D2.1 Meiosis Flashcards
How many chromosomes will have the product of meiosis?
23 chromosomes
How gametes are produced and why?
by meiosis, because this ensures that gametes have 23 chromosomes (n) zygote (2n) will have 46
How many divisions are in meiosis?
2
State the difference between anaphase I and anaphase II (it is about what is separated)
in anaphase I, the homologous PAIRS of chromosomes are separated and in anaphase II, the chromatids are separated
What is nondisjunction?
when chromosomes fail to separate correctly resulting in gametes with too many or not enough chromosomes
What Down syndrome is the result of?
trisomy 21 (3 copies of 21st chromosome)
When crossing over occurs?
Prophase I
What is bivalent?
it is a connected pair of two chromosomes (one from mum and one from dad)
What is synapsis?
formation of bivalent
What is chiasma?
a point where those chromosomes attach and crossing over occurs
What is crossing over?
exchange of alleles between non-sister chromatids of two chromosomes
When random orientation can occur?
metaphase I or II
What is random orientation?
it is the fact that when chromosomes align in the centre, they align randomly and not always the same way
