Lecture 27/Sea Urchin Dev

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e. Acrosome
The sperm is basically a stripped-down vehicle for transporting genes. It contains a haploid set of chromosomeswhich have been ultracompacted by the addition of a set of DNA-binging proteins, a flagellato supply motility and mitochondriato provide energy. The basal bodyof the flagella in sea urchin sperm, but not mammalian sperm, forms one of the asters for cell division. Finally, the sperm contain a very large exocytic vesicle known as the acrosomeat the very front, just under the plasma membrane.

2. Egg
a. Jelly coat
b. Vitelline membrane
c. Nucleus - haploid set of chromosomes
d. Yolk - concentrated at vegetal pole
e. Maternal mRNA
f. Cortical granules

Image #1

The sea urchin egg is 10,000 times bigger than the sperm. It is covered with the jelly coatand the vitelline "membrane", a protein "shell" just outside the plasma membrane. The vitelline membranecontains proteins that bind to sperm of the same species.

Because the egg must supply all of the needs of the embryo until it has developed a mouth and digestive system, it is jammed full of yolkgranules, mitochondria, metabolic precursors, endoplasmic reticulum and protein synthetic machinery. In addition to the nucleus, the sea urchin egg also contains 25-50,000 maternal mRNAspecies that control early development.

Finally, the egg contains a set of secretory vesicles, the cortical granules, lined up just inside the plasma membrane.

C. Sperm meets egg47.2, #2
1. "Egg receptors" in sperm plasma membrane bind
2. Signal transduction/ Ca++ influx
3. Acrosome reaction
a. Fusion of acrosomal and plasma membrane
b. Release of hydrolytic enzymes
c. Exposure of new membrane proteins


e. Acrosome The sperm is basically a stripped-down vehicle for transporting genes. It contains a haploid set of chromosomeswhich have been ultracompacted by the addition of a set of DNA-binging proteins, a flagellato supply motility and mitochondriato provide energy. The basal bodyof the flagella in sea urchin sperm, but not mammalian sperm, forms one of the asters for cell division. Finally, the sperm contain a very large exocytic vesicle known as the acrosomeat the very front, just under the plasma membrane.
		2. Egg a. Jelly coat b. Vitelline membrane c. Nucleus - haploid set of chromosomes d. Yolk - concentrated at vegetal pole e. Maternal mRNA f. Cortical granules	Image #1
The sea urchin egg is 10,000 times bigger than the sperm. It is covered with the jelly coatand the vitelline "membrane", a protein "shell" just outside the plasma membrane. The vitelline membranecontains proteins that bind to sperm of the same species. Because the egg must supply all of the needs of the embryo until it has developed a mouth and digestive system, it is jammed full of yolkgranules, mitochondria, metabolic precursors, endoplasmic reticulum and protein synthetic machinery. In addition to the nucleus, the sea urchin egg also contains 25-50,000 maternal mRNAspecies that control early development. Finally, the egg contains a set of secretory vesicles, the cortical granules, lined up just inside the plasma membrane.
	C. Sperm meets egg47.2, #2 1. "Egg receptors" in sperm plasma membrane bind 2. Signal transduction/ Ca++ influx 3. Acrosome reaction a. Fusion of acrosomal and plasma membrane b. Release of hydrolytic enzymes c. Exposure of new membrane proteins