genetic (notes)

assalamualaikum w.b.t...


lagi few days dah nak exam! >.<

so bear with me..saja nak share notes..

if bermanfaat untuk siapa2 silakan ambik :)

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genes ade dua jenis :

constitutive - "housekeeping genes" --> simple structure (constant)
controllable - expressed only when needed --> complex structure (only in certain condition)

gene regulation in prokaryotes :
-a set of gene which is regulated or controlled by ONE PROMOTER

structure :
-cistrons (code for specific protein)
-promoter region
-operator region
-regulatory region

function :
-catabolic (lac operon)
-anabolic (ara operon)


LAC OPERON

how it works ?

--> in the absence of lactose,the repressor protein binds to d operator region..RNA polymerase (RNAP) cannot bind to d promoter region..there's no transcription occur..genes are not expressed..

-->in the presence of lactose,d lactose will bind to d repressor protein n change in shape..so dat d repressor protein cannot bind to the operator region coz of d change of shape..the RNAP can bind to d promoter region,transcription occur n mRNA produced ! ^_^

gene regulation in eukaryotes :

-transcription - level of regulation

-mencegah penggumpalan mRNA

-no translation when not needed

regulatory pathways :

-hormones

-DNA structures (histones n chromatin packaging)

-enhancers

-DNA-binding protein

-transcription factors

key : has David end D-boring talk ?

*the more the protein bounds to the DNA,the less the transcription (sebab lagi ketat)

GENE MUTATION

mutations :

- changes in nucleotide sequence in DNA

- MAY occur in SOMATIC CELL --> not passed to d offsprings

- MAY occur in GAMETES --> MAYbe passed to d offsprings

- jarang berlaku

- repaired by enzymes

chromosomal mutation :

- mungkin melibatkan perubahan struktur kromosom

- deletion a part of chromosome

jenis :

-deletion

-inversion

-translocation

-nondisjunction

-duplication

DELETION :  

                                          

-due to d breakage

-a piece of chromosome hilang

INVERSION :

-chromosome segment break off

-segment jadi upside-down then reattaches

DUPLICATION :

-berlaku bila gene sequence is repeated

TRANSLOCATION :

-melibatkan dua heterozygous chromosomes

-part of one chromosome is transfered to another chromosome

NONDISJUNCTION :

-kegagalan chromosomes untuk separate semasa mitosis

-menyebabkan gamete mempunyai lebih atau kurang chromosomes

disorder :

--> down syndromes (three 21st chromosomes)

--> turner's syndromes (single X chromosomes)

--> klinefelter's syndromes (XXY chromosomes)

CHROMOSOME MUTATION

--> virus that can affect DNA..the virus will inject the DNA and affect the code..for example,the original code is ABCDEFGHI but the affect code will be ABEGHICDF 

GENE MUTATION

-change in the nucleotide osequence of gene

-may only involve single nucleotide

-mungkin disebabkan copying error,virus kimia n etc

types :

-point mutation

-substitution

-insertion

-deletions

-frameshift

POINT MUTATION

-sicle cell disease - result of one nucleotide substitution

-berlaku kat haemoglobin gene

-example of point mutation-

FRAMESHIFT MUTATION

-inserting or deleting one or more nucleotides

-change the 'reading frame' like changing a sentence

-proteins built incorrectly

example : kalau code yang normal,mesti ada tiga,tiga kod kan..but kalau yang frameshift mutation,salah satu kod hilang..

RECOMBINANT DNA

-placing a relevant gene on an organism's DNA

-organism required a specific trait carried by exogenous DNA

-example : recombinant human insulin

 

okeh..setakat tu je dulu :*

 

xoxo,

yanie