Defination of translation Components of translational machinery 1)Transfer RNA 2)Aminoacyl tRNA synthetase 3)Ribosomes 4)Messenger RNA PROKARYOTIC TRANSLATION EUKARYOTIC TRANSLATION NECESSITY OF TRANSLATION CONCLUSION

1. By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

2.  Defination of translation
 Components of translational machinery
1)Transfer RNA
2)Aminoacyl tRNA synthetase
3)Ribosomes
4)Messenger RNA
PROKARYOTIC TRANSLATION
EUKARYOTIC TRANSLATION
NECESSITY OF TRANSLATION
CONCLUSION

3.  The process by which messenger RNA is
translated into proteins.
or
 The process in which the genetic information
presents in an mRNA molecule specifies the
sequence of amino acid during protein
synthesis.

4.  It basically includes following components-
1) Transfer RNA
2) Aminoacyl tRNA synthetase
3) Ribosomes
4) Messenger RNA

5.  All cells contain a set of transfer RNAs (tRNAs),
each of which is a small RNA molecule length
between 70 and 90 nucleotides
 Each having at least one type of tRNA assigned to
it. Before an amino acid is attached by its carboxyl
end to the 3' end of an appropriate tRNA
molecule.Linking covalently the amino acid to a
tRNA containing the correct anticodons

6.  Each tRNA molecule recognizes a specific codon.
Transfer ribonucleic acid (tRNA) is primarily
synthesized from tRNA gene through transcription
by RNA polymerase.
 Synthesis of tRNA is regulated by promoter
activity and specific factors (ppGpp and/or
pppGpp in prokaryotes and Maf1 in eukaryotes)
depending on the nutrient condition of the cell.

7.  Primary transcripts of tRNA genes contain 50 and
30 extra sequences, which are removed by a set of
responsible nucleases.
 In some cases tRNA transcripts contain introns,
which are spliced out by a specific endonuclease
and the resultant two fragments are joined by
RNA ligasess

9.  the loop closest to the 5' end is called the
dihydrouridine arm (D arm), as contains
dihydrouridine bases, ( unusual nucleotides
common only to tRNA).
 The loop closest to the 3' end is called the T arm,
after its sequence of thymine-pseudouridine-
cytosine (pseudouridine is also an unusual base).

10.  bottom loop of the cloverleaf contains the
anticodon, which binds complementarily to the
mRNA codon.
 At the 3' end of the tRNA molecule, extends a
three nucleotide acceptor site including a free -OH
group.
 s A specific tRNA binds to a specific amino acid
through its acceptor arms.

11.  some tRNA molecules can bind to two or three
different codons. 3' end of the anticodon is more
spatially confined than the 5' end resulting the 5' end of
the anticodon free to hydrogen bond with several base
groups located at the 3' position of the codon. This idea
is called the wobble hypothesis . The 5' position is
called the wobble position because it can move The
wobble hypothesis means that if the first and second
positions are the same.

12.  The attachment of amino acids to specific tRNAs is
mediated by a group of enzymes called aminoacyl tRNA
synthetase( Paul Zamecnik, and Mahlon Hoagland in 1957)
 amino acid + ATP → aminoacyl-AMP + Ppi
 aminoacyl-AMP + tRNA → aminoacyl-tRNA + AMP
 Sum of 1 and 2: amino acid + tRNA + ATP → aminoacyl-
tRNA + AMP + PPi

13.  Class I
 has two highly conserved sequence motifs
 usually monomeric or dimeric.
 Class II
 has three highly conserved sequence motifs
 usually dimeric or tetrameric

14.  Both classes of aminoacyl-tRNA synthetases
are multidomain proteins.
 An aaRS consists of a catalytic domain (where
both the above reactions take place)
 An anticodon binding domain (which
interacts mostly with the anticodon region of
the tRNA and ensures binding of the correct
tRNA to the amino acid).

16.  First observed by Romanian cell biologist
George Palade(1950) The term "ribosome" was
proposed by scientist Richard B. Roberts in
1958
 Ribosomes are the sites of protein synthesis in
both prokaryotic and eukaryotic cells.
 Ribosomes are made from complexes of RNAs
and proteins called ribonucleoproteins.

17. In bacterial cells, ribosomes are synthesized in the
cytoplasm through the transcription of multiple ribosome
gene operon.
 FREE RIBOSOMES- move about anywhere in the cytosol,
but are excluded from the cell nucleus and other organelles.
 MEMBERANE BOUND RIBOSOMES When a ribosome
begins to synthesize proteins that are needed in some
organelles, the ribosome making this protein can become
"membrane-bound". -

18.  Prokaryotes
 70S ribosomes,
 small (30S) large (50S)
subunit.
 16S RNA subunit 5S RNA ,
23S
 Eukaryotes
 80S ribosomes,
 small (40S) large (60S)
subunit. 18S 5,5.8,28s RNA

20.  The ribosome contains three RNA binding
sites, designated A, P and E.
 The A site binds an aminoacyl-tRNA (a tRNA
bound to an amino acid)
 the P site binds a peptidyl-tRNA (a tRNA
bound to the peptide being synthesized)
 and the E site binds a free tRNA before it exits
the ribosome.
 s

22.  Blueprint of protein reproduction.
 Transcribed from DNA
 mRNA transfers genetic information from the
cell nucleus into the protein-producing
ribosomes located in the cytoplasm.
 Each codon corresponds to a specific amino
acid, and the sequence of codons ends with a
codon that has a stop signal.

23.  It is an immature single strand of messenger
ribonucleic acid (mRNA).
 synthesized from a DNA template in the cell
nucleus by transcription.
 comprises the bulk of heterogeneous nuclear
RNA (hnRNA).
 The term hnRNA is often used as a synonym
for pre-mRNA..

24.  Initiation of translation in prokaryotes involves the
assembly of the components of the translation
system which are:
 the two ribosomal subunits (50S & 30S subunits)
 the mRNA to be translated, the first (formyl)
aminoacyl tRNA (the tRNA charged with the first
amino acid),
 GTP (as a source of energy),
 three initiation factors (IF1, IF2, and IF3) which
help the assembly of the initiation complex.

26.  starts when the fmet-tRNA enters the P site, causing a
conformational change opening the A site for the new
aminoacyl-tRNA to bind.
 binding is facilitated by elongation factor-Tu (EF-Tu),
a small GTPase
 The growing polypeptide connected to the tRNA in
the P site is detached from the tRNA in the P site and a
peptide bond is formed between the last amino acids of
the polypeptide and the amino acid still attached to the
tRNA in the A site.

27.  This process, known as peptide bond formation, is
catalyzed by a ribozyme
 The A site has the newly formed peptide, while the
P site has an uncharged tRNA (tRNA with no
amino acids). The newly formed peptide in the A
site tRNA is known as dipeptide and the whole
assembly is called dipeptidyl-tRNA.

29.  Termination occurs when one of the three termination
codons moves into the A site , recognized by proteins
called release factors namely RF1 (recognizing the
UAA and UAG stop codons) or RF2 (recognizing the
UAA and UGA stop codons).
 These factors trigger the hydrolysis of the ester bond in
peptidyl-tRNA and the release of the newly
synthesized protein from the ribosome.
 A third release factor RF-3 catalyzes the release of RF-1
and RF-2 at the end of the initiation

31.  The initiation factors eIF4E and eIF4G, in association
with eIF4A and eIF4B, then bring the mRNA to the 40S
ribosomal subunit,with eIF4G interacting with eIF3.
 The 40S ribosomal subunit, in association with the
bound methionyl tRNA and elFs, then scans the
mRNA to identify the AUG initiation codon.
 When the AUG codon is reached, eIF5 triggers the
hydrolysis of GTP bound to eIF2. Initiation factors
(including eIF2 bound to GDP) are then released,
 and a 60S subunit binds to the 40S sub- unit to form the
80S initiation complex of eukaryotic cells.

33.  During chain elongation, each additional
amino acid is added to the nascent polypeptide
chain in a three-step microcycle
 positioning the correct aminoacyl-tRNA in the
A site of the ribosome
 forming the peptide bond
 shifting the mRNA by one codon relative to
the ribosome.

35.  the ribosome engages in a process called
translocation:
 spurred by elongation factors, the ribosome
moves three nucleotides in the 3' prime direction
along the mRNA.
 In other words, the ribosome moves so that a new
mRNA codon is accessible in the A site.

38. Termination of elongation is dependent on
eukaryotic release factor.
 A termination codon (e.g., UAA) at the A site
is recognized by a release factor rather than by
a tRNA.
 The result is the release of the completed
polypeptide chain, followed by the dissociation
of tRNA and mRNA from the ribosome.

40.  It is the most essential process for the
conversion of mRNA to protein without which
no gene would be able to code any functional
protein,which forms the basis of many cellular
and metabolic processes.

41.  The translational machinery is the conserved
part , aids in the conversion of the language of
mRNA to the language of functional protein.
This is the most essential event for the proper
coding by genes for the various metabolic and
cellular aspects of body.

42.  The cell: A molecular approach by Cooper –
Hausmann
 Cell and Molecular Biology by Gerald Karp
 Internet source
 www.translationwiki.com
 www.translationsparknotes.com