Genetic problem

[Fidias]

Hi

 

Can you help with this problem? I've been arguing with a classmate. Thanks in advance

 

Chromosome 22 has about 700 genes in 48Mb of sequence, which represents 1,5% of the estimated 3200 Mb in the haploid genome. Using these numbers, how many genes would you estimate for the haploid human genome? If your estimate is significantly larger or smaller than the accepted value of 25,000 genes, suggest possible explanation for the discrepancy.

 

Is it as simple as a rule of three? if a chromosome contains 700 genes, 1610 genes contain 23 chromosomes, you agree? If that's how it resolves, then the reason for leaving fewer genes that are actually doing, is by the high density of repetitive DNA. (?)

Edited February 26, 2013 by Fidias

[CharonY]

Moved to homework. What is a rule of three? In any case, you have not considered the size of chromosome 22 (in relation to the rest of the genome).

[Fidias]

Thanks. However I do not understand how can I use the size of chromosome 22 in order to solve that question.

 

Rule of three is a cross multiplication:

 

http://en.wikipedia.org/wiki/Rule_of_three_(mathematics)#Rule_of_Three

[pwagen]

Hi

Is it as simple as a rule of three? if a chromosome contains 700 genes, 1610 genes contain 23 chromosomes, you agree? If that's how it resolves, then the reason for leaving fewer genes that are actually doing, is by the high density of repetitive DNA. (?)

What I think CharonY meant is that you can't say "if a chromosome contains 700 genes, then..." in this case, since chromosome 22 only makes up for 1.5% of the total genes. So instead, you'll have to work the percentage into the equation, instead of the number of chromosomes.

 

I'd tell you how I did it, but I got such a ridiculously high number, I'd embarrass myself. Good thing I didn't become a biologist.

 

Edit: Also, I think you meant 16,100, not 1,600? Minor point though.

Edited February 27, 2013 by pwagen

[Fidias]

[Yes, they are 16 100 genes, sorry]

So, considering that 1.5% corresponds to 700 genes, then 100% of the haploid genome have ~ 46 666 genes (?)

Therefore, as the estimated number of genes is higher - if it is properly calculated - as expected, the reason may be that gene density of chromosome 22 is higher than the other chromosomes in the body, right?

Edited February 28, 2013 by Fidias