Meiosis Flashcards
two advantages of asexual reproduction?
quick reproduction
tried and tested/works well
a disadvantage of asexual reproduction?
no variation to adapt to change
how many chromosomes do somatic human cells have?
46
what is a somatic cell?
any cell other than reproductive cells
what is diploid?
two sets of homolgous chromosomes
what is haploid?
one set of chromosomes
how many chromosomes do gametes have?
23
in fertilisation what provides varitation?
random chromosomes
what is meiosis?
duplication followed by cell division, two divsions so different to mitosis
explain meiosis 1?
homologous chromosomes line up on equator
cross over occurs
pulled apart by spindle fibres irrespective to mat pat origins
cell divides
explain meiosis 2?
chromosomes line up and chromatids pulled apart cytokinesis
what is cross over?
chiasmata formation
ties homologous chromosomes together
leads to recombination
what is synaptonemel?
protein that keeps homologous chromosomes together like glue
what is independant assortment?
when chromosomes pulled apart irrespective to maternal/paternal origins
3 things that happen when meiosis goes wring?
defects lead to sterility
defects can alter chromosome number (nondisjunction of spindle fibres)
alteration in chromosome number can cause genetic disease
