protein trafficking

• In the nucleas the  transcription  of DNA into mRNA happens.
• the mRNA then leaves the nucleas via the nuclear envolope.
• the protien made on ribosomes then enter the Rer.
• protien moves through the er assumng 3d shape en route.
• Vesicles pinched off the Rer contain the protien
• theese vesicles then move and fuse to the flattened sacs of the golgi appuratus.
• the proteins are modified and packed @ golgi 
• vesicles pinch off the golgi contain the modified protein
• the vesicle fuses with the cell surface membrane releasing protein such as exrtacellular enzymes via endocytosis

Key words:

transcription, Mrna leaves, Rer, through er, vesicles, fuse golgi apuratus, mod & pakced, fuse with the C.S.M.

• Day 14 egg released from the follicle in the ovary (ovulation)
• egg travels along the fallopian tube 
• sperm approches the egg in the fallopian tube
• chemicals from the follicle cells trigger acrosome reaction.
• acrosome swells fusing sperm to cell membrane of the egg
• hydrolitic/acrosome enzymes are released and hydrolise the follicle cells and zona pellucida.
• sperms fuses with the egg cell membrane.
• sperm enters the egg. The tail doesnt enter.
• cortical granuales and cause the zona pellucida to thicken/ harden = cortical reaction, preventing polyspermy.
• nuclei of the egg/ovum and sperm fuse, called zygotes.
• fetrilisation has now occured.