Mutation Flashcards
rare alleles are termed
mutations
an organisms containing rare alleles are termed
mutants- often non functional proteins
the normal allele organism are termed
wild types- normal proteins
mechanisms of preventing mutation
-proofreading DNA polymerases -post replication mismatch repair- Muts and MutL -DNA repair by homologous recombination -cell cycle checkpoints
environmental factors which cause mutations
radiation chemical mutagens
replication slippages
can generate Short tandem repeats or minisattelites variation e.g. additions
![](https://s3.amazonaws.com/brainscape-prod/system/cm/203/830/855/a_image_thumb.png?1482858195)
variation in a single gene is
necessary and sufficient too cause disease - more than 1000 genes known in humans
mutations and mendelian disorders
mendelian disorders are controlled by a single locus in an inheritance pattern- therefore a mutation in a single gene can cause disease
example of a mutated single gene causing disease
cystic fibrosis-recessive sickle cell anaemia -recessive albinism -recessive Huntingtons- dominant Haemophilia A- x linked
in diploids mutations are normally..
recessive, this is why mutations are lethal in haploid or homozygous organisms
mutations and selections
Ledeerbergs experiment in 1952 showed that mutations occur before selection, therefore selection does not cause mutation
![](https://s3.amazonaws.com/brainscape-prod/system/cm/203/830/860/a_image_thumb.png?1482858394)
transition mutations
a point mutation that changes a purine nucleotide to another purine (A G) or a pyrimidine nucleotide to another pyrimidine ( T C)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/203/830/861/a_image_thumb.png?1482858212)
purine nucleotides
A G
pyrimidine nucleotides
C T
pyrimidine nucleotides
C T
Transversion mutation
substitution of a two ring purine for a one ring pyrimidine or vice versa e.g. A substituted for T e.g. G substituted for C