Chapter 24 - Variation Flashcards
1
Q
What is variation?
A
The differences between individuals of a species
2
Q
What causes variation?
A
- mutations
- environment
- variation from meiosis: random assortment, crossing over, non disjunction
- variation from fertilisation: random fertilisation
3
Q
What is random assortment?
A
- during anaphase 1, each pair of chromosomes segregates independently of every other pair
- segregation is a random process
4
Q
What is crossing over?
A
- during prophase 1 matching regions on homologous chromosomes break and then reconnect to the other chromosome
- crossing over creates new combinations of genes
5
Q
What is non-disjunction?
A
- failure of chromosomes to separate correctly
- monosomy: a chromosome is missing
- partial monosomy: part of a chromosome is missing
- trisomy: extra copy of a chromosome
- partial trisomy: part of an extra chromosome is attracted to another
