genetic mutations

Graham Dellaire popa0206 at PO-Box.McGill.CA
Fri Sep 29 16:26:42 EST 1995


>   mckierke at ix.netcom.com (Kevin E. McKiernan ) writes:
>  I am trying to understand the concept of "spontaneous genetic
>  mutation."  Assuming such, when, during human development, might such a
>  mutation take place?  During entire gestation period, or during the
>  first few hours, days, weeks, months?
>  
>  Thanks for any help.
>  Kevin McKiernan
>  
>>>>
Mutations are  able to occur even right now in your mature cells dividing mitotically....
sometimes this is how cancers develop.  Now if they are to be hereditarily conserved
mutations, they need to occur in your gamete producing cells (testes or ovaries depending on
your gender) or at an early enough time in embryo genesis (or even in your father/mothers gamete 
s before the zygote was formed) to be transfered to cells that are precursors for the cells in your
testes or ovaries that produce gametes.

Basically "spontaneous" mutation can occur any time.  The are particular times (or tissue in 
which)  when mutations may occur at a higher frequency.  Any cell that is rapidly dividing, such 
as an embryo, can run the chance of missing a mispaired base and permanently producing a 
change in its DNA.  Skin cells for example also are rapidly dividing and are therefore more likely to 
incurr mutations in their DNA.  Environmental mutagens, UV light for example, can increase the 
amount of damage to DNA and thus the chance of not repairing it.  


I hope that gets you started
 G. 




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