Chapter 12

Steps involved in excision repair in the correct order.

1) repair enzymes bind to damaged DNA 2) repair enzymes excise the damaged DNA and some surrounding bases 3) DNA polymerase synthesizes the correct nucleotides 4) DNA ligase seals the sugar-phosphate backbone

Mutations that prevent collagen from assembling properly result in

Ehlers-Danlos syndrome

You have performed exome sequencing and have identified a gene in which two different mutant forms are prevalent. Each mutation is a missense mutation, but they are found in different parts of the gene. What can you conclude about these mutations?

They may each cause a different disease.

In _______________________, one to five nucleotides of a DNA strand are replaced.

base excision repair

Sickle-cell disease is caused by a mutation in the __________ globin polypeptide chain.

beta

The protein _________________ accounts for over 50% of the dry weight of skin.

collagen

DNA sequences that vary in number from one person to another are called

copy number variants

_______________________________ does not correct DNA damage but allows replication and transcription to proceed.

damage tolerance

A(n) ___________________________ removes bases from a DNA sequence.

deletion mutation

Spontaneous mutations occur most commonly as a result of

errors in DNA replication

A conditional mutation has the same effect on phenotype under all conditions. True/False

false

All mutations in the beta-globin gene reduce the affinity of the molecule for oxygen. True/False

false

All mutations within a given gene will affect the protein the same way. True/False

false

An insertion of two nucleotides into the coding sequence of a gene would result in a ____________________ mutation.

frameshift

A(n) _______________________________ is an insertion or deletion of DNA bases from a coding sequence in which the number of bases added or removed is NOT a multiple of three.

frameshift mutation

A mutation that occurs during the DNA replication preceding meiosis is called a

germline mutation

In sickle-cell anemia, ___________________ abnormally aggregates.

hemoglobin

A region where mutations occur more often than usual is called a

hot spot

A(n) _______________________________ adds bases to a DNA sequence.

insertion mutation

Newly replicated DNA is "proofread" by enzymes during

mismatch repair

A(n) _____________________ changes a codon for one amino acid into a codon for a different amino acid.

missense mutation

Mitochondrial genes have a higher spontaneous mutation rate than nuclear genes because

mitochondria cannot repair their DNA

An agent that causes mutations to occur is called a

mutagen

A _____________ is a change in a DNA sequence that is rare and typically affects the phenotype.

mutation

A(n) ____________________________ replaces a codon specifying an amino acid with a stop codon.

nonsense mutation

In _______________________, up to 30 nucleotides of a DNA strand may be replaced.

nucleotide excision repair

Both thalassemia and sickle-cell anemia result from problems in ____________ delivery.

oxygen

Fungi can repair damage to DNA caused by ultraviolet light in a process called

photoreactivation

A(n) ___________________ changes a single base in a DNA sequence.

point mutation

A ___________________ mutation will be present in some of the cells in an individual's body but will be absent from other cells.

somatic

A mutation that causes a patch of white hair on a person's head when the rest of his hair is brown is most likely a

somatic mutation

A mutation that occurs during the DNA replication preceding a mitotic cell division is called a

somatic mutation

A mutation that causes an exon to be skipped is a __________________________ mutation.

splice site

A(n) ________________________ occurs when a gene is duplicated and the two copies of the gene are next to each other.

tandem duplication

In ______________________, not enough hemoglobin is produced.

thalassemia

Ultraviolet light damages DNA by causing the formation of

thymine dimers

A(n) _______________________ is a mutation that replaces a purine with another purine or a pyrimidine with another pyrimidine.

transition

When a gene is disrupted by a DNA sequence "jumping" into it and disrupting the reading frame, the DNA sequence that jumps into the gene is called a

transposon

A(n) ______________________ is a mutation that replaces a purine with a pyrimidine or vice versa.

transversion

A mutation that changes the DNA sequence CCA to CCC, but does not change the amino acid encoded by the sequence, is a ___________________ mutation.

tranversion

A mutation in the third position of a codon is less likely to change the amino acid encoded than a mutation in the first or second position of the codon. True/False

true

Mutation is essential for evolution. True/False

true

The term _________________ is increasingly being used to mean both polymorphism and mutation.

variant