Help about the Cell Cycle and Meiosis?

Question

i have a biology test 2maro on the cell cycle and mitosis and meiosis. My teacher posted a study guide online and im confused about some of the concepts.
*why are there four haploid cells produced during oogenesis but only one gamete?
* and why isnt cytokinesis part of mitosis, i thought it was and know the study guide says it isnt.

Please help thanks

Answer 1

Penguin says >>

Oogenesis is the process of females creating egg cells... When women are born, they have a lot of cells that of those egg cells, only a few will undergo meiosis and form egg cells. Meiosis, yes, does form four haploid cells from each one of those "pre-made egg cells". All those four haploid cells has 23 chromosomes. However, Meiosis only ensures that there are enough chromosomes for the offspring, and not necessarily the quality of the egg cell...

What I mean is >> The larger egg cell containing more cytoplasm lives, while the other doesn't develope into an ovum.

In Meiosis I, the original cell divides into two, with 46 chromosomes. Meiosis does not seperate into two equal cells, as they do in mitosis. The larger cell then splits again [Meiosis II], and of the two haploid cells that result from Meiosis II, the larger one lives again. So, only one gamete is formed, though of the 4 haploids, 3 of the haploids degenerate.

-- Cytokinesis isn't part of mitosis...Mitosis is part of the cell cycle, which has 3 steps :: interphase, mitosis, and cytokinesis.

Remember that mitosis is the process of splitting a cell's nucleus.

and remember that cytokinesis only splits two cells in half by pinching the cell membrane...

So... there's a difference.

Thank -you-

<< Penguin waves good bye.

Answer 2

1. During the meiotic divisions of oogenesis, cytokinesis is unequal, with almost all the cytoplasm monopolized by a single daughter cell, the secondary oocyte. This large cell can go on to become the ovum; the other products of meiosis, smaller cells called polar bodies, degenerate. This is different to spermatogenesis where all four products of meiosis develop into mature sperm. So there is only one gamete (ovum) produced, the other cells are polar bodies which break down.

2. Cytokinesis is not actually part of mitosis itself, but it is part of the "mitotic phase" of the cell cycle which includes mitosis and cytokinesis.

Good luck for your test tomorrow =)

Answer 3

Oogenesis? Ah...ok, it occurs when only one egg is formed, the other 3 are polar bodies.
Cytokinesis is just the division of the cytoplasm when the cell splits...it should apply to both mitosis and meiosis.

Answer 4

while chromosomes line up throughout metaphase in meiosis I, the chromosomes line up analogous to a minimum of one yet another incredibly of linear. while the micro-tubules pull them aside, each and each new daughter cellular gets replicated pairs of chromosomes. In mitosis, the chromosomes are coated up linearly.