Gene Expression- Mutations Flashcards
What is a mutation?
Any change to the base sequence
How can mutations be caused?
By errors during DNA replication
How can the rate of mutation be increased?
By mutagenic agents
What are the types of mutations that can occur?
Substitution, deletion, addition, duplication, inversion and translocation
What is a substitution mutation?
One or more bases are swapped for another
What is a deletion mutation?
One or more bases are removed
What is an addition mutation?
One or more bases are added
What is a duplication mutation?
One or more bases are repeated
What is an inversion mutation?
A sequence of bases is reversed
What is a translocation mutation?
A sequence of bases is moved from one location in the genome to another- could be a movement within the same chromosome or movement to a different chromosome
Why is the order of DNA bases in a gene important?
Determines the sequence of amino acids in a particular polypeptide
What could happen if a mutation occurs?
The sequence of amino acids in the polypeptide that it codes for could be changed
What might a change in amino acid sequence of a polypeptide cause?
A change in tertiary structure of the protein which could mean it doesn’t work properly
What are genetic disorders?
Inherited disorders caused by abnormal genes or chromosomes
What can some mutations increase the likelihood of?
Developing certain cancers
What does the degenerate nature of the genetic code mean?
Not all types of mutation will always result in a change to the amino acid sequence of the polypeptide
Which mutations will almost always change the amino acid sequence of a polypeptide?
Additions, duplications and deletions because these mutations change the number of bases in the DNA code
What does changing the number of bases in the DNA code cause?
A shift (frameshift) in the base triplets that follow so the triplet code is read in a different way
What are some mutagenic agents?
Ultraviolet radiation, ionising radiation, chemicals and viruses
What are the three ways mutagenic agents can increase the rate of mutations?
- Acting as a base- chemicals called base analogs can substitute for a base during DNA replication, changing base sequence for new DNA
- Altering bases- some chemicals can delete or alter bases
- Changing structure of DNA- some types of radiation can change structure of DNA and cause problems in DNA replication
