meiosis Flashcards
why do you need miosis
-for sexual reproduction
-makes sex cell
gametes
sex cell
2 human gametes
sperm (testes)
eggs (ovaries)
how is a offspring formed “formula”
sperm+eggs—-(fertilization)—–> zygotes
how many chromosomes come from each parent
23
is parents give so many chromosomes how many chromosomes does the offspring have
46
zygote
offspring
ploidy
number of sets of chromosomes
diploid
2n
2n
2 sets of chromosomes in humans
haploid
1n half a set
polyploid
anything more then 3
the zygote formula but with number of chromosomes
sperm + eggs = zygote
23 + 23 = 46
1n + 1n =2n
mitosis 2n to
2n
meiosis 2n to
1n
meiosis 1 is called
reproduction division
what happens in meiosis 1
homologous chromosomes separate and what the 2 cells have haploid cells with replicated chromosomes
haploid cell
a cell that contains a single set of chromosomes
meiosis 2
sister chromatids will separate and the 2 cells will have 4 different cells all together. you will end up with 4 1n haploid cells with unreplicated chromosomes
tetrad
4 chromatids
when chromatids cross over what can happen
a lot of genetic variations
and can do genetic “switches” sometimes
tetrad can be formed by what process
synapsis
independent orientation
When cells divide during meiosis, homologous chromosomes are randomly distributed to daughter cells, and different chromosomes segregate independently of each other.
3 types of chromosome and genetic variations
independent orientation
cross-over
random fertilization
