LECTURE 11 Flashcards
(24 cards)
layers of sperm head from the outside in
plasma membrane, outer acrosomal membrane, acrosomal space containing enzymes, inner acrosomal membrane, nucleus
what is in the sperm neck?
centriole to form spindle in zygote
what is in the sperm midpiece
mitochondria to generate energy for tail movement
what does the sperm head contain?
large nucleus with 23 chromosomes (22 autosomes and 1 sex chromosome)
what is in the acrosome cap
enzymes to help penetrate ovum; has inner and outer membranes
during spermatogenesis, cells are connected by what? and why?
connected through cytoplasmic bridges because some x products are essential to spermatocyte development (that y chromosome doesnt have)
secondary oocyte is surrounded by what 3 layers?
- perivitelline space (between oocyte and zona pelucida
- zona pellucida: a matrix of 3 glycoproteins (zp 1, zp2, and zp3)
- comulus oophorus (corona radiata)
consists of 2-3 layers of follicular cells
purpose is to provide protection and vital proteins to cell
what is the journey of the ejaculated sperm?
vagina - cervix - uterus - oviduct - amullary isthmic junction (where fertilization takes place)
sperm moves in response to what taxes?
chemotaxis and thermotaxis
what do white blood cells do in uterine lumen?
eat up dead and dying sperm
what is sperm capacitation?
initially, sperm cannot move, however sperm capacitation involves
- modification or removal of glycoproteins on sperm mebrane that would othewise inhibit signals that activate acrosome reaction
- hyperactivation of sperm tail
how does cilia transport sperm and ovum?
cilia at ridges beat and move material towards uterus, cilia in grooves beat and move material towards ovary
how long can egg be fertilized for?
24-48 hours after ovulation
how long do sperm live up to?
3 or 4 days inside reproductive tract
how long does fertilization process take?
up to 24 hours
how does sperm pass through first protective layer?
- sperm passes through cumulus oophorus. hyaluronidase, an enzyme on sperm head, breaks down hyaluronic acid which is a glue that holds cells together
how is the acrosomal reaction initiated?
zp3 on egg binds a receptor on the sperm plasma membrane to trigger acrosome reaction.
what is the acrosomal reaction
in the acrosome reaction, sugars on zp3 are bound by galT. zp3 induces aggregation of GalT on the surface of the sperm. zp3 on egg surface induces aggregation of galt on the surface of the sperm head this causes a g protein cascade and excocytosis of acrosome
how is the zona pellucida degraded?
acrosomal enzymes degrade a hole in the zona pellucida and sperm moves through
how is nucleus and centriole released?
egg binding proteins on sperm cell surface bind to moelcues on the egg cell membrane and sperm cell membrane fuses with egg plasma membrane. nucleus and centriole enter egg cytopasm.
what happens when sperm enters egg?
causes rapid release of calcium which triggers fusion of cortical granules. fused cortical granules release contents into perivitelline space. which are thought to be enzymes that destroy receptor sites so sperm cannot fuse
what is egg activation
happens right after fertilization involves the completion of meiosis II, increase in egg metabolism, syntehsis of protein, dna, and rna, preparation for first mitoic devision
what is syngamy?
fusion of sperm and egg pronuclei to form a diploid cell.
general overview of fertilization
sperm plasma membrane fuses with outer acrosomal membrane, exocytosis of acrosomal contents which dissolve the zp, sperm and egg membrane interact and fuse
