Mutation and Genetic Variation Flashcards
1
Q
Mutation
A
- any heritable change in genetic material
- random mutations occur in replication, transcription, translation
- mistakes in nucleotide sequences are passed to daughter cells
- RNA is not inheritable, one mistake is not a big deal
2
Q
Somatic Mutation - japanese morning glory
A
- the mutation affects the ability to make purple/pink pigment
- a mutation occurred in the flower color gene in one cell
- descendants carry the mutation
3
Q
Somatic Mutation - Cancer
A
- mutation that increases the risk of disease is called a genetic risk factor
- colon cancer can be caused by a mutation of the Ras gene, derived by a mutation of the APC gene, or in the p53
4
Q
Genotype
A
- the genetic makeup of a cell or organism, the particular combination of the alleles present in an indiviudal
5
Q
Polymorphism
A
- any genetic difference among individuals that is present in multiple people in the population
6
Q
Allele
A
- A gene variant corresponding to a particular DNA sequence
7
Q
Homozygous
A
- individual inherits an allele of the same type from each parent (HH or hh)
8
Q
Heterozygous
A
- an individual who inherits different types of alleles (Hh)
9
Q
Phenotype
A
the expressed physical, behavioral and biochemical traits of an individual
10
Q
Polymorphism and HIV
A
- HIV enters the cell by interaction with receptors CD4 and CCR5 or CXCR4
- polymorphism in CCR5 has 32 base pairs (delta 32), prevents binding of the virus
- people HIV positive and homozygous for delta 32 rarely progress to AIDS
11
Q
Effects of Polymorphisms and Alleles
A
- polymorphisms can be harmful, beneficial or have a neutral effect on the phenotype
- changes in the third position have no affect (A-allele), in the second position may change the AA (S-allele), first position has a definite change in the AA (C-allele)
12
Q
Sickle-Cell Anemia and SNPs
A
- Sickle cell anemia is single nucleotide polymorphism which may be harmful
- SNPs are from a change in only one AA
- homozygous individuals will have all sickle cells, heterozygous will only have some
- heterozygous people tend to be resistant to malaria
13
Q
Small-Scale Mutations
A
Nucleotide substitution/point mutations:
- Synonymous (silent) mutations: does not change the AA
- Nonsynonymous (missense) mutations: changes the AA
- Nonsense Mutations: generates a STOP codon by mistake, effects size
Frameshift Mutations
14
Q
Large-Scale/Chromosomal Mutations
A
- Insertion
- Deletion
15
Q
Point Mutations
A
- Transitions: A to G, C to T
- Transversions: A to C or T, G to C or T
16
Q
Insertions and Deletions
A
- little effect in non-coding DNA, effect dependent on size is protein coding regions
- exact multiples of 3 lead to the deletion or addition of a codon (and an AA)
17
Q
Cystic Fibrosis
A
- caused by a faulty protein (CFTR) as a result of a deletion of 3 nucleotides that code for the PHE AA
18
Q
Frame Shift Mutations
A
- single base insertion that shifts the reading frame
- AA sequence is very different from the non-mutant
19
Q
Types of SNPs
A
- Linked: occur outside the gene, no impact on protein
- Non-coding: regulatory region of the gene, may affect the amount of protein
- coding: occurs in coding region, alters protein function by changing AA sequence
- Silent coding: occurs in the coding region but does not alter the AA sequence or function
20
Q
Transposable Elements
A
- DNA sequences that can move from one position to another in the genome
- can insert into a gene and change its function
- discovered by McClintock
21
Q
Copy Number Variation and Tandem Repeats
A
- Involve one or more gene, result in tandem repeats of the same gene
- Tandem Repeats are the number of alleles that repeats
22
Q
Gene Duplication and Divergence
A
- process of creating new genes from duplicates of old ones
- when a gene is duplicated, a copy is free to change without impacting the function of the old gene
23
Q
Chromosomal Level Insertions and Deletions
A
- insertion: region duplicated and present multiple times, less harmful
- deletion: region missing due to a replication error, more harmful
24
Q
Inversion
A
- genetic material flips and changes orientation
- paracentric: away from centromere
- pericentric: at centromere
25
Q
How do Mutations Occur
A
- Spontaneous, caused by mutagens
- X-rays
- UV light
- chemicals, bleach, hydrogen peroxide
- tobacco smoke
26
Q
DNA damage and repair
A
- one or more damaged bases signal a repair
- enzymes cleave the DNA backbone at sites flanking the damage
- gap is filed by new DNA syntheses
