Meiosis Flashcards
What is the definition of meiosis?
The division of the nucleus that results in the formation of haploid gametes from a diploid gametocyte
In diploid cells what do chromosomes typically appear as?
Homologous pairs
What is the definition of homologous chromosomes?
homologous chromosomes are chromosomes of the same size, same centromere position, and with the same sequence of gene at the same loci (plural of locus)
What are the two stages of meiosis?
Meiosis I and meiosis II
What do the chromosomes, which have replicated prior to meiosis I consist of?
Each consist of two genetically identical chromatids attached to the centromere
What happens to the chromosomes at the beginning of meiosis I?
They condense and the homologous chromosomes pair up
Where do chiasmata form during meiosis I?
They form at points of contact between the non-sister chromatids of a homologous pair and sections of DNA are exchanged
During meiosis I what are called linked genes?
Those on the same chromosomes
During meiosis I what can the crossing over of DNA result in?
New combinations of the alleles of these genes
Is crossing over of DNA during meiosis I random?
Yes
What does the crossing over of DNA during meiosis I produce?
Genetically differing recombinant chromosomes
What do spindle fibres do during meiosis I?
They attach to the homologous pairs and line them up at the equator of the spindles
In meiosis I how is the orientation of the pairs of homologous chromosomes at the equator decided?
It is random
What is independent assortment?
In meiosis I when the pairs of the chromosomes are lined up on the equator, each pair of homologous chromosomes is positioned independently of the other pairs, irrespective of their maternal and paternal origin.
What happens after the pairs of chromosomes line up on the equator during meiosis I?
The chromosomes of each homologous pair are separated and move towards opposite poles. Then cytokenisis occurs and two daughter cells form
