D1.3 Mutation and gene editing Flashcards
what is a gene mutation
a change in the sequence of bases of a particular gene
when can gene mutations occur
they are more likely to occur at certain times in the cell cycle than other times
such as when DNA polymerase fails to proofread errors during replication
what are factors that can change the sequence of bases in DNA
ionising radiation
UV
Chemicals
what is a point mutation
a change in one base in the gene sequence
can change the amino acid being coded by the gene
what is substitution mutation
change of one base to a different base copied by incorrect copying of DNAw
what is insertion mutation
additional base/s are added to the DNA
What is deletion mutation
removal of a base/s from DNA
what are frameshift mutations
mutations in DNA where the number of nucleotides removed or inserted arent in a multiple of 3, leading to every codon afterwards to be read incorrectly during translation
happens due to deletions/insertions
what are nonsense mutations
codes for a stop codon meaning the rest of the code isn’t read
what is missense mutation
results in a different amino acid being coded for
what is a sense mutation
when the mutation has no effect due to degeneracy of the genetic code
what happens if the substitution occurs in a non coding region
the mutation may have a neutral effect on the proteome of the cell
what are single nucleotide polymorphisms
they are the result of base substitution mutations
what is the result of mutations
they increase the likelihoods of polypeptides not functioning properly
what is an example of an insertion mutation
Huntingtons disease
Explain Huntington’s disease
Insertions can result in repeating base sequences of three nucleotides, which lead to abnormal number of triplet repeat sequences
In huntington’s there is an abnormality in the HTT gene
A DNA segment (CAG trinucleotide repeat) is repeated multiple times in a row (10-35)
mutation leads to a higher number of these causing degenerative effects
what is the result of Huntington’s disease
neurodegenerative disease
progressive mental deterioration
involuntary muscle movements
Explain the delta 32 mutation in relation to HIV
the delta 32 mutation is a deletion mutation which prevents the production of CCR5 protein which is a receptor. Without this receptor, HIV finds it harder to bind to the cell and enter
people who have two copies of the mutation are less susceptible to infection
what is a mutagen
a factor capable of causing a mutation
explain ionising radiation as a mutagen
X rays and radiation can damage ions inside the nucleus leading to breakup of DNA
explain non ionising radiation as a mutagen
UV light
less penetrating but if absorbed, can cause adjacent bases on DNA strand to bind to each other instead of opposite base
explain bacterial infection as a mutagen
specific bacterial infections can trigger cancers
explain chemicals as a mutagen
can be carcinogenic. prolonged exposure to chemicals can trigger cancer
explain virus infection as a mutagen
specific infections that may trigger DNA mutations
some can insert part of the virus genome into the host and produce proteins that alter the cell cycle
leads to uncontrolled replication of cells
