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Someone please answer my basic chromosomes and genes questions--->

Never really understood chromosomes properly and now that it's come up again at a2 bio im lost so I need some things cleared up:
(also correct my mistakes please)
The X is made up of 2 chromatids. Each of your cells contains chromosomes both from your mum and you dad (so you have loads of pairs of X's one from your dad and one from your mum) 2 chromosomes that contain the same genes are called a homologous pair.(is this correct?)
A chromatid is a strand of DNA and a chromosome is just a pair of identical chromatids linked by a centromere.
In meiosis a homologous pair of chromosome is split so each chromosome is put into a different daughter cell and then in meiosis 2 these chromosome are then split in chromatids in different daughter cells.

In mitosis all the chromosomes both from your mum and dad are split by their centromeres and each chromatid is put into 2 daughter cells, so cells prtoduced are also diploid whereas in meiosis the cells produced are haploid.

Reply 1

Clare~Bear

Homologous pairs - two cromatids that make up a chromosome are referred to as a homologous pair I think, or is it, when they replicated and you have two chromosomes that are indentical :confused:

I used to be confused as to how strands of DNA fit into a chromosome, but my A2 book has a good picture of it . . . this isn't the exact one, but it shows the same things . . . .

(edited 12 years ago)

Reply 2

Mocking_bird

Original post by Clare~Bear

Homologous pairs - two cromatids that ake up a chromosome are referred to as a homologous pair.

Pretty sure a homologous pair is a pair of chromosomes (that have the same length, gene loci, gene sequence etc), not just two chromatids.

But besides that OP, i'll deffo come back here tomorrow and answer your question in more depth if nobody else has. Its a little too late for me to put it down coherantly at the moment :laugh:

(edited 12 years ago)

Reply 3

Yasin-Ali

Original post by Mocking_bird

Do it even if someone else has!

Reply 4

Amandeep_Psych07

Original post by Clare~Bear

That is such a helpful picture! It has been confusing me for ages. :colondollar:

Reply 5

arvin_infinity

Original post by Yasin-Ali

The X is made up of 2 chromatids. Each of your cells contains chromosomes both from your mum and you dad (so you have loads of pairs of X's one from your dad and one from your mum)

See post above but as for the bold bit, by X you mean a chromosome I guess!?

I mean, bear in mind you didnt get 46 chromosomes from your dad and mom like for each cells in your body- the 46 chromosomes only inherited once in your life time

Its like there was a zygote which had the 46 chromosome then you get all your cells (with 46 chromosomes ) from the zygote

if you see what I mean ..