inheritance and genetic diseases Flashcards
1
Q
How is genetic variation generated?
A
- mutation
- diploid cells (random fertilisation)
- homologous recombination between chromosomes during meiosis
2
Q
Describe homologous recombination
A
- occurs during long prophase of meiosis 1
- 2-3 crossover events per chromosome per meiosis
- highly similar DNA sequence binds to complementary sequence on homologous chromosome
3
Q
How does genetic variation happen during gamete formation?
A
- independent assortment of chromosomes
- homologous recombination
4
Q
What is non-disjunction?
A
When a pair of homologous chromosomes fail to seperate during meiosis
5
Q
What are the 3 types of survivable trisomy?
A
- 21 (down’s syndrome)
- 13 (patau’s syndrome)
- 18 (edwards syndrome)
6
Q
What are autosomal chromosomes?
A
not sex chromosomes
7
Q
How are genetic diseases passed down through the generatons?
A
- autosomal dominant
- autosomal recessive
- x-linked
- family history: genetic counselling
8
Q
Define genotype?
A
set of genes carried by an individual
9
Q
Define phenotype?
A
observable characteristic of an organism
10
Q
Define allele?
A
an alternative form/different version of a gene
11
Q
A
