Login

Join for Free!
114528 members


centromere

Discussion of all aspects of cellular structure, physiology and communication.

Moderator: BioTeam

centromere

Postby swatkat » Mon Mar 27, 2006 10:39 am

can a chromosome have more than one centromere?
User avatar
swatkat
Garter
Garter
 
Posts: 49
Joined: Wed Mar 22, 2006 9:40 am

Postby LilKim » Mon Mar 27, 2006 3:17 pm

if a chromosome is "created" with more than one centromere... This type of chromosome is very unstable it will eventually be broken and lost ... When this occurs, the cell is anneuploid and will ALWAYS die!!!

As with many things there are exceptions to this rules....

1. there are "things" called pseudo centromeres ... I guess they look like centromeres but don't act like them because one of the key centromeric proteins is absent. (can't remember the name of the protein ... i believe it's a histone protein though... This is seen in both normal people and cancer patients) ... so, these type of chromosome have one "good" centromere and one "non-functional centromere" ... therfore these chromosomes duplicate and segregate normally.

2. True Di-centrics (with 2 functional centromeres) are often seen in cancers. For whatever-unexplainable reason(???) these chromosomes can segregate normally ...occaisionally they break (resulting in acentric fragments) ... however the cell doesn't die???

(.. cancer chromosomes and cells tend to be rebellious and defy the rules!!!)
Last edited by LilKim on Mon Mar 27, 2006 4:58 pm, edited 1 time in total.
User avatar
LilKim
Coral
Coral
 
Posts: 436
Joined: Mon Mar 20, 2006 8:36 pm

Postby kitty82 » Mon Mar 27, 2006 4:37 pm

I'm pretty sure that each chromosome just has one centromere, hey take a look the picture of chromosome you'll see ... :)
User avatar
kitty82
Garter
Garter
 
Posts: 9
Joined: Wed Mar 15, 2006 3:55 pm


Postby swatkat » Tue Mar 28, 2006 5:54 am

ok
thx
just out of curiosity
and yes kitty82
i have seen the picture of the chromosome plenty of times :D
thx lilkim
that info on cancer cells was very interesting 8)
User avatar
swatkat
Garter
Garter
 
Posts: 49
Joined: Wed Mar 22, 2006 9:40 am

Postby sdekivit » Thu Mar 30, 2006 5:46 pm

in a robertsonian translocation actually a dicentric chromosome is created, but they act as one centromere.
sdekivit
King Cobra
King Cobra
 
Posts: 586
Joined: Sat Jul 30, 2005 7:16 pm
Location: holland

Postby swatkat » Fri Mar 31, 2006 10:15 am

whats a "robertsonian" translocation??
User avatar
swatkat
Garter
Garter
 
Posts: 49
Joined: Wed Mar 22, 2006 9:40 am

Postby sdekivit » Fri Mar 31, 2006 1:09 pm

search for it on google ;)
sdekivit
King Cobra
King Cobra
 
Posts: 586
Joined: Sat Jul 30, 2005 7:16 pm
Location: holland

hi

Postby swatkat » Fri Mar 31, 2006 6:32 pm

ok.. :D
i did find it on google
just one thing.....
the balanced and unbalanced forms of the acrocentric chromosomes are decided by the position of the centromeres,right?
User avatar
swatkat
Garter
Garter
 
Posts: 49
Joined: Wed Mar 22, 2006 9:40 am

Postby LilKim » Sun Apr 02, 2006 1:56 am

balanced means that no genetic information was lost or gained during a chromosomal rearrangement.

Unbalanced refers to if some DNA is added or deleted ... resulting in an "unbalanced genome" ... (Examples of unbalanced genomes and disease: turner syndrom=monosomy X or Down syndrome = +21)

However, with a classic robertsonian (when 2 centromeres fuse) no DNA is lost or gained... and this is considered Balanced.
User avatar
LilKim
Coral
Coral
 
Posts: 436
Joined: Mon Mar 20, 2006 8:36 pm


Return to Cell Biology

Who is online

Users browsing this forum: No registered users and 3 guests

cron