Why There Are Two Sexes

Every cell in your body is a diploid cell!Diploid: having two copies of each chromosome. A full set of genetic material, consisting of paired chromosomes one chromosome from each parental set. Haploid: having only one copy of each chromosome.The only haploid cells in your body are gametes (eggs/sperm). This does not happen.You know why it's important to get the correct blood type in a transfusion, right?Because if you get A or B when you are AB, it can kill you.You are suggesting that one person expresses multiple blood types.Wrong wrong wrong wrong wrong. You do not understand what a chromosome is.Every cell has 46 chromosomes. 23 pairs.This is a chromosome pair. Here is a single chromosome on the left, a chromosome pair on the right. Here is a closer view. As you can see, one arm contains 2 strands of DNA.These are the 23 chromosomes in a diploid cell: Every cell in your body has a full set of these.Here is a picture of the location of the ABO gene (the red line) on chromosome 9: You get one copy of the ABO gene from Mom and one copy from Dad.Now. Let's apply this to the AB blood type.If Mom is type A, she can have two genotypes: AA, AO
If Dad is type B, he can have two genotypes: BB, BO
If you are type AB, you got an A from Mom and a B from Dad.
That means that one arm of chromosome 9 has A and one arm of chromosome 9 has B.Now. Let's discuss the nature of a gene.A gene is a specific genomic sequence on one strand of DNA. Since DNA is complementary, the other strand has the same sequence, in reverse order (DNA strands run anti-parallel).That means that one arm of chromosome 9 has two copies of the A gene, one on each strand, and the other arm has two copies of the B gene, one on each strand.When a cell divides, both strands replicate.Both strands are functional.The only known exception to this rule in X chromosome inactivation.Gene suppression does occur, at the level of transcription or translation. But entire strand suppression does not.Edited by molbiogirl, : No reason given.Edited by molbiogirl, : added picEdited by molbiogirl, : clarity and more pics

“at least one allele will be active” means allele A, B or both. Do not worry, I know genetics at least within boundary of this papers. I may misspoke, but you too wasn’t in a gratest shape:“ . they have the same location on the chromosome . ” not on the same but on homologous chromosomes, but I new what you ment. Today is two late and I have to go to work at 6 AM, but tomorrow (evening) can you draw the diagram of diploid cell and demonstrate that this is impossible to have AB blood type per my model and I will prepare my diagram.Thanks a lot,Mark

My bad. I should have said chromosome, not strand.

molbiogirl,I am including the diagram that illustrates my point:

Click here Per my model, independent distribution of chromosomes during mitotic cell divisions yields four types of cells types.Per existing paradigm the cell division yields only identical cells.

M, I give up.Since you can't see that a person who produced those 4 blood types WOULD BE DEAD, I can't help you.

molbiogirl: No. Erythrocytes of this person have all opportunity to be of correct type (AB).Try to think of the diploid cell that has only one pair of chromosomes and two alleles A and B of a particular gene.Let call this cell - Erythrocytes only if the combination of its chromosome types leads to expression of both alleles A and B.If during mitotic division the cell inherits chromosome types that lead to expression of allele A, B or None - these cells are not Erythrocytes any more, even their mitotic division may result in more Erythrocytes. This is what proposed mechanism of cell differentiation is about.This is all I can say. I think I need to pose, and try to understand what is wrong with my model or with my explanation.Thank you for trying.Edited by miosim, : No reason given.

molbiogirl,I noticed ambiguity in a way I used the term “genetically active” referencing newly synthesized DNA strands. It may be interpreted that the genes located on this DNA strand are continuously transcribed. In this case, I would understand your comment that
“ . a person who produced those 4 blood types WOULD BE DEAD . ”However what I meant is that this DNA strand is just accessible for transcription but still subjected to routing mechanism of gene regulation.So regardless that my model allows existence of all four cell types in reference to accessibility to genes A, B and AB, the regulatory mechanisms of cell and organism will insure that only AB cell type (Erythrocytes) expresses its phenotype.I wonder if this caused misunderstanding, especially that a few times I explicitly called these cell types as A, B and AB phenotypes, which is incorrect.In my papers, I will change the term “genetically active” to “genetically enable” and will clarify that it means accessibility for transcription by routing mechanisms of gene regulation. Edited by miosim, : No reason given.Edited by miosim, : No reason given.

Cope's "rule" is at best a general long term trend that averages out greater positive change with negative change in size, and at worst doesn't apply at all (to several species). I find that his concept is falsified by actual evidence of the change in size in humans from the beginning of agriculture to the middle ages (getting smaller) then with the advent of better nutritiion and medicine to the present day (getting bigger).There is a strong correlation with diet, nutrition and health and zero correlation with size of males to females. I thought you found him insightful and brilliant. This suggests that you may need to reconsider a lot of your concepts with a more skeptical point of view. I don't need to repeat what others have done. You seem to have a basic misunderstanding of how genes function, which would suggest that more information be acquired before making (shaky) conclusions.Enjoy.

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RAZD,Again, I will not defend Geodakyan’s theories because I know nothing about this area of biology.I accounted Geodakyan’s theories, because I was looking for any glues related to my hypothesis. His theories stroked me with unusual for biological publications internal harmony and boldness. However, because his theories were nothing to do with what I was looking for I didn’t follow and scrutinize them.To be honest, if I would have more time I wouldn’t let you to burry his ideas so easily, because I have more trust in the beauty of his ideas and his talent that in the your argument.But I have no luxury of spare time to investigate Geodakyan’s theories or your claim, and therefore, feel free to talk about Geodakyan’s theories and pretend that you know what you are talking about.But if you want to talk about my hypothesis I will not be silent and may expose not only my lock of competence but yours also.Edited by miosim, : No reason given.Edited by miosim, : No reason given.Edited by miosim, : No reason given.

Yes, fantasy is so much more fun than reality.Unfortunately for you reality is unaffected by your - or anyone's - fantasy.Enjoy.

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we are limited in our ability to understand
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RebelAAmericanOZen[Deist
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Message 1

One big problem I see with sexual reproduction ever happening would be that two of the same species in the same location would have to "evolve" to have the ability to reproduce sexually. Then those two would have to meet, fall in love (ha ha), and reproduce. Then their "children" must stay in the same general area and repeat the process. This seems to be extremely unlikely to me. It seems far more likely that anything that developed the ability to reproduce sexually would find that trait to be negative in the fight for survival, and it would die out.

Of course, if anyone thought that evolution actually worked that way it would, indeed, be a problem. But it doesn't so the problem you see doesn't arise.In general, evolution can't move in big jumps. What you seem to hint at in the above is "instant speciation" (saltation). This does happen but only under very special circumstances.Sexual reproduction simply will not arise that way.We see existing organisms that have various stages of part way between our dipolar sexual reproduction and asexual reproduction. Obviously if various stages exist now and work just fine then organisms could have gradually moved through those stages.

Hi, heygabbagabba. Welcome to EvC! NosyNed has already given a good answer to this objection, but I'd like to explain it in a little more depth.Primitive "sexuality" would be nothing more than the fusion of two cells into one with twice the genomic content. There would be no distinct "male" and "female" sexes, nor even "+" or "-" mating types: any gamete could fuse with any other, because they're all identical. Specialized "egg" and "sperm" would arise by degrees long after the original emergence of sexual reproduction.This isn't just conjecture, either: many organisms are known to have only one type of gamete, which can fuse with gametes of like type. This has been documented in many types of organisms. Some bacteria reproduce sexually by fusing with another bacterium to combine their genomes, then reproduce asexually as a completely different organism.In plants with only one type of gamete, it is called "homospory" (I'm not sure if this term is used outside of a botanical context).Furthermore, most unicellular organisms that can reproduce sexually can also reproduce asexually. So, it is unreasonable to assume that the first sexually-reproducing organism was an obligate sexual-reproducer, as you have. Such an organism would inevitably be capable of both sexual and asexual reproduction. Thus, it could divide once asexually, then the two daughter cells could reproduce together sexually. So, it's actually a good way to combine the advantages of both types of reproduction: the speed of asexual reproduction, plus the health-promoting genetic variation of sexual reproduction. So, it's actually a very good survival tactic.In fact, many of even the most advanced plants can do this.-----What I have found in conversations here on EvC is that laymen tend to think the world has clear-cut, black-and-white categories of things, and simply don't realize that most of the natural world exists in gradients. When a news article presents a simple story about the newest scientific breakthrough, or Ken Ham writes an essay about his newest-discovered hole in the Theory of Evolution, you should always remember that these people do not ever tell you the full story, because they never actually know the full story to begin with.In fact, literally nobody really knows the full story. But, scientists are the only people who are willing to publicize that information.

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-BluejayDarwin loves you.

If you had all asexual reproducing things swimming around. Developing the needed parts for sexual reproduction would take quite a few "random mutations", none of which would have a beneficial side effect until the point where they were fully developed. They would still have no benefit until another of the same species also developed the sex parts, only opposite (female or male).According to Natural Selection, the sexual parts that started to develop would, for many many generations, give no benefit.these seem like some relatively complex "random mutations" to happen to one member of a species. Then mutate again into the opposite sex, either another member of the species, or one of the descendants of the original guy that got the then useless sex parts.The fact that there are species with both sexual and asexual reproduction does nothing to prove sex evolved. Call me when we can find a species that reproduces via asexual reproduction only starts reproducing sexually.