Physiology Question [500 Points Reward]

[Jatt101]

So, I'm bored, so I'll test the intelligent of fellow QJ'ers on the subject of Biology.


Most biology/Physiology classes, you are told that all somatic nucleated cells in your body have the same chromosomal DNA, weather they express it or not. This of course, is wrong. Name one exception and you get a wopping 500 points.


(Ignore random mutations and chromosomal DNA is only valid, no mitochondria DNA).
People who are not allowed to answer this question:
Pope, Freeplay, cathugra(sp)...for obvious reasons.

[Realn0whereman]

does the answer have anything to do with all the chromosomes being different? i dont really understand the statement... cz each chromosome is different and there are then there are the autosomes...

[Soulphalanx]

nvm, read question wrong

[Archaemic]

*thinks about it*

...
Yeah, I'm no biologist, I don't know the answer to this one. Although, aren't different portions of DNA disabled in different portions of the body? I don't remember.

[FreePlay]

Well, I think it's beca---

People who are not allowed to answer this question:
Pope, Freeplay, cathugra(sp)...for obvious reasons.

awww.

[Siouxsie]

Gametes?

[Soulphalanx]

not gametes cuz they're not somatic cells

[Jatt101]

not gametes cuz they're not somatic cells

Right...Somatic cells are non-gametic cells. Autosomal DNA/chromosome are non sex determining chromosome (not X or Y). Hope that helps. And the reason why I said chromosomal so you won't take foreign DNA (such as viral DNA) into consideration.

And just to make myself a little clear: You are told that every* cell in your body has the same DNA but not all of it is expressed, ie Brain cells & Muscle cell have the SAME DNA but express what they are suppose to. But there is very notable exception to this relating to some cells.

You guys want a hint? :)

[Archaemic]

Wait a second...don't sperm/eggs only have half a chromosome?

*still doesn't really know what you're talking about, but is just going with the hints, however subtle they may be*

E] Oh, sperm/ova are gametes, nevermind.

[Jatt101]

Sex cells=/= Somatic cells.

Somatic cells are non gametes.

Heres a hint: thyroid gland.

[|-Anubis-|]

chimerism?

[Archaemic]

I'm guessing that he meant an example that happens in everyone, which chimerism definitely isn't

[Jatt101]

chimerism?

Nope.

I'm guessing that he meant an example that happens in everyone, which chimerism definitely isn't

lol yeah...in fact it happens every human and in most mammals. If it didn't you'd be dead. Comon guys...I gave you big hint with the Thyriod gland.

[J_C_103]

Well, in human females the chromosomes of white blood cells rearrange.

[Jatt101]

Well, in human females the chromosomes of white blood cells rearrange.

Thats Correct!!
...It happens in every human and most mammals.

B cells before leaving the bone marrow rearrange their DNA so they are monospecific (react to only one type of foreign antigen). So they only express one type of antibody on their cell surface out of 10^10 possible. This rearrangment picks one type of combination from hundreds of thousands of genes. So one B cell= 1 specific antibody!

They also go through something known as hyper somatic mutations, mutations that affect only 1 base pair coding for the antibody when they come in contact with specific antigen on a pathogen. This allows the prolifereated B cells to make antibodies with different variability, and those with high affinity become your memory cells.

Same thing happens in T cells, in the thyriod gland, where each T cell makes one specific receptor and MHC components out of 10^12 possible combination. It just deletes the other DNA.

In conclusion, your lympocytes don't share the same DNA as other cells or even with other lympocytes. So when your biology teacher tells you that all cells in your body have the same DNA, you can call him a liar.

[J_C_103]

Yay, When my class discussed this in minor detail we mostly talked about females.

[Jatt101]

500 points for you. I want to have another one of these...anyone else want another question?

[Sir_Axxewraith]

meh

I'm breifing on this in Biology atm

[J_C_103]

oh yesh

[ReneX]

well here a question how much is 1+1?

[J_C_103]

2

[Siouxsie]

11

[PSPgamer512]

well here a question how much is 1+1?

Me and your girlfriend, wait that joke is lame..

[Jatt101]

To keep this threads integrity I shall lock it. :twisted: