Developmetal Biology

Front 1

What is the the basic structure of sperm modification of a germ cell to form a mature mammalian sperm?

Back 1

• 1. The centriole produces a long flagellum at what will be the posterior end of the sperm, 2. The Golgi apparatus forms the acrosomal vesicle ant the future anterior end, 3. The mitochondria collect around the flagellum near the base of the haploid nucleus and become incorporated into the midpiece or neck of the sperm, 4. The cytoplasm is jettisoned , and the nucleus condenses.

Front 2

What is in an axoneme?

Back 2

the core consists of two central microtubules surrounded by a row of nine doublet microtubules. The doublet microtubules consist of a complete doublet of 13 protofilaments and a C-shaped with 11 protofilaments. The protofilaments are connected by a protein called tubulin. Another protein called dynein is attached to microtubules, which makes energy to propel the sperm.

Front 3

What are the basci components of an axoneme?

Back 3

Cell membrane, radial spokes, nexin, microtubule doublet, central singlet microtubule, inner dyenin arm, and outer dyenin arm

Front 4

• Genetic syndrome in which individuals lack functional dynein in all their ciliated and flagellated cells , rendering these structures immotile. Men with this disease are sterile. Both men and women with this syndrome are susceptible to bronchial infections and have a fifty percent chance of having the heart on the right side of the body.

Back 4

Kartagener’s Triad

Front 5

• Jelly layer, vitelline envelope, cell membrane,sperm, cortical granules, mitochondria, and nucleus

Back 5

Basic Structure of a Sea Urchin and Mammalian Egg at Fertilization

Front 6

What are the sequence of events leading to the sperm egg fusion in a sea urchin?

Back 6

1. The sperm is chemotactically attracted to and activated by the egg, 2. Contact with the egg jelly triggers the acrosome reaction and in this process forms and releases proteolytic enzymes, 3. The sperm adheres to the vitteline envelope and lyses a hole in it, 4. The sperm pronucleus can now enter the egg cytoplasm

Front 7

What are the sequence of events leading to the sperm egg fusion in a mammal?

Back 7

1. The contents of the female reproductive system capacitate, attract, and activate the sperm, 2. The acrosome intact sperm binds to the zona pellucida, 3. The sperm digest the a hole in the zona pellucida , 4. The sperm adheres to the egg and there cell membranes fuse

Front 8

What is the role of chemotaxis in sperm/egg attraction and the proposed mechanism of how it works (molecular level, how resact works) ?

Back 8

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Front 9

What is bindin?

Back 9

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Front 10

What is meant by sperm capacitation?

Back 10

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Front 11

How does sprem capacitationit occur?

Back 11

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Front 12

How and where species-specific recognition is accomplished in sea urchins as well as gamete binding in mammals and involvement of the ZP1 through 3 molecules?

Back 12

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Front 13

What happens in the acrosome reaction?

Back 13

• Caused by a second interaction between sperm and egg jelly which causes exocytosisof the sperms acrosomal vesicle and proteolytic enzymes and poteasomes that digest a path through the jelly coat of the egg’ surface. The sperm cell membrane with a specific complex sugar in the egg jelly. These sulfate containing polyssacharides bind to specific receptors located on the sperm cell membrane. The egg jelly factors that inititate the acrosome reaction are often highly specific to each species.

Front 14

why can’t polyspermic eggs develop?

Back 14

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Front 15

what is EBR1?

Back 15

• A 350-kDa glycoprotein that displays the properties expected of a bindin receptor, isolated from sea urchin eggs

Front 16

what are the major events of egg activation in sea urchins/what is it?

Back 16

• The release of calcium ions that occurs when the sperm enters enters the egg is critical for activating the egg’s metabolism and initiating development. IP3 is the primary mechanism for releasing calcium ions from intracellular storage. PLC (phosolipase C) generates IP3, specifically the gamma class in sea urchins. The SRC family of protein kinases form a complex with PLC in the cytoplasms of sea urchin and star fish eggs. However SRC activity is activated by G proteins. Therefore in sea urchins it is though that the binding of sperm to the egg activates G proteins that activate SRC kinases then PLC gamma.

Front 17

what is sperm capacitation, what causes it ?

Back 17

• The set of physiological changes by which sperm become competent to fertilize an egg. It is caused by the change in resting potential of the sperms cell membrane by the efflux of potassium ions. Albumin removes cholesterol and this stimulates ion channels that allow calcium and bicarbonate ions to enter the sperm. These ions promote the activity of sperm specific soluble adenylate cylase, which makes cAMP from AMP. cAMP activates potein kinase A that activates tyrosine kinases. These kinases phosphorylate proteins that are essential for capacitation.

Front 18

What happens in species specific sperm zona binding?

Back 18

• The zona pellucida plays a role similar to that of the vitteline envelope in invertebrates but it is far moredenser and thicker structure. The binding of the sperm to the zona is relatively species specific. There are 3 major glycoproteins in the zona pellucida ZP1, ZP2, and ZP3. ZP3 initially binds sperm, initiates the acrosome reaction, crosslinks sperm receptors (galactosyltransferase-I) which activates G proteins which opens Calcium ion channels. ZP3-reacted sperm binds ZP2 (to retain attachment to the zona pellucida, and ZP1 crosslinks all in the zona.

Front 19

How are G proteins involved in Calcium ionentry into sea urchin eggs?

Back 19

1. Sperm contacts the egg and fuses, 2. G proteins are activated, 3. SRC kinases are activated, 4. PLC gamma is aactivated, 5. PLC splits PIP2 into IP3 and DAG, 6. Calcium ions are released, 7. Either cortical granule exocytosis, which slowly blocks polyspermy can occur, or 8. Inactivation of MAP kinase can occur, which reinitiates the cell cycle.

Front 20

What is the postulated pathway of egg activation in the sea urchin?

Back 20

the activation of PLC activates IP3 and DAG, ion which IP3 causes calcium ions release that causes degradation of cylcin and activation of MAP kinase, activation of NAD+ kinase and cortical granule exocytosis. DAG causes protein kinase C activation of sodium ions and loss of hydrogen ions, that increases intracellular pH.