The document discusses the process of translation in three sentences: Translation involves mRNA being read by ribosomes to synthesize a polypeptide based on the mRNA sequence. Amino acids are activated and attached to specific tRNAs, which bring them to the ribosome in the correct order to add to the growing polypeptide chain. The polypeptide may then undergo post-translational modifications before taking on its functional shape.

2. Translation:
 Translation is a second step of central dogma.
 It involves a change in language of nucleotide order in
mRNA molecule to amino acid sequence in
polypeptide.

3. Transcription:
• Transcription in which enzyme RNA polymerase
assemble an mRNA molecule on template DNA stand.
 It nucleotide sequence is complementary to DNA
stand.
Translation:
• Translation in which ribosome assemble a polypeptide
chain whose amino acid sequence is specified by the
nucleotide sequence in mRNA.

5. EXPLAINATION
 Translation started when an rRNA molecule within
ribosome recognizes and binds to initiation codon of
mRNA.
 The ribosome then move along mRNA molecule three
molecules at a time.
 Codon specific tRNA with its amino acid comes to join the
codon on mRNA. This is then transferred into polypeptide
chain keep elongation until ribosome reaches stop codon
which does not code for any amino acid.
 The translation stops and ribosome, polypeptide chain and
mRNA are all set free.

6. Mechanism of Translation
Activation of amino acids
Attachment of activated amino acid with tRNA.
Stages of translation: initiation, elongation and
termination of polypeptide chain.
Modification of released polypeptide chain.

7. Activation of amino acid
 The amino acids in cytoplasm occur in inactive form.
 Hence activated by giving them energy.
 The activation is provided by ATP whose molecule
untie with amino acids forming highly reactive amino
acid phosphate – adenyl complex also known as amino
acyl adenylates.
 The process of activation is governed by specific
enzyme amino acyl tRNA synthetase.

8.  The enzyme amino acyl tRNA synthetase are required
to link amino acid to their cognate tRNA molecules.
 There are twenty different amino acyl TRNA
synthetase in each cell( one of each of 20 amino acid
that take part in protein synthesis).
 But as many as 60 different tRNA molecules are found
in the cell. It means some amino acids have more than
one tRNA and only one amino acyl tRNA synthetase
for all tRNA of amino acid.

10. Attachment of activated amino acid
with tRNA
 The enzyme bond activated amino acid amino acyl
adenylates (AAA) become attached to 3 end of their
respective tRNA molecules.
 The attachment is catalyzed by some enzymes, amino
acyl transfer RNA synthetase that catalyses activation
of their amino acid. The product thus formed is known
as amino acyl transfer RNA complex.

11.  The tRNA charged with its cognate amino acid serve as
an adaptor molecule for decoding the information on
mRNA. There tRNA is also called adaptor RNA.
 The tRNA with its attach amino acid is said to be
acylated or charged tRNA.
 The tRNA molecule without an amino acid is said to
be uncharged tRNA.
 With an incorrect amino acid it is said to be
mischarged tRNA.

12. Stages during Translation
 The process of translation can be separated into
following steps:
• Initiation
• Elongation
• Termination

13. What is eukaryotes?
Eukaryotes are organisms with a complex cell or cells . In
which the genetic material is organized into membrane.
Bound nucleus or nuclei it also contain organelles.

14. Translation – An overview
 Ribosomes translate the genetic message of mRNA into protein
 The mRNA is translated from 5 to 3
 Amino acids bound to tRNAs are in a proper sequence due to
 Specific binding of each amino acid to it’s transfer rna
 specific base Pairing between the messenger. rna codon and transfer RNA
anticodon

15. Components of translation
Mrna: made in the nucleus,. Transported to cytoplasm
Trna: Adoptor molecules that mediate the transfer of information from
nucleic acid to protein
Ribosome: manufacturing unit of cell
Enzymes: required for the attachment of amino acid to correct tRNA
molecules and for the peptide bond formation between amino acids
Protein:. Soluble factor necessary for proper initiation, elongation and
termination

16. Three steps of translation
 Initiation
 Elongation
 Termination
Initiation
The initiation codon is an Aug
Is towords the 5 end of the mRNA molecule that is being translated.
Small subUnIt of ribosome ( + initiation factor . Gtp and tRNA) bind to 5 cap and
scan along the mRNA until the first Aug
Translation start at the first Aug.

17. Elongation
The start of elongation, the mRNA is bound to the complete two subUnIt
ribosome
 With the initiation tRNA in p site
 And a site is free for binding to the next tRNA
The ribosome move along the mRNA in a 5 to 3 direction in a step- wise
process recognizing each subunit codon.
The peptidyl transferase enzyme then catalyzes the formation of a peptide
bond between
 The free N terminal Of the amino acid at the a site.

18.  And the carboxyl end of the amino acid at the p site. Which is actually
connect to the trna
This disconnect trna met from the amino acid and the tRNA at a site now
carries two amino acids
 With a free terminal and the carboxyl terminal of the second amino acid
connected to it’s tRNA.

19. Post Translational Modifications (PTMs):
 Covalent or generally enzymatic modifications of proteins during or after
the synthesis of the proteins.
 Post translational modifications or PTMs are involved in modifying the
protein structure after they have been translated according to
information on the mRNA.
 The post translational modifications can be enzymatic or covalent.
 In the human body these PTMs increases the diversity and accuracy of
proteins.

20. Types of PTMs:
Trimming
Covalent Attachments
Protein Folding
Protein Degradation

21. Trimming:
Insulin is synthesized in the cells and it is in inactive form that it is can’t
perform it’s function. For the proper functioning of insulin its post
translational modifications occurs that have involve the removal of the part
of protein to convert it into a three dimensional and fully active form.

23. Covalent Attachments:
Covalent attachments refers to the addition or the transfer of the
polypeptide chain that acts as an acceptor region. In this way, proteins are
modified for the diversity of function. It includes:
 Phosphorylation
 Glycosylation
 Sulfation
 Methylation
 Hydroxylation

24. Phosphorylation:
 Phosphorylation is the addition of one or more phosphate groups to the
protein. Post Translational Phosphorylation is one of the most common
protein modifications that occur in animal cells. The vast majorities of
phosphorylation occur as a mechanism to regulate the biological activity
of a protein and as such are transient.
 In animal cells Serine, tyrosine and threonine are the amino acids that
subjected to the phosphorylation.

26. Glycosylation:
Glycosylation is the addition of carbohydrate molecules to the polypeptide
chain and modifying it into glycoproteins. Many of the proteins that are
destined to become a part of plasma membrane or to be secreted from the
cell, have carbohydrate chains attached to the amide nitrogen of
asparagine(N linked) or the hydroxyl groups of serine, threonine(O linked).
N glycosylation occurs in ER and O glycosylation occurs in the Golgi
Complex.

28. Sulfation:
Sulfate modification takes place by the addition of sulphate molecules and
these modifications of proteins occurs at tyrosine residues. Tyrosine
sulfation accomplished via the activity of tyrosyl protein sulfotransferases
(TPST) which are membrane associated enzymes of trans-Golgi network.
There are two known TPSTs.
1. TPST-1
2. TPST-2
The universal phosphate donor is 3’-phosphoadenosyl-5’-phosphosulphate
(PSPA).

30. Methylation:
The transfer of one-carbon methyl groups to nitrogen or oxygen to amino
acid side chains increases the hydrophobicity of the protein and can
neutralize a negative amino acid charge when bound to carboxylic acids.
Methylation is mediated by methyl transferases and S-adenosyl methionine
(SAM) is the primary methyl group donor.

32. Hydroxylation:
The biological process of addition of a hydroxy group to a protein amino acid
is called Hydroxylation. Protein hydroxylation is one type of PTM that
involves the conversion of –CH group into –COH group and these
hydroxylated amino acids are involved in the regulation of some important
factors called transcription factors. Among 20, the two amino acids can be
regulated these are proline and lysine.

34. Protein Degradation:
Proteins that are defective for example, misfolded or destined for rapid
turnover are often marked for destruction by ubi ubiquitination-the
attachment of chains of a small, highly conserved protein, called ubiquitin.
Proteins marked in this way are rapidly degraded by a cellular component
known as the proteasome, which is a macromolecular, ATP-dependent,
proteolytic system located in the cytosol.

35. Protein Folding:
Proteins must fold to assume their functional state. Folding can be
spontaneous or facilitated by proteins known as Chaperones.