Biology 7.3 Mutation and Mutagens

Questions and Answers

Define mutation and mutagen.

Mutation - A change in a gene or chromosome; Mutagen - A chemical or physical agent that interacts with DNA and causes a mutation.

List three examples of mutagens.

UV radiation, X-rays, cigarette smoke.

Identify three types of chromosomal alterations.

Duplication, inversion, insertion.

Distinguish among silent, missense, and nonsense point mutations.

Silent mutation - does not change the amino acid; Missense mutation - changes one amino acid; Nonsense mutation - introduces a stop codon. Signup and view all the answers

What is a frameshift mutation? What causes this type of mutation?

Frameshift mutation - A genetic mutation caused by indels (insertions or deletions). Signup and view all the answers

Assume that a point mutation changes the codon AUU to AUC. Why is this a neutral mutation?

It is a silent mutation. Signup and view all the answers

Describe how the insertion of A after the start codon AUG affects the encoded amino acid sequence: AUG-GUC-CCU-AAA !AUG-AGU-CCC-UAA-A.

The insertion causes a change in the amino acid sequence leading to an altered protein. Signup and view all the answers

Compare and contrast germline mutations and somatic mutations.

Germline mutations occur in germ cells; somatic mutations occur in body cells. Signup and view all the answers

Study Notes

Mutations and Mutagens

Mutation: A change in a gene or chromosome that can affect an organism's traits.
Mutagen: A chemical or physical agent that interacts with DNA, leading to mutations.

Examples of Mutagens

UV Radiation: High-energy light that can cause DNA damage.
X-rays: A form of radiation that can lead to genetic alterations.
Cigarette Smoke: Contains harmful chemicals that can cause mutations.

Chromosomal Alterations

Duplication: A segment of the chromosome is repeated, leading to extra genetic material.
Inversion: A segment of the chromosome breaks off, flips around, and reattaches, altering gene order.
Insertion: Extra DNA is added into a gene sequence, which can disrupt normal function.

Point Mutations

Silent Mutation: A change in the nucleotide that does not alter the amino acid sequence due to redundancy in genetic code.
Missense Mutation: A change that results in the substitution of one amino acid for another, potentially impacting protein function.
Nonsense Mutation: A change that introduces a premature stop codon, leading to truncated proteins.

Frameshift Mutation

Definition: A genetic mutation resulting from insertions or deletions (indels) of nucleotides, which alters the reading frame of the gene.
Causes: Indels that shift the normal grouping of codons.

Neutral Mutation

Changing the codon from AUU to AUC may result in a silent mutation, which does not affect the protein's function since both codons code for the same amino acid (Isoleucine).

Effects of Insertion Mutation

Insertion after the start codon (AUG) can lead to a missense mutation, altering the encoded amino acid sequence from AUG-GUC-CCU-AAA to AUG-AGU-CCC-UAA.

Germline vs. Somatic Mutations

Germline Mutations: Occur in germ cells (sperm and egg), can be passed to offspring, leading to hereditary conditions.
Somatic Mutations: Occur in body cells and are not inherited, affecting only the individual organism.

Description

Test your knowledge on mutations and mutagens with these flashcards. Explore definitions, examples of mutagens, and types of chromosomal alterations. Perfect for reviewing key concepts in biology chapter 7.3.