What are the three components of DNA? Which of these can be damaged?
Bases (bonded with weak hydrogen bonds)
Sugar ring (in the backbone)
Phosphate group (in the backbone)
They can all be damaged.
What makes up a nucleotide?
DNA bases and the sugar-phosphate backbone
Define 'DNA mutation'
A change in DNA sequence or rearrangement of genetic material
What are the two reasons why a person has a DNA mutation?
- Through parental germline, so passed on to offspring
- e.g. people who have been exposed to radiation can pass mutations to offspring who were never exposed
- Somatic cells
- Can accumulate and become malignant
What are the two main types of DNA mutation? Define them.
Micromutations – a change in the DNA sequence
Macromutations – rearrangements of genetic material
What are the three types of micromutation?
What are the five types of macromutation?
What are the five types of DNA mutation?
- Gross change
What effects can a mutation in the non-coding region of DNA have?
- Change product amount
- Change product activity
- No effect
Describe a silent mutation
A change in the base does not lead to a change in the amino acid sequence or protein due to the degenerate nature of DNA
Define 'missense mutation'
A mutation that changes an amino acid to another amino acid
Define 'nonsense mutation'
A mutation that causes a premature stop codon
What is a frameshift mutation?
A mutation that results in the loss or gain of multiples of amino acids other than three (e.g. 1, 2, 4, 5, 7)
What are four unnatural causes of DNA mutation?
- Ionising radiations/particles
- Free radicals
- Mutagenic agents
- Anti-cancer agents
What is the mechasnism of mutagenesis for unnatural causes of DNA damage such as ionising radiations?
DNA damage → defective or no DNA repair → mutation
What spontaneous events can lead to mutation?
- DNA replication errors
- Movement of transposable elements
What is the mechanism of mutagenesis for spontaneous events causing DNA damage?
Spontaneous events → mutation
How might mutations in parents' DNA affect their children?
Mutations in the germline will be inherited and may change the phenotype or predisposition in offspring
What happens if there's a mutation in a somatic cell?
There may be a change in the cell phenotype or disease predisposition in the individual