3 Comments

Do Bac­te­ria Age?

by Elio

A mi­cro­colony of E. coli de­vel­op­ing on agar from three neigh­bor­ing cells. ASM Mi­crobe Li­brary. Credit: J. Sha­pi­ro and C. Hsu.

The ques­tion arises: do bac­te­ria get old? Of course they do, their be­ing young im­me­di­ately af­ter cell di­vi­sion and old when they are about to di­vide again. But, in a differ­ent sense, do they age over many gen­er­a­tions? Or, as is com­monly as­sumed, does bi­nary fis­sion oblit­er­ate any dif­fer­ence be­tween sib­ling cells? The ques­tion has been stud­ied in de­tail by Eric Stew­art and col­leagues, with the sur­pris­ing an­swer that con­ven­tional wis­dom is wrong. There is a dif­fer­ence be­tween the growth rates of  "old" and "new" bac­te­ria. Sub­tle, but there. This ques­tion, and a re­lated one re­gard­ing the per­cent­age of vi­able cells in a grow­ing cul­ture, has been dis­cussed in a highly sat­is­fy­ing man­ner in a se­ries of posts on John Dennehy's illumi­nat­ing blog, Evilu­tion­ary Bi­ol­o­gist. I had a small hand in it, as this repar­tee re­minded me of an unas­sum­ing and un­pub­lished ex­per­i­ment I did one hun­dred years ago (or so it seems).

 

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3 Comments
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woan
18 years ago

Sounds good.Can we just think about hu­man cells.When we were baby,our cells are little.When we grow up,our cells get big and in large amount.So,didn't our cells di­vided from one cell to two,generation and generation,it be­comes more and big.
But we don't think our age is the time that one cell di­vide into two.So,why can we de­fine the bac­te­rias' age as the time that one di­vide into two?Cause they just have one cell?

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Amin talebi bezmin abadi
18 years ago

We have more than bil­lions of cells in our bod­ies,. They di­vide and grow up and die fi­nally, Bac­te­ria are ba­si­cally sim­i­lar to our cells, Why not!? it is not un­usual that we think they can be old or that they age!
We must re­spect them ! as im­por­tant mem­ber of our great earth !
Amin TALEBI
TARBIAT MODARES UNIVERSITY

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Biochem student
17 years ago

Bac­te­ria have a cir­cu­lar chro­mo­some which is repli­cated com­pletely every time it di­vides (un­less there are mu­ta­tions). How­ever, Hu­man chro­mo­somes are lin­ear and there­fore can not be repli­cated fully by a 5' to 3' poly­merase. We re­quire telom­erase to add ex­tra telom­ers to the end of the chro­mo­some so that it does not shorten with each gen­er­a­tion. How­ever, as we age telom­erase is ex­pressed in smaller quan­ti­ties. Our cells age with pass­ing gen­er­a­tions be­cause telom­ers are not added and our chro­mo­somes shorten. Bac­te­ria don't age be­cause their chro­mo­some is cir­cu­lar and can be com­pletely repli­cated by a 5' to 3' poly­merase.

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