Wednesday, February 29, 2012

What happens to a cell AFTER it becomes diploid? Can it go through meiosis?

After a cell has become a haploid cell through meiosis, it becomes an individual by way of mitosis, since it has now had its correct number of chromosomes restored upon fertilization. Can a haploid cell itself go through meiosis? Is there any other fate of a haploid cell other than becoming an individual after fertlization? What about in plants? Thanks, I have searched everywhere and all examples of diagrams of cell reproduction are always with diploid cells, and nothing is said of haploid cells after they become haploid cells.What happens to a cell AFTER it becomes diploid? Can it go through meiosis?
What are you really asking?

Meiosis starts with a diploid cell and ends with 2 haploid cells which are your gametes. If a gamet is not fertilized, it dies (that is what happens during menstruation in women). If it is fertilized, then you get a diploid zygote which is your fertilized egg. Then the egg goes through mitosis and divided into similar cells and form an embryo and as the cells in the embryo divid even more and become more specific in shape and function, it becomes a fetus. Cells of the fetus divide even more (through mitosis) and become even more specific until finally an individual is formed (child).

A haploid cell won't survive unless it is fertilized (at least in diploid animals).



Read this paragraphs from Wikipedia:



Haploid and monoploidy:

The haploid number is the number of chromosomes in a gamete of an individual. This is distinct from the monoploid number which is the number of unique chromosomes in a single complete set.



In humans, the monoploid number (n) equals the haploid number (the number in a gamete, x), that is, x = n = 23. In some species (especially plants), these numbers differ. Commercial common wheat is an allopolyploid with six sets of chromosomes, two sets coming from each of three different species, with six copies of chromosomes in each cell. The gametes of common wheat are considered as haploid since they contain half the genetic information of somatic cells, but are not monoploid as they still contain three complete sets of chromosome from three species of organisms (n = 3x).



Most fungi and a few algae are normally monoploid organisms. Male bees, wasps and ants are also monoploid. For organisms that only ever have one set of chromosomes, the term monoploid is sometimes used interchangeably with haploid, but this is no longer the preferred terminology.



Plants and some algae switch between a haploid and a diploid or polyploid state, with one of the stages emphasized over the other. This is called alternation of generations. Most diploid organisms produce monoploid sex cells that can combine to form a diploid zygote, for example animals are primarily diploid but produce monoploid gametes. During meiosis, germ cell precursors have their number of chromosomes halved by randomly "choosing" one homologue, resulting in haploid germ cells (sperm and ovum).



Diploid:

Diploid (2n) cells have two copies (homologs) of each chromosome, usually one from the mother and one from the father. The exact number may be one or two different from the 2n number and still be classified as diploidy (although with aneuploidy). Nearly all mammals are diploid organisms, although all individuals have some small fracton of cells that are polyploidy.



Haplodiploidy:

A haplodiploid species is one in which one of the sexes has haploid cells and the other has diploid cells. Most commonly, the male is haploid and the female is diploid. In such species, the male develops from unfertilized eggs, a process called arrhenotokous parthenogenesis or simply arrhenotoky, while the female develops from fertilized eggs: the sperm provides a second set of chromosomes when it fertilizes the egg.



Haplodiploidy is found in many species of insects from the order Hymenoptera, particularly ants, bees, and wasps. One consequence of haplodiploidy is that the relatedness of sisters to each other is higher than in diploids; this has been advanced as an explanation for the eusociality common in this order of insects as it increases the power of kin selection. This argument has been disputed on the grounds that haplodiploidy also reduces the relatedness of brothers to sisters, theoretically balancing the above effect. In some Hymenopteran species, worker insects are also able to produce diploid (and therefore female) fertile offspring, which develop as normal queens. The second set of chromosomes comes not from sperm, but from one of the three polar bodies during anaphase II of meiosis. This process is called thelytokous parthenogenesis or simply thelytoky.What happens to a cell AFTER it becomes diploid? Can it go through meiosis?
When it becomes a haploid, a cell becomes a "germ cell" or a "gamete".



It fuses with another haploid to produce a diploid cell called "Zygote".



The process is called fertilization....



It is not genetically possible for a haploid to undergo meiosis. There is not enough raaw-material to begin with.

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