Chapter 19: Gene Mutation anf DNA Repair

________ is a heritable change in the genetic mutation

Muations

What are the 3 types of muations?

Chromosome mutations

Genome mutations

Gene mutations

What is a Gene Mutation?

A relatively small change in the DNA structure that affects a single gene.

aka point mutation

What is a point mutation?

Change in single base pair

• base substitution

What are two examples of point mutations?

Transition

Transversion

Describe a transition point mutation

pyrimidine to another pyrimidine or a purine to another purine

Describe a transversion point mutation

pyrimidine to a purine or vice versa

• this type of point mutation can be more devestaiting due to its bigger change in geometry

What are Indels?

A type of point mutation and involves insertions and deletions of no more than 6 bases

List the 4 coding sequence mutations

Silent mutations

Missense muations

Nonsense mutations

Frameshift muations

What is a silent muations?

A mutation that does not alter the amino acid seq.

What is a missense mutation?

A base change that leads to an amino acid change

Has no detectable effect on protein function- neutral

• SINGLE AMINO ACID CHANGE

What is a nonsense muation?

A base substitution that changes to a termination (stop) codon

What is a frameshift mutation?

Addition or Deletions of nucleotides

• shifts the reading frame

Where would you find non-coding mutations? and what do they change?

Found in the promoter and regulatory regions

These mutations can change levels of gene expression (affect transcription)

• Up mutations increase expression (may increase transcription)

• Down mutations decrease expression (may decrease transcription)

_____-_____ is a relatively prevalent genotype

Wild-type

• (non-mutated, control, norm., most common)

A _______ mutation changes the wild-type genotype into some new variation

Forward

A _________ mutation changes a mutant allele back to the wild-type

Reverse

___________ mutations decrease the chances of survival

Deleterious

• they decrease fitness

__________ mutations enhance the survival or reproductive sucess of an organism

Benefical mutations

• increase biological fitness

___________ mutants affect the phenotype only under a defined set of conditions

Conditional mutants

• ex- temp sensitive

What is a Suppressor Mutation?

Two mutations that occur at different locations

• The second mutation affects the phenotype of the first mutation

• 2 mutations cancel each other out

Describe the difference between intragenic and intergenic muations in the second sit mutation of a suppressor mutation

INTRAgenic- 2 mutations in the same enzyme

• Mutation 1 disrupts protein function; Mutation 2 happens in same enzyme and restores protein function

INTERgenic- 2 mutations in different enzymes

• Mutation 1 inhibits protein function; Mutation 2 changes another protein/enzyme to preform that function

What are the 4 common ways INTERgenic suppressor mutations occur and describe them

Redundant function

Common pathway

Multimeric protein

Transcription Factor