germ line cells and therefore does not affect offspring.

What does a gene mutation affect? The overall structure of a chromosome The sequence of bases in a particular gene The total number of chromosomes

The sequence of bases in a particular gene

How do nonsense mutations affect protein function? The amino acid sequence is altered after the site of the mutation, completely changing the structure and function of the polypeptide. Because multiple codons can specify the same amino acid, the base substitution does not affect protein structure or function. Translation is terminated where the mutation occurs, producing a truncated polypeptide which is unlikely to function correctly. The effect on protein function may be neutral or negative, depending on how similar the substituted amino acid is to the original.

Translation is terminated where the mutation occurs, producing a truncated polypeptide which is unlikely to function correctly.

T/F: A somatic mutation is not transmitted to the offspring of the individual that carries it.

True Reason: Because it does not occur in the germ line cells of the individual, a somatic mutation does not affect the offspring.

A missense mutation may not affect protein structure and function if the altered amino acid has: changed to a stop codon. a similar side chain. a different side chain.

a similar side chain.

Consider a normal gene that is needed for growth. If this gene becomes overactive, it may contribute to cancer. It then becomes a(n): p53 gene. homeobox gene. tumor-suppressor gene. oncogene.

oncogene.

Over the past four decades, researchers have identified many types of ______________. Examples include growth factor receptors, transcription factors, and intracellular signaling proteins. oncogenes pseudogenes tumor-suppressor genes DNA-repair genes

oncogenes

When oncogenes are ___________ compared to proto-oncogenes, they can promote certain types of cancer. overactive underactive inactive

overactive

Silent mutations have no effect on the amino acid sequence of a polypeptide because: mRNA does not recognize the base substitution, so the same polypeptide is produced during translation. the mutation changes only a single amino acid in the polypeptide sequence. although a base substitution occurs, the nucleotide excision repair system restores it to the original. the base substitution results in a codon that specifies the same amino acid as the original sequence.

the base substitution results in a codon that specifies the same amino acid as the original sequence.

Somatic mutations are not transmitted to an individual's offspring because: they are eliminated by natural selection. they do not occur in the gametes. they occur after an individual has already reproduced.

they do not occur in the gametes.

Maintenance of genome integrity and negative regulation of cell division are the two main functions of ___________. homeobox genes oncogenes tumor-suppressor genes proto-oncogenes

tumor-suppressor genes