MUTATIONS Flashcards
1
Q
Mutation (3)
A
A change in the - amount - arrangement - structure of the heredity material of the organism
2
Q
Inheriting mutations
A
Can only inherit mutations in the gametes
3
Q
Mutations are… (2)
A
- Spontaneous - happen without apparent cause
- Random - happen with equal chance anywhere in the genome of diploid organisms.
4
Q
Mutation rates are increased by (2)
A
- Ionising radiation - radiation joins adjacent pyramidine bases together so at replication the nucleotide may be incorrect
- Mutagenic chemicals - slide in between the base pairs prevent DNA polymerase from inserting the correct nucleotide
5
Q
Ways mutations can occur (4)
A
- Gene/point mutation - not copied during s phase correctly - involve a small number of bases
- Chromosome mutation - chromosomes get damaged and break, may be repaired incorrectly affecting a large number of genes
- Aneuploidy - a whole csome may be lost or added if they fail to seperate at anaphase I or II
- polyploidy - number of chromosomes may double if cells fail to divide after fertilisation
6
Q
Types of gene/point mutation (6)
A
- Addition - a base is added, 3 times = a new amino acid
- Duplication - same base is incorporated twice
- Subtraction - a base is deleted, 3 times = lose an amino acid
- Substitution - a different base is added
- Inversion - adjacent bases exchange positions
7
Q
Potential outcomes of gene/point mut (3)
A
- silent mutation (different bases, same amino acid)
- small effect if a similar chemical is substituted
- may affect active site and cause significant difference to function
8
Q
Sickle-cell Anaemia (6)
A
- Substitution point mutation
- produces valine instead of glutamate
- glutamate is large and hydrophiliic while valine is small and hydrophobic
- when o2 tension is low affected cells aggregate
- cell membrane collapses producing sickle-shape
- affected cells are fragile and may break
9
Q
Types of chromosome mutations (2)
A
- Structure mutations
- Number mutations
10
Q
non-disjunction
A
chromosomes are not shared equally between daughter cells
11
Q
translocation downs
A
when extra chromosomes are attached to another
12
Q
euploid
A
cells with complete sets of chromosomes
13
Q
polyploid
A
several sets of chromosomes
14
Q
Causes of polyploidy
A
- defect in the spindle causing all chromosomes/chromatids to go to one side
- if two diploid gametes fuse
- endomitosis - replication of chromosomes without cytokinesis
15
Q
why is polyploidy more common in plants? (2)
A
- can reproduce asexually
- are hermaphrodite so do not determine sex by chromosomes
