4.3 Genetic diversity Flashcards
What does meiosis produce?
Haploid gametes - genetically different
Where does meiosis take place?
Sex organs
Why is it important that gametes are haploid?
So they can fuse together during fertilisation forming a diploid zygote
What is a chiasmata?
The point where the chromosomes join during crossing over
What is the full sequence of meiosis?
Interphase
Meiosis 1
Cytokinesis 1
Meiosis 2
Cytokinesis 2
What happens to the chromosomes during meiosis?
The no. Of chromosomes in each cell produced is decreased by half
What happens during meiosis 1?
Separation of bivalents
Produces 2 haploid daughter cells
What happens during meiosis 2?
Separation of sister chromatids
Produces 4 haploid daughter cells
What happens during prophase 1 in meiosis 1?
The chromosomes condense and become visible arranged as bivalents
The nuclear membrane breaks down
Spindle fibres same as mitosis
What happens during metaphase 1 of meiosis 1?
The bivalents align at the equator of the spindle apparatus
What happens during anaphase 1 of meiosis 1?
Spindle fibres shorten
Bivalents move to opposite poles - chiasmata break
What happens during prophase 2 of meiosis 2?
Chromosomes condense and become visible again
Nuclear membrane breaks down
Spindle fibres develop
What happens during metaphase 2 of meiosis 2?
The chromosomes are aligned on the equator or the spindle apparatus
How do the chromosomes align on the equator differently in meiosis 2 to meiosis 1?
The chromosomes align at right angles during meiosis 2 to the way they were aligned in meiosis 1
What happens in anaphase 2 in meiosis 2?
The centromere of each chromosome divides and the sister chromatids are separated
Spindle fibres shorten