Mutations Flashcards
What is a mutation?
A change to the base (nucleotide) sequence of DNA
What is a genome?
Entire set of genes/genetic material present in a cell/organism
What is a proteome?
Entire complement of proteins that can be expressed from those genes
Describe features of a mutation
- natural
- random
- happens continuously (always happening)
What are mutations caused by?
Errors during DNA replication
What can increase the likelihood of mutations?
Physical and chemical factors that affect DNA
Mutagenic agents
Give examples of mutagenic agents
Exposure to ionising radiation
Exposure to carcinogenic chemicals
What is a substitution mutation?
When one or more bases are swapped for another.
E.g. ATGCCT becomes ATTCCT
What is a deletion mutation?
When one or more bases are removed
E.g. ATGCCT becomes ATCCT
What is an insertion/addition mutation?
When one or more bases are added.
E.g. ATGCCT becomes ATGACCT
What is a duplication mutation?
When one or more bases are repeated
E.g. ATGCCT becomes ATGCCCCT
What is an inversion mutation?
When a sequence of bases is reversed.
E.g. ATGCCT becomes ACCGTT
What is a translocation mutation?
When a sequence of bases is moved from one location in the genome to another. This could be movement within the same chromosome or movement to a different chromosome.
What happens if a mutation occurs in a gene?
The sequence of amino acids in the polypeptide that it codes for could be changed
What may happen as a result of a change in the base sequence?
The primary structure of a protein may change. This will have a knock on effect on the secondary and tertiary structure of the protein?
What happens if mutation occurs in a protein that is an enzyme?
It would cause the active site of the enzyme to change shape meaning it could no longer form enzyme substrate complexes.
Why don’t all mutations affect the order of amino acids?
The genetic code is degenerate which means that some amino acids are coded for by more than one DNA triplet.
This means not all types of mutations will result in a change to the amino acid sequence of the polypeptide
What types of mutations do not affect the order of amino acids?
Substitutions
Inversions
What is the name given to the type of mutation that doesn’t cause a change in the amino acid order?
Silent mutation
What types of mutations do cause a change in the amino acid order?
Additions
Duplications
Deletions
What is the name given to the type of mutation that does cause a change in the amino acid order?
Frameshift mutation
Why do frameshift mutations occur?
Some mutations change the number of bases in the DNA code.
This causes a shift in the base triplets that follow so that the triplet codon is read in a different way.
What three ways can mutagenic agents increase the rate of mutations?
Acting as a base
Altering bases
Changing the structure of DNA
How can mutagenic agents acting as a base increase the rate of mutations?
Chemicals called base analogs can substitute for a base during DNA replication, changing the base sequence in the new DNA.
How can mutagenic agents altering bases increase the rate of mutations?
Some chemicals can delete or alter bases, so that bases pair with a different base.
How can mutagenic agents changing the structure of DNA increase the rate of mutations?
Some types of radiation can change the structure of DNA which causes problems during DNA replication
