chp. 15A: mutation

What is a thymine dimer?

A site where two adjacent thymine bases become covalently cross-linked to each other

Which of the following are ways that mutations may alter a gene?

By changing the base sequence within a gene By adding or subtracting a single base pair

How does a missense mutation cause red blood cells to sickle?

Glutamic acid is changed to valine, altering the structure of the hemoglobin protein and causing the hemoglobin subunits to stick to one another.

What does a gene mutation affect?

The sequence of bases of a particular gene

Sickle cell disease is caused by a missense mutation that affects which of the following?

The structure of the hemoglobin protein The tendency of hemoglobin proteins to aggregate when the oxygen concentration is low The shape of red blood cells

A mutation may affect the amino acid sequence of a polypeptide only if it occurs within the

coding sequence of a structural gene.

Mutations that occur in noncoding sequences may affect gene

expression

Which of the following are examples of ionizing radiation?

gamma rays and x-rays

A mutation is best defined as:

heritable change in genetic material

A specific type of point mutation involves a base substitution that changes a single amino acid in a polypeptide sequence. This is called a(n) _____ mutation.

missense

What type of mutation changes a single amino acid in a polypeptide sequence?

missense

Point mutations cause two basic types of changes to a gene: (1) The base sequence within a gene can ______ ; and (2) one base pair can be added to or removed from a gene.

modified

Agents that cause mutation are known as

mutagens

X-rays and ultraviolet light are examples of _____ mutagens

physical

What is a mutagen?

physical or chemical agent that causes mutations

What type of mutation results from abnormalities that naturally occur during biological processes?

spontaneous

A mutated site in DNA where two adjacent thymine bases become covalently cross-linked to one another is termed a(n)

thymine dimer

Ultraviolet light can cause the formation of a(n) _____ ______ in DNA.

thymine dimer

What are somatic cells?

All cells of the body that are not germ-line cells.

Which of the following are causes of spontaneous mutations?

Errors made by DNA polymerase during replication Free radicals produced during metabolic processes that change nucleotide structure Insertion of a transposon into a gene

Which of the following are chemical mutagens?

Ethyl methanesulfonate Nitrous acid nitrogen mustard benzo(a)pyrene

This mutation in DNA is most likely caused by

UV light

Relatively small changes in DNA sequence are known as

gene mutations

Geneticists classify cells of animals into two types: __ -line cells and __ cells.

germ and somatic

Cells that give rise to gametes, such as egg and sperm cells, are known as the ____ - ____ cells

germ line

Gametes are produced by

germ line cells

Animal cells are classified into two main types. Which ones?

germ-line cells and somatic cells

X-rays and gamma rays are examples of ______ radiation, which is a type of electromagnetic radiation that can create free radicals.

ionizing

Mutations in noncoding sequences:

may affect gene expression

A heritable change in genetic material is known as a(n)

mutation

Mutations that do not alter the amino acid sequence of a polypeptide are known as ____ mutations

silent

What type of mutation has no effect on the amino acid sequence of a polypeptide?

silent

All cells of the body that are not part of the germ line are called _____ cells

somatic

Where must a mutation occur if it is to directly affect an amino acid sequence?

the coding region of a structural gene