What occurs in each stage of meiosis?

Answer 1

=Meiosis is a nuclear division process that divides the parental chromosome number in half. Meiosis differ from mitosis, a nuclear division mechanism. Meiosis sorts chromosomes into parcels not one but twice. Meiosis occurs only in specialized reproductive cells. Meiosis consist of two divisions: Meiosis I and Meiosis II. In meiosis I, each duplicated chromosome aligns with its partner, homologue to homologue. after they are sorted and arranged this way, each homologous chromosome is pulled away from its partner. all homologues move apart from their partners and end up in two new nuclei. when the cytoplasm divides, there are two daughter cells with one of each type of chromosome. the chromosomes are still duplicated. Then, during Meiosis II, the 2 sister chromatids of each chromosome separate. they become individual, unduplicated chromosomes. there are now four parcels of chromosomes; each contains one unduplicated chromosome of each type. new nuclear envelopes begin to enclose them as 4 nuclei inside 2 cells.==Meiosis I: Prophase I, Metaphase I, AnaphaseI, Telophase I (Interphase: DNA is replicated prior to meiosis I)==Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II (No interphase DNA is not replicated prior to meiosis II)=

Answer 2

In prophase I of meiosis, each replicated chromosome pairs with its corresponding homologous chromosome. During metaphase I of meiosis, paired homologous chromosomes line up across the center of the cell. During anaphase I, spindle fibers pull each homologous chromosome pair toward the opposite ends of the cell. The next phase is telophase I, in which a nuclear membrane forms around each cluster of chromosomes. Cytokinesis follows telophase I, forming two new cells.

thats meiosis I.

Answer 3

Interphase...

This is not actually part of meiosis but it's worth mentioning because DNA undergoes semi conservative replicatiion to double the genetic content...

Meiosis can be split ibto 2 division Meiosis (i) and Meiosis (ii),

Meiosis (i)...

Prophase (i)...

* The chromatin (DNA) condenses and udergoes supercoiling so that the chromosomes shorten and thicken.

* The chromosomes come together in their homologous pairs, they bond to what's called an axiel element which essentially helps hold the chromosomes together, to form a bivalent; this process is known as synapsis.

*The non sister chromatids wrap around each other and attach at points called chaismata (single - chiasma).

* The DNA may now undergo crossing over. The DNA may break at the chiasmata. The broken ends of the chromatids may then rejoin to the ends of the non sister chromatids in the same bivalent. The sister chromatids may no longer be identical because the DNA swapped over maybe the same genes but it may be a different allele.

* The nucleolus dissapears and the nuclaer envelope disintegrates.

* A spindle forms made from protein microtubules - mostly from tubulin protein.

* The centreoles produce the spindle and move to opposite poles of the cell.

Metaphase (i)...

* Bivalents line up across the equator of the spindle attached to the spindle fibres at the centromeres.

* The chiasmata are still present.

*The bivalents are arranged randomly with each member of a homologous pair facing opposite poles.

* This allows the chromosomes to independently segregate when they are pulled apart in anaphase (i)

Anaphase (i)...

* The homologous chromosomes in a bivalent are pulled by the spindle fibres to opposite poles.

* The centromeres do not divide

* The chiasmata seperate and the lengths of chromatid that have been crossed over remain with the chromatid to which they have been newlt attached.

Telophase (i)...

* In most animal cells 2 new nuclaer envelopes form one around each set of chromosomes at each pole.

* The cells divide by ctyokinesis in animal cells

* There is a breif interphase in animal cells where the centrioles replicate.

* In plant cells the cell goes straight from anaphase (i) into meiosis (ii)

Meiosis (ii)

The division is in a plane perpendicular to meiosis (i) and is basically just mitosis.

Prophase (ii)

If a new nuclear evelope has reformed its breaks down again.

* The nucleolus disappears, the chromosomes undergo supercoiling (if they need to), the spindle forms and the centrioles move to the opposite poles.

Metaphase (ii)...

* The chromosomes arrange themselves on the equator of the spindle, attached at the centromeres.

* The chromatids are arranged randomly

Anaphase (ii)...

* The centromers divide and the chromatids are pulled to opposite poles by the contraction of the spindle fibres, segregating randomly.

Telophase (ii)...

* Nuclear envelopes reform around the haploid daughter nuclei

* In animal cells the 2 cells now divide by cytokinesis for a 2nd time to give 4 haploid cells.

* In plants cytokinesis starts in the middle (it starts at the plasma membrane for animals) where a new cell wall is made and a tetrad of 4 haploid cells are formed.

Answer 4

Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.

Answer 5

in the stages of meiosis a cell divides in half of the total no of chromosomes

Answer 6

meiosis is a type of cell division that results in two daughter cells each with half the chromosome number of the parent cell.

Answer 7

=Meiosis is a nuclear division process that divides the parental chromosome number in half. Meiosis differ from mitosis, a nuclear division mechanism. Meiosis sorts chromosomes into parcels not one but twice. Meiosis occurs only in specialized reproductive cells. Meiosis consist of two divisions: Meiosis I and Meiosis II. In meiosis I, each duplicated chromosome aligns with its partner, homologue to homologue. after they are sorted and arranged this way, each homologous chromosome is pulled away from its partner. all homologues move apart from their partners and end up in two new nuclei. when the cytoplasm divides, there are two daughter cells with one of each type of chromosome. the chromosomes are still duplicated. Then, during Meiosis II, the 2 sister chromatids of each chromosome separate. they become individual, unduplicated chromosomes. there are now four parcels of chromosomes; each contains one unduplicated chromosome of each type. new nuclear envelopes begin to enclose them as 4 nuclei inside 2 cells.==Meiosis I: Prophase I, Metaphase I, AnaphaseI, Telophase I (Interphase: DNA is replicated prior to meiosis I)==Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II (No interphase DNA is not replicated prior to meiosis II)=