presentation education molecular biology

1. STRUCTURE AND
FUNCTIONS OF tRNA

2. Definition of tRNA- Transfer RNA or tRNA is
a type of RNA molecule that helps to decode
information present in mRNA sequences into
specific proteins.
 tRNA molecule is a carrier of amino acid that brings
appropriate amino acid to ribosome based on the
codon present in mRNA sequence.

3.  tRNA is also known as an adaptor molecule as it
translates the codons present in mRNA sequences
into amino acids.
 tRNA is only 70-90 nucleotides in length, making it
the smallest out of the three main RNAs (mRNA
and rRNA).

4. TYPES OF RNA
 In both prokaryotes and eukaryotes, there are three main
types of RNA.
 messenger RNA (mRNA), ribosomal RNA (rRNA), and
transfer RNA (tRNA).

5. STRUCTURE OF tRNA
 tRNA is the smallest of the 3 types of RNA.
 tRNA being a type of RNA molecule is composed of a ribose sugar,
phosphate and nitrogenous base.
 It is also known as Adapter RNA.
 It is a biopolymer of ribonucleotides.
 It is 10-15% of total RNA.
 Single stranded polynucleotide chain.
 Duplex at complementary bases.
 Clover leaf shape in two dimension.
 Runs from 5 to a 3 end.
 tRNA contains mainly four arms; the acceptor arm, the anticodon arm,
pseudohydrouridine arm, the T arm and the variable arm.

7. The Acceptor arm
 Site of attachment of the amino acid.
 It is formed by the base pairing of 7-9 nucleotides of 5’ terminal
and 3’ terminal.
 Has 3 unpaired nucleotide, CCA.
 The amino acid attaches to the 3’ hydroxyl group of the acceptor
arm.
The Anticodon loop
 Has triplet nucleotide sequence complementary to the codon of the
amino acid which the tRNA carries.
 The sequence is read from 3´ to 5´ direction.

8. D arm
 D arm has a stem of 3-4 base pairs
and it ends in a loop called D loop as
it generally contains dihydrouridine,
a modified nucleotide.
TψC arm
 The T arm consists of a stem of 4-5
bp containing pseudouridine,
modified uridine.
 It helps in the recognition of the
tRNA molecule.

9. Extra arm
 Between pseudouridine and Anticodon arm.
 The most variable feature of trna.
 Variable in size from 3-21 basepairs.
 It helps in the recognition of the tRNA molecule.
 This tRNS’s extra or variable arm is very short so it looks quite different from the other
arms of the molecule.

10. FUNCTIONS OF tRNA
 Trna specifically plays a role in translation of protein synthesis.
 As its names suggests, it transfers amino acids to the ribosome so
they can be put in the correct order to make the required protein.
 tRNA is specific to each amino acid and carries them during the
translation process in the ribosomal subunits.
 tRNA’s also act as adapters in the translation of the genetic
sequence of mRNA into proteins. Thus, they are also called adapter
molecules.