Originally posted by OIO
the dna in a woman's egg is different from the one in a sperm. XX vs XY. When the sperm meets the egg the dna exchange begins.. the only way to make a woman knock another woman up would be to get her XX genes and snip off the part that turns the second X into a "Y" (to use extremely crude layman's terms here).
A sperm carries EITHER an X or a Y chromosome, while the egg only carries one X chromosome (in most cases). If the sperm that fertalizes the egg has the X chromosome, the child becomes a girl. If the sperm has a Y chromosome, it becomes a boy. In cases where the sperm or the egg carry two chromosomes (like XY, XX, ect), then you get into the realm of Klinefelter Syndrome (XXY chromosomes), which has some nasty genetic side-effects (infertillity being just one). Basically, you don't have to have the Y chromosome. If you did, everyone would be male.
As far as cloning goes, it is not the same thing. During reproduction, the DNA from the two parent gametes (mature sperm or egg cell) contain only 1/4 of the parent's DNA. Meiosis splits the full 46 chromosomal pairs into the haploid 23 chromosomes, and then meiosis II splits those chromosomes in half, with one chromatid per haploid going to each gamete. Therefore, each gamete has only one chromatid out of the total of four chromatids found in a regular chromosomal pair found in your average human cell.
Therefore, since there is only 25% of the parent's full DNA represented in each gamete (and crossover can occur along the chromatids), combining two gametes from the same creature will not result in a clone. ***edit: actually, my math was off...there is a 50% base chance of a genetic match occuring-ie a clone. However, due to gene swapping (chromosome pairs swapping genes between each other) during a certain phase of Meiosis I, this chance is greatly reduced***
(For those of you who have noticed that 1/4 + 1/4 does not equal 1, you have to remember that the chromatids combine and then double).
A clone is an exact DNA duplicate of a creature.
As per my link earlier in this thread, there is a species of lizards that is almost entirely female, and they do not need male lizards of their species to reproduce.
However, if we are talking about mammals specifically, due to what is called "imprinting," things become a little trickier. However, scientists have gotten around this with lab mice, and it is believed that it would be posible to do the same thing in humans., though there are ethical questions involved in undertaking such a procedure.
http://www.nature.com/nsu/040419/040419-8.html#