Sources Of Variation Flashcards
1
Q
Variation
A
- existing genetic variation in an individual can be rearrange into different combinations by random assortment and crossing over (recombination) during meiosis when gametes are formed.
- Further variation arises due to the random fertilisation of gametes during sexual reproduction
- The environment can also affect the expression of genes and resulting phenotype
2
Q
Mutations
A
- New genetic variation arises from changes in the DNA of a cell called mutations.
- They can be beneficial, harmful or neutral.
& - Mutations can occur spontaneously or induced
3
Q
DNA
A
- DNA is a double-stranded molecule made up of a sequence of pairs of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). This code is read in sets of three pairs called codons which code for specific amino acids.
4
Q
Point/substitution
A
One base pair is swapped for another
5
Q
Silent
A
The change occurs in non-coding regions of DNA so it doesn’t affect the phenotype
6
Q
Missense
A
The codon now codes for a different amino acid
7
Q
Nonsense
A
The change codes for a stop codon, resulting in an incomplete protein
8
Q
Insertion
A
Extra base pairs are inserted into the DNA sequence
9
Q
Deletion
A
Base pairs are lost from the DNA
10
Q
Duplication
A
A section of the DNA is repeated
11
Q
Translocation
A
Sections of DNA either swap places or chromosomes join together