doghouse

From the Department of Inconsequential Corrections:
Actually a mule is the result of a female horse (mare) mated to a male donkey (jack).

A hinny is out of a female donkey (jenny) by a male horse (stallion).

And I’m not sure you could tell the difference between a mule and hinny without knowing their parents.

Carry on.

KC

Hmm...I always thought honeybee males had the haploid number of 16 chromosomes, while the queen had the diploid number of 32. In essence, the entire genome acted as a sex chromosome.

Are you saying males have 15 paired chromosomes and one lying about free?

KC

Non-praying Mantis

IIRC, nerves and muscle cells divide very rarely, if at all. So your brain cells would be the same as those which you had when you were born. At least, that appears to be the modern consensus.

Actually, I am implying in my above post that this would NOT be true. Liver and heart cells diverge early in development because liver derives from endoderm, and the heart derives from mesoderm. These two types (there are three - the other is ectoderm that forms the skin and nerves) of tissue layers separate in the very early stages of development. There are many cell generations between them (from their common "ancestor" cell) by the time that birth takes place. Also, the liver cells replicate much faster than heart cells.

I am saying that, although they are very similar to each other, the DNA that is in your liver cell is different than the DNA that is in your heart cells.

NPM

pz

Apparently, some people who are familiar with the breeds can distinguish a mule from a hinny more often than not, but the error bars on that determination are large. The differences are supposedly subtle and within the range of variation of both types.

I can't attest to their reliability personally, because they do look pretty much the same to me.

Except for the ones that talk. We know they are all mules.

pz

No, you're right, my error. I was thinking of Protenor sex determination, which is exactly the condition you describe above -- but honeybees and other eusocial insects are fully haplodiploid, with drones the product of parthenogenesis.

Non-praying Mantis

Nope. Male hymenoptera (ants, bees, and wasps) are actually haploid, at least in the social and subsocial hymenoptera (I'm not sure about the sawflies and other hymenoptera). They are produced from unfertilized eggs, therefore, they have no genetic contribution from the father, and therefore have only the mother's genes. Since the eggs are still produced in the same way (from meiosis) and are haploid, the males that develop from them never receive the "other half" of their genes, and are also haploid. By the way, the above method is called haplodiploid sex determination.

Grasshoppers and crickets use a system where they have an unpaired/paired sex chromosome which determines male or female. Females are XX (two paired chromosomes) and males are XO (where "O" indicates a missing chromosome). All offspring result from fertilized eggs in this case.

Edited to add: Oops, I see a bit of cross-posting here...

NPM

KC

Regarding Protenor, it never ceases to amaze me just how much variation there is in sex determination systems.

KC

zwi

Let me try and make this clear.


Consider any non sex linked mammalian chromosome. Forget about the birds and the bees, and the gymnosperms.

There is a germ cell line, which replicates by mitosis, copying all the genes and all the alleles. This includes the expressed ones and the unexpressed ones.

hold on moderators and others

The last division is meiotic, and of each pair of alleles only one is copied to the patrticular chromosome we are considering So a chromosome 5 in one of your spermatozoa will be made up of a series of bits of DNA that came to you from your Daddy and some others that came from your Mommy

There will also be junk DNA and all the rest, but we are just considering the real McCoy DNA OK? That haploid chromosome will be intrinsically different from all your other, diploid DNA It will be a different series of bases

Then if that chromosome is very lucky it will be matched up with another haploid chromosome 5 and result in a diploid but unique Chromosome 5 Then if your streak of luck continues the zygote you are in will be implanted into a uterine wall and perhaps an individual will eventually be born

But my point is that the chromosome 5 in the haploid state is distinct from all the other chromosome 5s that are in the body, and in the diploid state it is distinct again

And now boys and girls, comes the result of posing questions in a nonstandard way

Now repeat after memammals are metazoa

This should be clear even to mules in rural Minnesota

Here is an ancient riddle

Which came first, the chicken or the egg?

Now, if you have followed me, you will know that the egg must have come first. It is distinct from the owner of the ovary

Enjoy. Its funny and lighten up

Zwi

pz

Barring unequal crossing over, though, the set of genes is unchanged. They have a different mix of alleles.
The point of mentioning junk DNA here is...?

I think you are going off in irrelevant directions. Your comments here boil down to the fact that chromosomes in gametes have undergone recombination. That doesn't change the fact that the cellular products of meiosis have a complete complement of genes.
Errm, OK. I did not realize that this was a point of contention, or that we needed to pose questions in a "nonstandard way" to realize it.
For someone who is extraordinarily sensitive to perceived insults, you are strangely ready to throw around insults of your own here and in private messages.

This is an official warning: lighten up.

If you had paid any attention to my earlier comment about alternation of generations, you'd know that the old chicken/egg question is simply a malformed concept that is a classic example of trying to shoehorn a continuous process into a discontinuous binary choice -- it's a false dichotomy.

zwi

pz

But I am talking about mammals

I always was

If you felt I insulted you I apologize

I felt that your remark that I exhibited metazoan bias, was an insult

It would have been nice if you expressed in that PM that you did not intend to insult A soft answer turneth away wrath

Sorry and I will lighten up Gosh I thought I was very light, but I guess it was not thought of as being funny

Zwi