L3 Meiosis Flashcards
What cells are haploid
sperm and eggs
What does meiosis produce
sperm and egg cells
Diploid definition
organisms with two versions of each chromosome
What happens during the S phase of meiosis
DNA is replicated
How is genetic diversity created
recombination between homologous chromosomes
What does recombination depend on
proximity of chromosomes
When are sister chromatids separated in meiosis
anaphase II
What is the difference between mitosis and meiosis
meiosis produces haploid gametes, mitosis produces diploid cells
What is the function of the synaptoneal complex
facilitates DNA base pairing between homologues
What does the synaptoneal complex recognise
double stranded DNA breaks
How are homologues bound during recombination
cross linking by transverse filaments, axial cores and cohesin
How many crossing over sites occur per bivalent
1-4
What are the two types of chromosome abnormality
chromosome number and chromosome structural rearrangements
What is aneuploidy
Abnormal number of chromosome material in cells
Monosomy
one copy of a chromosome
trisomy
3 copies of a chromosome
Polyploidy
extra sets of chromosomes
Where does polyploidy apper
cell lines
Causes of aneuploidy
non-disjunction of chromosomes or sister chromatids
Non-disjunction
failure to separate
Non-disjunction in which phase of meiosis has more serious consequences
meiosis I
Are normal gametes produced if non-disjunction occurs in meiosis I
no
Nullsomy
missing pair of chromosomes
Embryonic lethal aneuploidy
monosomy, trisomy usually embryonic lethal
