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