mutations Flashcards
define mutation
change in the sequence of bases in DNA
define point mutation
when single base pair is altered by mutation
define substitution mutation
one base pair is replaced by a different base pair
define deletion
when one or more bases is removed from a sequence
define insertion
addition of one or more nucleotide base pairs into a DNA sequence
define frameshift
mutation caused by insertion/deletion in a DNA sequence - shifts the way the sequence is read
- changes every successive codon from point of mutation
define silent mutation
mutations in DNA that do not have an observable effect on organism’s phenotype
- result in same AA coded for / mutation occurs in non-coding DNA region
define nonsense mutation
substitution of a single base pair leading to appearance of stop codon
- results in shorted and likely non-functioning protein
define missense mutation
where single base pair substitution results in the incorporation of an incorrect AA in the primary structure
define gene mutation
affects single gene/section of DNA
define chromosome mutation
affects whole chromosome / number of chromosomes within a cell
explain why a change in sequence of nucleotides in a gene can affect the function of the protein produced
- causes a change in the codon(s)
- if new codon(s) codes for different aa = change in primary structure of protein
- position & involvement of aa in R group interactions within protein will change - final folding + structure will be different
describe how a change in the sequence of nucleotides can have a neutral effect.
- same protein may still be synthesised (degenerate)
- mutation occurs in non-coding DNA
- change doesn’t affect organism function
describe how a mutation can have a harmful effect
- proteins are no longer synthesised / non-functional
- can interfere with essential metabolic processes
describe how a mutation can have a beneficial effect
- protein synthesised results in new + useful characteristic in phenotype
what are 2 examples of beneficial mutations
- mutation in human CSM can lead to HIV not being able to bind + enter cells - immunity to HIV
- ability to digest lactose - present primarily in European populations who were more likely to farm cattle
state 3 types of mutagens
- physical
- chemical
- biological
give an example of a physical mutagen
ionizing radiation
give an example of a chemical mutagen
deaminating agents
give 3 examples of biological mutagens
- alkylating agents
- base analogs
- viruses
describe deletion as a chromosome mutation
section of chromosome breaks off and is lost within the cell
describe duplication as a chromosome mutation
sections of chromosome get duplicated
describe translocation as a chromosome mutation
section of one chromosome breaks off and joins another non-homologous chromosome
describe inversion as a chromosome mutation
section of chromosome breaks off, is reversed and rejoins chromosome
give an example of the effect a substitution chromosome mutation can cause
sickle cell anaemia
give an example of the effect an insertion chromosome mutation can have
Huntington’s disease
give an example of the effect an deletion chromosome mutation can have
cystic fibrosis