2j- Meiosis Flashcards
What is meiosis?
The division of the nucleus that results in the formation of haploid gametes from a diploid gametocyte
In diploid cells, how do chromosomes typically appear?
As homologous pairs
What are homologous chromosomes?
Chromosomes of the same size, same centromere position and with the same sequence of genes at the same loci
What do the chromosomes, which have replicated prior to meiosis 1, consist of?
Two genetically identical chromatids attached at the centromere
Where do chiasmata form and what happens at them?
At points of contact between the non-sister chromatids of a homologous pair and sections of DNA are exchanged
What are linked genes?
Those on the same chromosome
What can crossing over result in?
New combinations of the alleles of these genes
What can be said about the crossing over of DNA?
It is random and produces genetically different recombinant chromosomes
What do spindle fibres attach to?
The homologous pairs and line them up at the equator of the spindle
What can be said about the orientation of the pairs of homologous chromosomes at the equator?
It is random
What is independent assortment?
Each pair of homologous chromosomes is positioned independently of the other pairs, irrespective of their maternal or paternal origin
What happens to the chromosomes of each homologous pair?
They are separated and move towards opposite poles
What happens after the chromosomes of each homologous pair are seperated and move towards opposite poles?
Cytokinesis occurs and two daughter cells form
What happens after meiosis 1?
Each of the two cells produced in meiosis 1 undergoes a further division during which the sister chromatids of each chromosome are separated
