adaptations of sperm and egg cells Flashcards
What type of nucleus do both sperm and egg cells contain?
Both sperm and egg cells contain a haploid nucleus, which carries half the genetic information from the parent to pass on to the offspring.
How do sperm and egg cells differ in terms of movement?
Sperm move actively and rapidly, while eggs are moved passively and slowly.
What is the primary function of food reserves in egg cells?
Egg cells contain food reserves (yolk) to provide the necessary nutrients for the zygote and embryo development after fertilization.
Why do egg cells have the structure of the zona pellucida?
The zona pellucida is a glycoprotein layer in egg cells that contains ZP3. It binds to sperm and allows one sperm to penetrate. After penetration, it is chemically altered to prevent further sperm from entering the egg.
What role do binding proteins play in the fertilization process?
Binding proteins in the egg’s plasma membrane help the egg fuse with the sperm’s membrane, allowing the sperm’s nucleus to enter the egg during fertilization.
How do cortical granules contribute to preventing polyspermy?
Cortical granules are vesicles of enzymes near the egg’s plasma membrane. When released, they alter the zona pellucida so that it becomes impenetrable to other sperm after the first sperm has entered.
What resources do egg cells provide to support the developing zygote?
Egg cells provide resources like yolk (a large volume of cytoplasm with lipids and food reserves), mitochondria (for ATP production), and centrioles (for mitosis) to support the development of the zygote and embryo.
What are the primary adaptations of sperm cells for their role in fertilization?
- Tail (long flagellum for forward motion)
- Midpiece (with mitochondria to produce ATP for energy)
- Head (streamlined and narrow to reduce resistance, with densely packed chromosomes)
How does the tail of the sperm cell aid in its movement?
The tail of the sperm is a long flagellum with a 9+2 microtubule arrangement that beats to generate the forward motion needed to propel the sperm toward the egg.
How do the mitochondria in the midpiece of the sperm cell support its function?
The mitochondria in the midpiece provide the ATP required for the tail’s movement, enabling the sperm to swim and move toward the egg.
What is the function of the receptors on the sperm’s plasma membrane?
The receptors on the sperm’s plasma membrane bind to the ZP3 glycoprotein in the zona pellucida, allowing the sperm to attach to the egg.
What is the role of the acrosome in sperm fertilization?
The acrosome is a sac of enzymes around the sperm’s head that digests the proteins and polysaccharides of the zona pellucida, enabling the sperm to penetrate the egg’s membrane.
How do binding proteins in the acrosomal membrane aid fertilization?
After the acrosome undergoes exocytosis, binding proteins in its inner membrane bind to proteins in the egg’s plasma membrane, facilitating the fusion of the sperm and egg membranes and allowing the sperm’s nucleus to enter the egg.
What is the primary competition between sperm during fertilization?
The primary competition is for the first sperm to reach and penetrate the egg, as only the first sperm to penetrate the egg will successfully fertilize it.
