Topic 8 Origins Of Genetic Variation Flashcards
what are three genetic reasons for genetic variation?
- mutations
- random independent assortment
- random fertilisation
- crossing over in meiosis
what are two types of mutations?
- point mutation (change in bases)
- chromosome mutation
what are 3 types of point mutations?
- deletion
- insertion
- substitution
why do point mutations happen?
- random
- mutagens increase rate of mutations (eg chemicals, radiation)
who is affected by somatic cell mutations?
only the individual
who is affected by gamete mutations?
generations to come, passed onto offspring
when does independent assortment happen during meiosis?
metaphase I and II
when does crossing over happen during meiosis?
prophase I
what are two types of chromosome mutations?
- translocation
- non disjunction
what is translocation mutation?
when a chromosome breaks off and joins a non-homologous chromosome
what is non-disjunction mutation?
when a homologous pair fail to separate correctly, some gametes have abnormal number of chromosomes
what are two types of non-disjunction?
monosomy and polysomy
what is an example syndrome of monosomy?
Turner’s syndrome
what is an example syndrome of polysomy?
Down’s syndrome
what is the chi squared equation?
(O-E)^2
———– (divide by)
2