3B : Reproduction and Inheritance Flashcards
what is the cortical reaction
cortical granules move towards the membrane and release contents- forming a fertilisation membrane
what is the acrosomal reaction
when the acrosome releases digestive enzymes to allow the sperm to penetrate the egg cell membrane
how is the zone pellucida adapted to its function
after fertilisation, the membrane changed shape and thickens to prevent any more sperm from entering the cell
what is the process of fertilisation
- sperm swims towards egg cell located in the oviduct
- sperm makes contact with zona pellucida and acrosomal reaction occurs
- the ZP gets digested allowing the sperm cell to move through the cell membrane of the egg cell
- sperm cell fuses with egg cell membrane tiggering he cortical reaction
- ZP thickens making it impenetrable to other sperm cells
- nucleus of sperm cell fuses with nucleus of egg cell
where are genes loacted on chromosomes
on the locus
how can genetic variation be achieved through meiosis
crossing over on chromatids
independant assortment
what is the process of crossing over
- prior to meisos first division, homologous pirs of chromosomes pair up
- two chromatids of each pair twist around eachother
- twisted parts break off and join onto the other chromatid, combning their genetic material
- new combination of alleles has been made
what is the process of independent assortment
when the gametes are produced from meiosis, different combinations of parental chromosomes go to each cell
what is gene linkage
when 2 genes are very close to eachother on a locus and therefore are seen as linked and will stay together during IA
what is sex linkage
when the locus of an allele for a charcteristic is on a sex chromosome
- normally shown even if recessive bc there isnt another copy of the allele (males)
