D1.3 Mutations & gene editing Flashcards
(24 cards)
What is a mutation?
A change in a genetic composition of a cell
What is a gene mutation?
a change in the order of bases on a strand of DNA
How do mutations happen?
When a mistake is made when DNA is copied during the production of gametes
What are the 3 types of mutations?
Substitution
Insertion
Deletion
What are SNPs (single nucleotide polymorphisms)?
Base substitution mutation, most common type of genetic variation
When do SNPs occur?
When 1 nucleotide is replaced by another nucleotide in the DNA sequence
What is a synonymous substitution?
They do not change the amino acid sequence due to the degeneracy of the genetic code
What is a non synonymous substitution?
Change the amino acid sequence having different effects on protein function, possibly leading to protein malfunction
What are synonymous substitutions also known as?
Same-sense mutation
What are non-synonymous substitutions also known as?
Non-sense / mis-sense substitutions
What do frameshift mutations do?
Alters the amino acid sequence coded for by the DNA sequence
What is the genetic code read in?
Codons
What are codons?
A sequence of 3 consecutive nucleotides in DNA or RNA that code for a specific amino acid sequence OR signal start & stop of protein synthesis
What are causes of gene mutation?
- errors in DNA replication OR repair which may be triggered by mutagens
What are mutagens?
Chemical OR physical agents which have the ability to alter the genetic sequence
What are some examples of physical agent mutagens?
Radiation
- Ultraviolet
- ionising radiation (X rays)
- gamma rays
- radioactive isotopes
Which base has a higher probability of mutating? and why?
Cytosine, it can undergo deamination (loses an amine group, cytosine -> uracil)
What does somatic cells mean?
All body cells except germ cells
What does germ cells mean?
These cells give rise to the sperm & egg
What is the difference between the consequences of germ cells & somatic cells?
Somatic - does not get passed onto offspring
Germ - passed onto offspring (inherited)
What are the possible effects of changing the base sequence?
- same protein produced
- different but functioning protein is produced
- non-functioning protein is produced
- no protein produced
- improvement
What are some good effects of mutations?
- very occasionally give an organism better chance of survival
- help species adapt to an environment over time
What are the bad effects of mutations?
- can cause cells to multiply out of control (cancer)
- mutation in gamete -> foetus may die
What is a silent mutation?
have no effect, passed through generations
