Re: Diploid and Tetraploid
- Subject: Re: [IGSROBIN] Diploid and Tetraploid
- From: P* B*
- Date: Wed, 24 Oct 2001 21:20:29 -0700
Sandy:
2N cells are those found in leaves, stems, roots and other non-sexual
(somatic) tissues. In mammals, the cells of arms, legs, hands etc are
mostly 2N. When an organism reproduces sexually they produce N cells
as pollen, ova, sperm etc. If the somatic tissues are 2N=22 that means
that most leaf cells have 22 chromosomes. A pollen grain from such a
plant has a reproductive cell with 1/2 the somatic number as does the
egg. These reproductive cells are N=11. In a tetraploid with 2N=44,
the reproductive cells have N=22. Just 1/2 the somatic number.
If you cross a diploid (N=11) with a tetraploid (N=22) you get a
triploid offspring with 2N=33. Since the chromosomes have to matched
evenly to produce good pollen or egg cells triploids are normally
sterile.
Hope this helps,
Phil Bunch
-----Original Message-----
From: Sandy Connerley <sandym@NORTHCOAST.COM>
To: IGSROBIN@MAELSTROM.STJOHNS.EDU <IGSROBIN@MAELSTROM.STJOHNS.EDU>
Date: Wednesday, October 24, 2001 20:44
Subject: [IGSROBIN] Diploid and Tetraploid
>Barry,
>I have found an abstract which references crossing diploid and
>tetraploid and it uses these symbols which I do not understand.
>Hopefully, you will take the time to explain them.
>
>diploid (2n=22) X tetraploid (2n=44) crosses
>
>I know the diploid has two strands of chromosomes, so is that what
the
>22 means?
>Why do both the diploid and tetraploid have the 2n? What does 2n
mean?
>This is probably pretty basic, and I do have a book on order, but it
>won't come until next week!
>Sandy
>
