no. of chromatids,dyads and tetrads

by **yee** » Tue Jan 03, 2006 4:30 am

anyone pls help me to know how many chromatids are there in a simple

chromosome(one or two)

i think i'm missing the main concept in genetics

i m lost in tetrads and dyads too

by **Enzyme** » Tue Jan 03, 2006 10:05 am

Mmmm... I think I don't know exactly the question you want to ask. Sure that I misunderstood, tell me.

In a simple chromosome there are two chromatids (also there are chromosomes with one chromatid. For example, before starting the mitosis, in G1 chromosomes have one chromatid).

But there are species which can have more chromatids, as Drosophila melanogaster, Chironomus tentans, etc which has politenic chromosomes (they round a thousand of chromatids).

About dyads and tetrads, dyads are the result of the first meiotic division in cells which has cell wall and tetrads are the result of the second meiotic division in those cells too. For example: in germinal cells of plants.

Did I answered your question?

by **aaroncjj_2020** » Mon Jan 16, 2006 2:21 am

in an easier way, in normal chromosome, there are one chromatid. when it undergo mitosis, during interphase, it'll duplicate the genetic material, and now the chromosome has two chromatids. during anaphase the two chromatids(sister chromatid) will separate and produce two chromosomes, each with one chromatid. hope this can help u.

by **yee** » Tue Jan 17, 2006 3:18 pm

thanks for the explanation

however, i want to make sure whether my understanding really true

so,please let me ask u one question

that is ...does a simple chromosome have one chromatid and one centromere only?

P.s i tried to attach a file using paint but it is not an allowed extension

Looking forward to ur reply...

by **MrMistery** » Tue Jan 17, 2006 7:27 pm

If you want to attach pictures be sure to save them in a *.JPG format, as we do not allow *.bmp, because of file size.
About centromere, that is only prezent during cell division, when homologos chromosomes attach

by **aaroncjj_2020** » Wed Jan 18, 2006 2:13 am

err....i hv a different point of view. every chromosome hv a centromere and a chromotid.

by **yee** » Thu Jan 19, 2006 4:02 pm

here is the attach file

pls choose the right one by telling 1st ,2nd or 3rd pic

by **aaroncjj_2020** » Fri Jan 20, 2006 8:54 am

left top pic

by **Enzyme** » Sat Jan 21, 2006 3:17 pm

In your diagram: The correct pic is the one which is in the left top (the first one). The second pic misunderstands chromatid with chromosomic arm. And the third is wrong too.

Here I'm sending you another diagram. I hope it will be useful for you...

no. of chromatids,dyads and tetrads

no. of chromatids,dyads and tetrads

thanks

thanks mr mistery

Who is online