The Human Genome Project (1 Viewer)

[rosie-kide]

Hi everyone,

I was wondering if anyone has done any work on the Human Genome Project yet?

I'm stuck on a question I was given:

"How do linked genes change inheritance patterns"

Something along the lines of that. Any contribution to this question would be much appreciated.

Cheers.

 

[Mercurial]

haha, i juz asked a similar question.

We juz started it as well... kinda difficult stuff compared to the other topics.

I think it is because basic mendelian genetics deals with the separation of gene pairs on corresponding chromosomes. While linked genes are on the same chromosome. Therefore, during gamete formation there will b no segregation (separation of alleles). They will b inherited together.

However, during gamete formation they chromosomes duplicate to form 2 chromatids. When they separate to become haploid (1/2 the no. of genetic material) they split up. This sometimes leads to "crossing-over" where the linked genes get torn to the other side and swap positions causing recombinant types. Thus, an added variation in inherited patterns.

I dont understand the working out of dihybrid crossing linked genes though. Like doin the punet squares with them and setting out. If any1 can help pleez.

 

[rosie-kide]

Thanks!

Hey,

Thanks heaps on that. That sounded pretty thorough, and I'm going to have to learn that now.

Re: Dihybrid crosses

I have no idea either, I have so much to learn and to catch up on.
Just as well I need a tutor.

Sorry, I wish I could help you, since you helped me, but I'm afraid I have no clue. Good luck though.

 

[aby]

Originally posted by Mercurial

I dont understand the working out of dihybrid crossing linked genes though. Like doin the punet squares with them and setting out. If any1 can help pleez. [/B]

Hey! hopefully this will help.. it is my understanding of dihybrid crosses..
Dihyrbid crosses involve 2 characteristics, eg, height and leaf colour.
Say that 'H' was the dominant allele for 'tall' and 'h' was the recessive allele for 'short', and that 'W' was the dominant allele for 'white leaves' and 'w' was the recessive allele for 'black leaves...'
If we had to perform a parental cross of Tall and White (lets say TTWW) and short and black (ttww), the possible genotypes would be: TW only from one parents and tw from the other parents.
Therefore, if we had to do a punnet square cross, we would cross the alleles for 'TW' and 'tw'. The resulting F1 generation would be all be TtWw, ie tall and white (from the punnet square).

Say, for example, we wanted to cross this generation of TtWw with another TtWw.
The possible alleles are now TW, Tw, tW, tw for both... so we cross TW, Tw, tW, tw against a TW, Tw, tW, tw in a punnet square.... and combine the alleles to form lots of offspring with varying genotypes eg TW x TW from one of the crosses will give TTWW... etc. The ratio of the phenotype (what they look like) is usually 9:3:3:1...

Anyway.. try drawing up a punnet square again - it becomes easier after a while..

 

[Mercurial]

No worriez i try to help.

btw, thnx Aby explanation.