Mutations Flashcards
1
Q
What is a gene mutation
A
A change to one or more nucleotide bases causing a change in the DNA base sequence. This results in a new allele and occurs randomly
2
Q
What are the different types of mutation?
A
- Substitution
- Deletion
- Addition
- Translocation
- inversion
- Duplication
3
Q
Describe what occurs during subsititution
A
- A nucleotide base is changed for a different nucleotide base, affecting the DNA base sequence and changing the codon (affecting its primary structure)
- This means a different amino acid will be produce, disrupting a polypeptide chain
- This results in the protein having different properties and functions
4
Q
Describe what occurs during deletion
A
- A single nucleotide base is removed, this is a frameshift and it is shifted one to the left
- this means every codon from the site of deletion is changed, significantly affecting the amino acids produced
5
Q
Describe what occurs during addition
A
An extra base is added into the base sequence
- this results in a frameshift of one to the right
6
Q
Describe what occurs during duplication.
A
One or more bases are repeated more than once, this is a frameshift to the right
7
Q
Describe what occurs during inversion.
A
- A group of bases is separated from the base sequence and rejoins in the same position but is reversed.
8
Q
Describe what occurs during translocation
A
- A group of bases is separated from the base sequence and rejoins in a different chromosome.
- This leads to serious phenotype changes
9
Q
What are the causes of mutations?
A
- Mutagenic agents which include chemicals or highly ionising energy.
For example: - Uv light and x rays
- Chemicals such as nitrogen dioxide and tar in cigarettes
10
Q
What is the nature of mutations?
A
They are random.
11
Q
What are the benefits of mutations?
A
- it introduces new alleles into the gene pool, increasing genetic diversity
- This allows processes such as natural selection and speciation
