3.9 - Meiosis Flashcards
How does meiosis ensure genetic variation?
Crossing over
Independent assortement
What are the stages in meiosis?
Interphase
Prophase
Metaphase
Anaphase
Telophase
How does a parent cell prepare for meiosis?
DNA is replicated
Organelles are copied
Cell grows larger
What are homologous chromosomes?
The nucleus of the parent cell contains matching sets
of chromosomes - one maternal and one paternal.
What happens in prophase 1?
Chromosomes condense
nuclear envelope disintegrates
nucleolu disappears
spindle formation begins
homologous chromosomes pair up
forming bivalents
chromatids entangle
Where does crossing over happen?
Swapped between non-sister chromatids at chiasma
What happens in Metaphase 1?
Homologous pairs assemble along metaphase plate
each homologous undergoes independent assortemnt
maternal/paternal chromosomes end up facing either poles
results in genetic variation
What is independent assortement?
each homologous pair along the plate is rand and independent of any other homologous pair
What happens in anaphase 1?
homologous chromosomes are pulled to opposite poles by spindle fibres
chromatids stay attatched
chiasmata break = sister chromatids are no longer identical
What happens in telophase 1?
Chromosomes assemble at each pole and nuclear membranes reforms
chromosomes uncoil and undergoes cytokinesis
What is left by the end of telophase 1?
2 seperate daughter cells
What happens in mitosis 1?
pair of homologous chromosomes are seperated into cells
Haploid
