protein synthesis

1. With the name of Allah the most
gracious and merciful.

2. THANKS TO SIR.
RAHMAN ULLAH……
THAT TEACHES US
WHOLE HEARTEDLY
WITH
SINCERTY…………

3. Name: SALAH UDDIN.
Topic : protein synthesis…

4. Central dogma
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5. Central dogma : All
organisms use the same
basic mechanism of
reading and expressing
genes….

6. Central dogma

7. Over view

8. PROTEIN SYNTHESIS…….
Or,
GENE EXPERISION.

9. Step 1st :Transcription:
1>Initiation phase.
2> elongation phase.
3> termination phase.

10. Step 2nd :Translation:
1.Activation of amino acids.
2.Formation of initiation complex.
3.polypeptide elongation
4.termition

11. TRANSCRIPTION…………..
.formation of mRNA from
DNA Sequence encoding
the gene is know as
transcription.

12. The enzyme
used in
process Is
RNA
polymerase.

13. Mechanisms of
transcription:
Transcription is long
and lengthy process
which mainly
completes in 3 phases.
Which are disussed
as:

14. initiation phase…
this phase occures when RNA
polymerase binds the promotor
region of DNA.
In prokaryotes the promotor is
TATAAT also known as -10 seq.
and TTGACA also known as -35
seq.
In eukaryotes.
TATA -25 seq.
CAAT -70 seq.

15. These position
are located are
located before
initiation site of
structural region
of the gene.

16. mRNA.
It has three sub
unites
Beta.
Beta.
Sigma.
Sigma factor.

17. The first 3 enzymes are
called core enzymes required
for polymerase activity.
While 4th is used for binding
promotor.
Diff. Sigma factor doesn’t
require a primer.
Similarity .DNA polymerase
binds to 3 end of growing
polypeptide.

18. In prokryotes only one type
of RNA is found.
In euk . 3 kinds.
RNA poylmerase 1
synthedize rRNA.
RNA polymerase 2=mRNA
RNA polymerase 3 =tRNA

19. 2) elongation phase…..
In elongation phase
formation of mRNA
continues till
termination occures.

20. Important events to occur.

21. .Sigma factor releases.
.Core enzyme extand the
polymerase activity.
.One strand act as a tampleat.
.This tampleat strand act as a
antisense buz mRNA is
complimentary to this strand while
the other one is known as coding or
sense srand.
In elongation phase RNA
polymerase keep on moving from 5
to 3 direction.

22. Transcription bubble
moves along the
DNA.
This event continues
till the RNA
polymerase reaches
the terminator
region.

23. 2)Termination
phase……………..
A region known as
terminator region one gene
stops the synthesis of
mRNA.
The region contain GC
base pair which is followed
by AT base pair.
GC hairpin….

24. The part of mRNA which
transcribed in the region
containing GC base pair and AT
base pair.
The mRNA formed in this
region formed a structure
known GC hairpin.
.the GC pin is followed by AU
tail.
.This GC hairpin cause stoping
mRNA formation

25. Post transcriptional
modification……..
Formation of functional mRNA from
the primary mRNA.
. phosphatase and nuclease enzyme.
Exon…..protein coding part.
Intron….. non-protein coding
sequence.
.Addition of cap and tail.
>Cap is fom of….. 7-methyl GTP.
>Tail is fome of….. poly-A- tail.

26. -

27. 2nd main stage…..
Translation………

28. The decoding of mRNA to
produce a specific amino
acid seq. or polypeptide.
Which will letter fold into
active protein.
In prokaryotes it occure in
cytoplasm.
In eukaryotes…???????

29. 1)Activition: binding of
free aminoacids with 3
end……………complex
formation kmown as
aminoacyl tRNA
complex.
This binding is
catalyzed aminoacyle
tRNA synthase.

30. Formation of initiation complex…
Translation actually begins with
formation of initiation complex.
>combination of rib.sub
units,mRNA,first aminoacid and
tRNA.
>chemicaly modified methionine
binds to smaller sub unite.
This bindinding iz controlled by
enzyme initiating factor

31. With help of another , 5 end of
mRNA binds to the ribosomes.
IC formation completes when larg
sub unit combines.
3- sites on larg subunit.
1> p-sites,,,,,peptid bond will form
b/w successive A.acid.
2> A-site……. Successive tRNA
bearing A.acid will attached.
3> E-exit……here tRNA will leave
ribosomes during elongation
phase.

33. Polypeptide elongation:………………..
The ribosomes sub unite move
along mRNA and peptide
formation occure.
3-steps which occures
repeatedly.
1>When the codon of mRNA iz
exposed to A-site its anticodon
bearing aminoacyle tRNA complex
binds to it with the help of enzyme
“ elongation factor”.

34. 2> when the enyme “peptid transfarase”
is emerged from p-site it removes
A.acids from tRNA on P site and binds
to newly coming A.acid with help of
P.bond.
3> translocation: 5 to 3 end,,,
Empty tRNA reached to E…….leave…..
Another tRNA having A.acid is shifted
from A to P site and another codon iz
exposed to to A-site.
All the above 3 steps repeats again and
again until stop codon reaches…

36. .

37. Step 3rd
“””””””””””””””””TERMINATION.
Elongation continues until non-sense
codon exposed to A-site….
Non-sense codon do not binds to
tRNA but recognized by release factor
and terminates the process of
translation.
Two sub-unites again separates from
mRNA.

38. .

39. -

40. .

41. ,

43. THANKS
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