T2M3
● Translational Requirements
○ tRNA
■ tRNA transfers cytoplasmically situated amino acids to a growing
polypeptide strand in a Ribosome
■ Each tRNA contains
● Single RNA strand
● 70-90 nucleotide length
● A lot of complementarity along the tRNA
○ Many structures have hydrogen bonds
○ Makes the helical segments and 3 loops
○
○ Anticodon region:
■ Nucleotide triplet that forms complementary
base pairs with a mRNA codon
■ Written: 3’ - 5’ direction
■ Align with mRNA in a 5’ - 3’ direction
■ At the 3’ end of the tRNA
● Protruding amino acid attachment site
● Single stranded CCA nucleotide
,■ Terminal A (Adenine) is the actual point of
attachment for an amino acid
● tRNA molecule activation
■
■ Activation of a tRNA with a specific amino acid
is carried out by the enzyme - Aminoacyl tRNA
Synthetase
● Specific to tRNA and the Amino acid to
which it’ll bind
● The Active site:
○ Recognizes the Anticodon end of
the tRNA and the region of the
amino acid attachment site
● Processes the Covalent attachment of
tRNA to Amino Acid
○ Energy from ATP
○ Leads to charged tRNA molecule
or Aminoacyl tRNA released
from the enzyme
● Only 45 tRNA molecules
, ○ Some tRNA molecules may be
able to bind to more than one
Codon
○ Largely due to the chemical
nature of the Codon
○ While the first 5’ end of the
mRNA (codon) and the 3’ end of
the tRNA (anticodon) need to be
exact, there is more flexibility for
the 3’ end of the mRNA and the
5’ end of the tRNA
○ Known as Wobble
● Translation occurs in the Cytosol
● Process of Translation
○ Eukaryotes
■
■ Occurs when a translation initiation complex forms towards the 5’ cap
of the mRNA
■ Scans mRNA until AUG is encountered
■ Start of translation:
● Initiation factors will bind to the 5’ cap of the mRNA
, ● Allows for recruitment of the small ribosomal subunit
● Other initiation factors will bind to the tRNA with a charged
methionine
● Move along the mRNA from 5’ - 3’
○ Until AUG
● The large subunit is able to bind to the rest of the initiation
complex
○ From GTP hydrolysis
● Next charged molecule can join the ribosome
● Initiation factors are released
● Polypeptides are synthesised from the Amino end to the
carboxyl end
●
● Methionine will be placed in the Peptidyl (P site) of the
ribosome
● Each subsequent tRNA binds with the Aminoacyl (A site) of
the Large Ribosomal Subunit
● Each tRNA comes with a GTP bound elongation factor
● When the correct Codon-Anticodon pairing is made
○ GTP hydrolysis happens
● Translational Requirements
○ tRNA
■ tRNA transfers cytoplasmically situated amino acids to a growing
polypeptide strand in a Ribosome
■ Each tRNA contains
● Single RNA strand
● 70-90 nucleotide length
● A lot of complementarity along the tRNA
○ Many structures have hydrogen bonds
○ Makes the helical segments and 3 loops
○
○ Anticodon region:
■ Nucleotide triplet that forms complementary
base pairs with a mRNA codon
■ Written: 3’ - 5’ direction
■ Align with mRNA in a 5’ - 3’ direction
■ At the 3’ end of the tRNA
● Protruding amino acid attachment site
● Single stranded CCA nucleotide
,■ Terminal A (Adenine) is the actual point of
attachment for an amino acid
● tRNA molecule activation
■
■ Activation of a tRNA with a specific amino acid
is carried out by the enzyme - Aminoacyl tRNA
Synthetase
● Specific to tRNA and the Amino acid to
which it’ll bind
● The Active site:
○ Recognizes the Anticodon end of
the tRNA and the region of the
amino acid attachment site
● Processes the Covalent attachment of
tRNA to Amino Acid
○ Energy from ATP
○ Leads to charged tRNA molecule
or Aminoacyl tRNA released
from the enzyme
● Only 45 tRNA molecules
, ○ Some tRNA molecules may be
able to bind to more than one
Codon
○ Largely due to the chemical
nature of the Codon
○ While the first 5’ end of the
mRNA (codon) and the 3’ end of
the tRNA (anticodon) need to be
exact, there is more flexibility for
the 3’ end of the mRNA and the
5’ end of the tRNA
○ Known as Wobble
● Translation occurs in the Cytosol
● Process of Translation
○ Eukaryotes
■
■ Occurs when a translation initiation complex forms towards the 5’ cap
of the mRNA
■ Scans mRNA until AUG is encountered
■ Start of translation:
● Initiation factors will bind to the 5’ cap of the mRNA
, ● Allows for recruitment of the small ribosomal subunit
● Other initiation factors will bind to the tRNA with a charged
methionine
● Move along the mRNA from 5’ - 3’
○ Until AUG
● The large subunit is able to bind to the rest of the initiation
complex
○ From GTP hydrolysis
● Next charged molecule can join the ribosome
● Initiation factors are released
● Polypeptides are synthesised from the Amino end to the
carboxyl end
●
● Methionine will be placed in the Peptidyl (P site) of the
ribosome
● Each subsequent tRNA binds with the Aminoacyl (A site) of
the Large Ribosomal Subunit
● Each tRNA comes with a GTP bound elongation factor
● When the correct Codon-Anticodon pairing is made
○ GTP hydrolysis happens
