sex linkeage!!! pls help... :) (1 Viewer)

[arls]

okay... i know sum ppl were explaining on mirc last night but im still having dillemmas..
i read the text book stuff some more.. and here is my problem:

so female = xx male = xy

If there is a deficiency it is almost always on the x chrom..... (eg haemophilia) females having 2 x chroms will have a second gene to 'fall' back on if one is deficient. it is rare that both alleles are deficient... however for males a deficiency in a non-sexual gene on the x chrom may be disastrous. males only have one gene for that characteristic becuase they only have one x chrom andif that gene is deficient problems will arise... eg haemophilia... (stuff from text)

thats all good but problem: why cant the male 'fall' back on the y chrom??? this is not making sense to me. what is so special about the x chrom in the female that makes it a 'fall' back gene?

if any1 can clear up my dramas it would be much appreciated!

 

[allrounda]

The Y chromosome does not hold that much information. All the Y chromosome basically does is determine that the individual is male.

The X chromosome contains information for a larger number of things, so therefore it is able to step up and help out if a deficiency is present on the other X chromosome.

Thats basically the only reason. I have never come across a more 'detailed' explanation. Hope it helps!

 

[arls]

thanks allrounda.. thas better... dont worry babydoll this is good.

 

[arls]

Originally posted by allrounda
The Y chromosome does not hold that much information. All the Y chromosome basically does is determine that the individual is male.

The X chromosome contains information for a larger number of things, so therefore it is able to step up and help out if a deficiency is present on the other X chromosome.

Thats basically the only reason. I have never come across a more 'detailed' explanation. Hope it helps!

thats certainly a lot better than my text book! why didnt they just write that in my text? woulda made it a whole lot easier!

 

[psycho_mushy]

Describe the inheritance of sex-linked genes, and alleles that exhibit co-dominace and explian why these do not produce simple mendalians ratios

Sex linked genes are genes which occur on the X or Y chromosome. These do no follow normal Mendalian genetics, as the sex of the organism must be looked at as well. Any sex-linked chromosome that appears on the X-chromosome would probably be expresses in the male as only one chromosome is in effect. Co-dominacen is when both alleles are expressed. An example of this is blood groups where A, B and O groups are expressed. As there is no recessive allele, simple mendalian genetics do not apply here

Morgan therised that certain characteristics were carried on the X or Y chromosome and if it was carried on the X chromsome and was recessive, only one X-chromsome needed to have the gene in order for the male to develop the phenotype. this is mush more likely than the feaml coming up with it neeeding 2 infected chromosomes. If carried on the Y chromosome then the male would have it only as the female has no Y chromosome.

hope this helps arls

 

[crazylilmonkee]

Y chromosome is relatively shorter than the X, hence unable to carry the other gene that may be able to cover up the recessive 'defective' gene

(there was a thread a while ago saying that males were dying out cos of the mutated X gene = Y, dunno if u read that.. pretty funny )

 

[arls]

Originally posted by crazylilmonkee
Y chromosome is relatively shorter than the X, hence unable to carry the other gene that may be able to cover up the recessive 'defective' gene
(there was a thread a while ago saying that males were dying out cos of the mutated X gene = Y, dunno if u read that.. pretty funny )

sucked in !!! Chicks are gonna rule the world!! i wonder if theres some feminist who goes around contracting and spreading sex linked diseases just so she can make the male population die out!!! how lucky would the last few males be though? all those women!!!

 

[psycho_mushy]

what about guys who are feminists? like me?

 

[arls]

Originally posted by psycho_mushy
what about guys who are feminists? like me?

no comment. im typeless. literallly.

 

[psycho_mushy]

no comment. im typeless. literallly.

what does that mean?

 

[xiao1985]

omg!!! u pplz makes me sick!!! both literally and literally

newaz, interstin fact tho...... ahahaha