Biol 305 - Mutations And Dna Repair

Front 1

silent mutation

Back 1

-Change in nucleotide has no effect
-Usually mutation is in 3rd nucleotide in the codon

Front 2

missense mutation

Back 2

-Change in nucleotide alters the amino acid
-May have strong effect or little effect

Front 3

Conservative substitution

Back 3

Subtype of a missense mutation.
Change to an amino acid with chemical
properties(r-groups) similar to original amino acid. Doesn't affect protein conformation.

Front 4

Non-conservative substitution

Back 4

Subtype of a missense mutation.
Change to an amino acid with chemical
properties differing from original amino acid. More likely to affect protein conformation.

Front 5

Transition

Back 5

Missense -- Conservative/Non-Conservative
purine to a purine
pyrimidine to a pyrimidine

Front 6

Transversion

Back 6

Missense -- Conservative/Non-Conservative
purine to a pyrimidine
pyrimidine to a purine

Front 7

Nonsense mutation

Back 7

-Change an amino acid-specifying codon to a stop codon.
Effect? Truncated protein?

Front 8

Frameshift mutation

Back 8

-A nucleotide insertion or deletion causes shift in reading frame.
-Codons are 3’ to indel (insertion or deletion)
-Changes all amino acids after the mutation.
-Most frequent type of mutation.

Front 9

Expanding Trinucleotide Repeats

Back 9

-Mutations in which copies of 3 nucleotide repeats increase
greatly in number. Chromosomes more likely to break.

Front 10

Wild-type

Back 10

Any allele existing at a frequency of >1% in a
normal population….
OR
The most common phenotype in a population.

Front 11

Forward Mutation

Back 11

Any mutation that changes a wild-type
allele to a different allele. a+ to A or B+ to b (more common)

Front 12

Reverse Mutation

Back 12

Any mutation that causes a novel mutant
allele to revert to the wild-type allele.
A to a+ or b to B+

Front 13

Loss-of-Function Mutation

Back 13

This mutation reduces or abolishes protein activity. (most are recessive alleles)

Front 14

Null mutation

Back 14

These mutations completely block protein function.
Ex: Deletion of an entire gene

Front 15

Hypomorphic mutation

Back 15

Mutant produces lower levels of protein
than the wild-type. Protein has weak but detectable function

Front 16

Haploinsufficiency

Back 16

Subtype of hypomorphic mutations.
Heterozygote shows abnormal phenotype
because gene activity is too low to produce the normal phenotype.

Front 17

Dominant Negative Alleles

Back 17

Subtype of hypomorphic mutations.
Protein from mutant allele blocks activity of product from wild-type allele, causing loss of function in heterozygotes.

Front 18

Gain-of-Function Mutation

Back 18

Mutations that enhance a protein’s
function or confer new activity…Rare.

Front 19

Hypermorphic mutation

Back 19

Mutation in which more protein is formed than
normal or protein made is more efficient.

Front 20

Neomorphic mutation

Back 20

Mutation in which protein expressed in new time or place.

Front 21

Mutation Rate

Back 21

Frequency at which a gene changes from
the wild type to a mutant form.

# mutations/ gamete
# mutations/ cell division
# mutations/ round of replication
Influenced by:
-Frequency of primary changes in DNA
-Probability that DNA will be repaired
-Likelihood that mutation is detected

Front 22

Spontaneous Mutation

Back 22

A mutation in which errors that arise from natural changes in the DNA sequence.

Front 23

Induced Mutation

Back 23

A mutation caused by environmental factors like
chemicals or radiation.

Front 24

Unequal Crossing Over

Back 24

Homologous chromosomes mispair during
recombination.

Front 25

Depurination

Back 25

Loss of a purine

Front 26

Deamination

Back 26

Loss of amino group from base. Can be induced by nitrous acid.

Front 27

Chemical Mutagen

Back 27

A type of mutagen; Base Analogs
Structure of chemical similar to a base.

Front 28

Intercalating agent

Back 28

Distorts DNA.
Causes insertions or deletions during replication

Front 29

Direct DNA Repair

Back 29

Do not replace altered nucleotides, but instead
repair the damaged nucleotide.