I don't understand Meiosis?

Question

I understand how the daughter cells have half of the genetic info of the parent, but if there are 4 daughter cells, how can they all have half? To make an analogy, how is it possible, to go from 1 basket with two eggs to 4 baskets with half, or one egg. HELP. I have a provinial tomorrow and I need to understand.

Answer 1

before the cell even undergoes meiosis, it makes a copy of all of its DNA and then the cell will undergo division two times.

So...the basket starts with two eggs...then makes two more eggs for a total of four. The basket divides once (each basket with two eggs). Each of those baskets divide again...for a total of four baskets each with one egg.

Answer 2

In people, the original cell has 46 chromosomes, but it's in the form of chromatin and the DNA has not doubled.

Before meiosis I begins, all the DNA is replicated or doubled. Then when the 46 chromosomes condense and become visible, each chromosome has two sister chromatids.

After meiosis I, the two resulting cells only have 23 chromosomes because the homologous pairs have been separated. However, the 23 chromosomes in each cell still have two sister chromatids so they look like clothespins or butterflies or Xs.

In meiosis II, the sister chromatids are pulled apart. That means that each new cell (all four of them) has 23 chromosomes, but they don't have two sister chromatids any more. They just have one.

So parent cell: 46 chromosomes
DNA doubles before meiosis begins.
After meiosis I: 23 chromosomes with 2 chromatids each
After meiosis II: 23 chromosomes with 1 chromatid each

Answer 3

In meiosis 1 the genetic info is copied and then 2 cells result with "2 eggs". Then Meiosis 2 occurs resulting in the seperation of the 2 cells with "1 egg"

Answer 4

http://www.bio-medicine.org/?q=/biology-definition/Meiosis

Meiosis (a Greek word meaning "decrease") is a cellular process that forms the basis for sexual reproduction, together with syngamy. It is a form of nuclear division by which a diploid parent produces four haploid daughter cells. The process includes the two stages of nuclear division (meiosis I and II), each usually accompanied by cell division. Single-stage meiosis has been suggested but not convincingly demonstrated. Duplication of chromosomes precedes the process of meiosis (during S phase). Most animals and plants are normally diploid, and use meiosis to produce sexual gametes, which fuse to form zygotes that develop into new organisms. In most animals this is often the primary or only means of proliferation. In other eukaryotes, sexual reproduction may play a more restricted role, while asexual reproduction gains emphasis (examples include plants and hydras).

The mechanistic differences between mitosis, which produces somatic cells, and meiosis, is best understood by considering mitosis first. (All jargon used in this article is defined in the article on mitosis.)

As described earlier, meiotic nuclear division consists of two stages, called meiosis I and meiosis II. It starts with a cell in the same state as does a mitotic division. However, the alignment of chromosomes for prophase is different. Homologous chromosomes join into tetrads (so called because each tetrad contains four chromatids), and the tetrads line up on the metaphase plane .

Answer 5

Meiosis 1 is basically the same as mitosis. Meiosis 2 is the same as mitosis, except that the genetic info is not replicated in either cell, so each of the new, new cells has only half the genetic info. Google "meiosis" and you will probably find some good animations that explain it. My biology teacher did that last year.

Answer 6

Meiosis
Gametes are special cells used in sexual reproduction. It is important that these cells contain 1/2 the normal number of chromosomes than the regular body cells (autosomes). When the sperm and egg unite the resulting zygote will contain the normal number of chromosomes for that organism. A special process called meiosis occurs in the reproductive organs to allow this to occur. Meiosis is a bit more complex than the cell cycle mentioned above; although many of the terms and stages show many similarities.
Before meiosis occurs the cell duplicates its chromosomes.
Interphase


Prophase I : The nucleus disappears, spindle fibers form , and the chromatid pairs form. A major difference occurs here separating this prophase from mitosis prophase. The chromatid pairs pair up with their homologous pair, forming a tetrad. This tetrad contains 2 original homologous chromosomes and their duplicates. The process of crossing over occurs during this time allowing for genetic diversity in the genome. Crossing over is a process where pieces of two homologous chromosomes, switch places and end up on the other chromosome. (1 cell )



Metaphase I : Tetrads line up along the center of the cell. (1 cell )



Anaphase I : The tertads split and move in opposite directions. During this phase the chromatid pairs move away from each other. (1 cell )



Telophase I : Two cells form each containing a complete set of chromosomes in the form of chromatid pairs. (2 cells )



Prophase II : The process continues moving the chromatid pairs toward the center of the cell. (2 cells )



Metaphase II : The chromatid pairs line up along the center of the cell. (2 cells )



Anaphase II : The chromatid pairs split moving the individual chromosomes toward the opposite poles. (2 cells )
Telophase II : Each of the two cells will begin to split in half and produce 2 more cells bringing the total to 4 cells. Each of these cells contain 1/2 the normal number of chromosomes. ( 4 cells )