Mutations Flashcards
What is a mutation
A change in the dna base sequence
How are mutations caused
Errors in dna replication
What is substitution mutation
One or more bases are swapped
What is a deletion mutation
One or more bases are removed
What’s an addition mutation
One or more bases are added
What’s a Duplication mutation
One or more bases are repeated
What’s an inversion mutation
A sew quince of bases are reversed
What’s a translocation mutation
Sequence of bases is moved from one location in the genome to another
Within the same chromosome or to a different one
Why can a mutation change the function of a polypeptide
Change in dna base sequence
Changes the amino acid base sequence it’s coded for
Changes primary and tertiary structure of polypeptide
Why is a mutation in an enzyme polypeptide bad
Change shape of tertiary structure
Change AS
Substrates can’t bind
Enzyme can’t catalyse the reaction
How can mutations cause genetic disorders
Caused by abnormal genes or chromosomes
Eg. In crease chance of developing some cancers or cystic fibrosis
What are hereditary mutations
If a gamete containing a mutation for a genetic distordre is fertilised. The fetus will express the mutated genes
When are mutations beneficial
Evolution by natural selection
If a mutation doesn’t cause a change in the amino acid sequence what is it called
A silent mutation
What does degenerate mean
More than 1 triplet of bases codes for the same amino acid
Why do addition/duplication/deletion mutation always cause a change in the amino acid sequence
They change the number of bases in the dna code
Causing a frame shift in the base triplets that follow
So that triplets are read in a different way to normal
Coding for different amino acids p
What are the triplets called that follow a mutation
Downstream of the mutation
How do mutagenic agents increase the rate of mutations
- Acting as a base
- altering bases
- Change structure of dna
How does “acting as a base” cause a mutation
Chemicals = base analogs
Substitute for a base during dna replication
Changing the base sequence of the base sequence
How can “altering bases” cause a mutation
Some chemicals can delete or change bases
How can changing the dna structure cause a mutation
Radiation changes the structure of dna
Causing problems in dna replication
How does 5-bromouracil affect dna
Acts as base Is a base analog Substitutes for thymine pairs with guanine Instead of adenine Causing a substitution mutation
How do alkylating agents affect dna
Add alkyl groups to guanine
Changes the structure
So it pairs with thymine and not cytosine
What mutagenic agent changes the structure of dna and how
UV radiation
Causes adjacent thymine bases to pair together
