Genetic variation Flashcards
What is the difference between mutations and genetic variation
Mutation
Represents changes in the base sequences that typically occur much less than 1% of the population
Genetic variation occurs through positive selection
What are the different types of mutations
Stand breakage base loss base changes dna crosslinkages Dna replication error
Define strand breakage
nucleotides lost before end joining
Define Base loss
glycosidic bond is broken or enzymatically cleaved
Define base change
Guanine is oxidises to 8- oxoguanine and then base pairs with adenine and cytosine loses an amine group and becomes uracil and base pairs with adenine.
Define crosslinkage
UV light causes cyclobutane dimers and anticancer ages
What occurs when DNA repair mechanism fails
Leads to genetic damage such as cancer, accerlated raging, neurological defect and immunodeficiency.
How does genetic variation occur
Recombinant DNA
what are the types of mutations
Point mutation
changes to a single nucleotide
- missene snd nonsense
insertions and delation.
Chromosonal mutations
- polyplody
- Aneuploidy
- Chromosome rearrangements
Define and describe a missense mutation
A change in nucleotides sequence that results in a change to the amino cid sequence
includes point mutations and frame shift
Describe a nonsense mutation
A change in the nucleotide sequence that results in a premature stop codon
results in a non functional protein
What type of disease can be caused by expanding trinucleotide repeats
Huntingtons disease
Fragile X syndrome
Kennedy Disease
Myotonic Dystrophy
What are transposons
They’re sequences in the DNA that can move around the genome
What is haploinsuffienceny
When one copy is deleted or inactivated by a mutation so you only have one copy functioning.
