bio 3201 topic 8 & 9

What is a somatic cell mutation?

A mutation that occurs in body cells; affects only the individual and is not inherited.

What is a germline mutation?

A mutation that occurs in reproductive cells (sperm or egg) and can be passed to offspring.

Which type of mutation is heritable?

Germline mutations.

What is a point mutation?

A chemical change that affects one or a few nucleotides in DNA.

What are the three types of point mutations?

Substitution, insertion, deletion.

What is a substitution mutation?

One nucleotide is replaced with another.

What is an insertion mutation?

One or more nucleotides are added to a DNA sequence.

What is a deletion mutation?

One or more nucleotides are removed from a DNA sequence.

Which point mutations cause frameshifts?

Insertions and deletions.

What is a frameshift mutation?

A mutation that shifts the reading frame of a gene, altering all downstream codons.

Why are frameshift mutations often harmful?

They change many amino acids and usually produce a nonfunctional protein.

Why do some substitutions have no effect?

Due to redundancy of the genetic code.

What is a silent mutation?

A mutation that does not change the amino acid sequence.

What is a missense mutation?

A mutation that changes one amino acid in a protein.

What disease is caused by a missense mutation in hemoglobin?

Sickle cell disease.

What is a nonsense mutation?

A mutation that introduces a premature stop codon.

Which mutation usually results from a frameshift?

Nonsense mutation.

What is a chromosomal mutation?

A mutation involving large segments of chromosomes.

What is a deletion mutation?

Loss of a chromosome segment.

What is a duplication mutation?

A chromosome segment is repeated.

What is an inversion mutation?

A chromosome segment is reversed.

What is a translocation mutation?

A chromosome segment moves to a non-homologous chromosome.

What is nondisjunction?

Failure of chromosomes to separate properly during meiosis.

What is aneuploidy?

An abnormal number of chromosomes.

What is a spontaneous mutation?

A mutation that occurs naturally due to errors in DNA replication.

What is an induced mutation?

A mutation caused by environmental agents.

What is a mutagen?

A substance or event that increases the mutation rate.

Give examples of physical mutagens.

UV radiation, X-rays.

Give examples of chemical mutagens.

Carcinogens, tobacco smoke, pesticides.

What is epigenetics?

The study of changes in gene expression without altering DNA sequence.

Are epigenetic changes reversible?

Yes.

How does epigenetics explain different cell types?

Genes are turned on or off in different cells.