Monday, April 04, 2011

gara gara exam...GENE MUTATION..

a few days more left before my final exam..deep in my heart im still hope that i can get another A in biology....
so,in order to refresh my mind i would like to test myself about GENE MUTATION.....

why in blog???????.....
this is because i've finished all the past year question and all exercise,,no harm done if im using this THEADMIRE HUNKZ.BLOGSPOT as my "revision corner".....hahaha
lets begin..

what is gene mutation??..
gene mutation occur when there is change in nucleotide sequences of DNA in a gene..There are 4 types of gene mutation namely base substitution, base inversion, base deletion and base insertion.

Base substitution occur when one or more base pair in nucleotide sequence in a gene is substitute.Base substitution can result change in codon.Change in codon will result two different condition liken missense mutation and nonsense mutation.Missense mutation occur when there is change of amino acid.For example amino acid valine replace glutamic acid.This will cause sickle cell anaemia.Nonsense mutation occur when a codon become stop codon.

Base insertion occurs when there is insertion of one or more nucleotide sequence in a gene.

Base deletion occur when theres a deletion of one or more base pair in nuleotide sequence in a gene. Base deletion can lead to major thalassaemia.

Both base insertion and base deletion are fatal.This is because there can cause frameshift mutation.Frameshift mutation occurs when there are deletion or inversion of nucleotide sequence at mutation point. Thus it will shift the reading frame by one or more bases. Then,gene will be read in the wrong three base group or codon. So,starting from the mutation point the coding sequence of amino acid is changed and this changes will caused different protein is produced.

Base inversion occur when one or more bases pair in nucleotide sequence is inverted.

Wallah....thats all about gene mutation..done

p/s : sajer nak menconteng my blog and maybe share...