gene 3

assalamualaikum w.b.t...


oke..ai ni baru nak hapdate belog pasal notes..
*pemalas betol..-.-
bukan apa,
dua tiga hari ni siyes mood nak study xde..
start dari hari jumaat malam tu,
sampai semalam..
then hari ni baru ade selera nak jenguk notes..
kalo x juz belek2 sikit2 je..
sungguh xkelihatan macam student yang nak ambik final exam hari kamis ni..
*oh no! sila jangan mention hari keramat tu ! >_<

semalam sampai petang tadi baca notes untuk pengajian malaysia..
though xberapa nak memenuhi ciri2 ingatan yang sepatutnya,
tapi oke la..
ingat la jugak sikit2..
alhamdulillah..

then lepas solat maghrib + baca yasin tadi ingat nak terus hadap notes..
tapi it seems imposibble je..
anggota2 tubuh xmo cooperate langsung ! -.-''

so tangguh dulu n around pukul 9.00 p.m hafal apa2 yang patot..
jam 10.45 p.m baru stat belek incik genetics..>_<''
sikap yang xpatot dicontohi oleh junior2..>_<

oke..lets begin..makin banyak lak yanie bebel..>_<"
sori2..

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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





with luv,

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