Chromosome Numbers

[memoryroad]

I have a quick question.

 

How many extra or fewer chromosomes can humans have and still survive?Does the same hold true for plants?

 

thanks

[Helix]

Do you mean not have Chromosome 12 for example? Missing an entire chromosome would be fatal, just based on the logical assumption of how many genes would be lost.

 

Also if that entire chromosome (or more than one) was lost during development then that cell wouldn't divide, it would senescence.

 

So, to answer your question; even one lost chromosome should be fatal. As for gaining, that would be intersting, I would suppose the organism would live unless the double protein expression induced RNAi, which would negate the protein's activity. That would be bad.

[sungmintd8]

There are some genes that probably wouldn't be fatal, but as far as chromosones, there is too much information that a human body needs. Now, as said, an extra would be mysterious, unless it is overriding an already needed process (its somewhat like a computer), which could contradict, or various other problems. Of course, don't get me wrong, but I'm not a biology, and such expert. I'm mostly in the chemical, computer, mathematics, and computer field.

[tman]

Humans can have an extra chromosome and still survive. If nondisjunction occurs (which is the failure of 2 members of a homologous chromosome pair to separate during meiosis) you can wind up with one less chromosome or even an extra chromosome. People who have Down Syndrome suffer from having 3 copies of chromosome 21, one chromosome too many. Despite having serious health problems someone with Down Syndrome can live a long life.

[Helix]

 

Now' date=' as said, an extra would be mysterious, unless it is overriding an already needed process (its somewhat like a computer), which could contradict, or various other problems.

 

[/quote']

 

It's not so much mysterious as it is an odds-game. We know how RNAi works, it's just the problem of knowing if it will kick in. When there is an overexpression of a protein (as there would be with two copies of a gene) then RNi (RNA interference) occurs. It is the process of the body putting out RNA strands complimentary to the genes template and having them bind--making the gene unable to be translated.

 

 

People who have Down Syndrome suffer from having 3 copies of chromosome 21' date=' one chromosome too many. Despite having serious health problems someone with Down Syndrome can live a long life.

 

[/quote']

 

That's really cool; I didn't know exactly how Down's played out genetically. It also sovles the issue of 'can we have more?' Down's must be a case where RNAi either doesn't occur or it does and that's partly responsible for the symtoms of DS.

[Mokele]

There's also Klienfelter syndrome (XXY males) and Turner syndrome (females with only 1 X). But for the most part, nondisjunctions are lethal, AFAIK

 

As for plants, they can have all sorts of weirdness, including being triploid (3 copies of each chromosome) and more. Increasing ploidy often results in unusually large and vigorous plants (modern strawberries are octaploid). Personally, I'd *love* to find a way to make some my plants polyploid; you'll know I've succeeded when a race of super-sized walking venus flytraps devours Cincinnati.

 

Mokele

[memoryroad]

thank you!

[Bluenoise]

Yep they're fatal for the most part. The reason that downs syndrome only occurs on chromosome 21 is because it's the smallest chromosome (besides y) so the genetic imbalance caused by the extra copy is less than for the other chromosomes. Also chromosomes are numbered from largest to smallest 1 -> 22. Uhhh and they messed up with 22 it looks smaller than 21 but it is actually slightly bigger.

[Skye]

Polyploidy leads to parthenogenic lizards.

 

I'm not sure about why it is so much less deadenating in plants, I suppose because their much simpler development.

 

Personally, I'd *love* to find a way to make some my plants polyploid; you'll know I've succeeded when a race of super-sized walking venus flytraps devours Cincinnati.

Colchicine is used commercially, it's also a drug.http://froogle.google.com/froogle?q=colchicine&hl=en&lr=&rls=GGLB,GGLB:1970-01,GGLB:en&sa=N&tab=wf

[Mokele]

Holy crap I love Canada's cheap drugs!

 

Now I just need to figure out how to actually apply it in the right way to cause polyploidy in my plants. It'll probably be easier to use it to cause polyploidy in asexually propagated cuttings than in flowers and such, I'm guessing, but I'll google around.

 

Bwahahahaha! You shall have your own personal army of monster Flytraps for this!

[sungmintd8]

It's not so much mysterious as it is an odds-game. We know how RNAi works, it's just the problem of knowing if it will kick in. When there is an overexpression of a protein (as there would be with two copies of a gene) then RNi (RNA interference) occurs. It is the process of the body putting out RNA strands complimentary to the genes template and having them bind--making the gene unable to be translated.

 

No, I'm saying that it would be mysterious if you had another chromosone that wasn't need, it was added, like two noses, and that would contradict that single nose that is already written. If it didn't contadict, like an added tail, that would be odd.

[Helix]

 

No' date=' I'm saying that it would be mysterious if you had another chromosone that wasn't need, it was added, like two noses, and that would contradict that single nose that is already written. If it didn't contadict, like an added tail, that would be odd.

[/quote']

 

Right, I understand. I'm saying that's not really possible. There is no "nose" gene. There isn't even noses genes. The formation of the nose is caused by tissue and blood vessels etc forming during development during certain conditions under biological signals. Since we aren't exactly sure how those work, recreating it wouldn't be feasible.

 

But, wow, wouldn't I love to have a tail...

[rakuenso]

Holy crap I love Canada's cheap drugs!

 

Now I just need to figure out how to actually apply it in the right way to cause polyploidy in my plants. It'll probably be easier to use it to cause polyploidy in asexually propagated cuttings than in flowers and such' date=' I'm guessing, but I'll google around.

 

Bwahahahaha! You shall have your own personal army of monster Flytraps for this![/quote']

 

What are the conditions needed to grow Flytraps?

 

Temperature? pH? soil conditions? etc. etc?

[Mokele]

It's offtopic, but it's really quite simple; they're native to South Carolina and have been effectively introduced in New Jersey. I grow mine outside (I'm in Cincinnati). All you need is a spot with full sun outside (they'll feed themselves), peat and sand (acidic, nutrient-less soil), and a bowl of distilled water to put the pot in (they need *only* distilled water, and need their soil to be very wet). Aside from that, just don't fertilize them (that kills carnivorous plants) and keep them in standing distilled water and they'll be fine. The same holds true for almost all other species, including American Pitcher plants and most sundews. Only a few species, like asian pitchers and sun pitchers require specialized care, the rest can grow outside just fine in most of the US.

 

Mokele