meiosis Flashcards
interphase
homologous chromosomes duplicate (I like structures -> H like structures)
cell prepares for divison
difference between
- kinetochore
- centromere
- centriole
- centrosome
spindle fibres attach to centromere via kinetochore
-centrosome consists of 2 centrioles which the spinle fibre comes out of
describe meiosis 1
prophase: chiasmata; crossing over and recombination
metaphase: homologous chromosomes line up on cell equator
anaphase: homologous chromosomes split
telophase and cytokinesis
describe meiosis ii
prophase: no crossing over and recombination
metaphase: chromsoomes line up on cell equator
anaphase: sister chromatids split
telophase and cytokineses
overview?
interphase: single diploid I -> double dipolid H
meiosis 1: double diploid H goes to double haploid H
meiosis II: double haploid H goes to single haploid I
describe spermatogenesis
-sertoli cells: growth factors, signals and nutrients to aid differentiation
- germ cells
- spermatogonium
- primary spermatocyte
- > meiosis I
- secondary spermatocyte
- > meiosis II
- round spermatid
- spermatozoan
describe spermatozoan structure
- flagellum, midpiece, head
- axoneme, mitochondrial sheath, centriole, nucleous, acrosome, cell membrane
describe the follicle
oocyte surrounded by granulosa cells (homologous to sertoli)
describe oocyte structure
outside: zona pellucida (ECM)
cell
polar bodies between them
describe oogenesis
- germ cell
- oogonium
- primary oocyte
- > starts meiosis I arrested at P.I until FSH and then finishes meiosis I
- > follicle will burst forming corpus luteum which degenerates and releases hormones
- > polar body forms
- secondary oocyte
- > starts meiosis 2, arrested at M.I until sperm goes in
- > polar body forms
describe fertilisation
acrosomal reaction
cortical reaction (granules inactivate receptors)
sperm enters, egg’s meiosis II finishes, pronuclei fuse, boom you have a zygote with single nucleus.
define icsi
Single sperm injected directly into mature egg
