Question:
(i) How and why is charging of tRNA essential in the process of translation ?
(ii) State the function of ribosome as a catalyst in translation in bacteria.
(iii) Explain the process of binding of ribosomal units to mRNA during protein synthesis.
(iv) Where are untranslated regions located in mRNA ? Mention their role.
(i) How and why is charging of tRNA essential in the process of translation ?
(ii) State the function of ribosome as a catalyst in translation in bacteria.
(iii) Explain the process of binding of ribosomal units to mRNA during protein synthesis.
(iv) Where are untranslated regions located in mRNA ? Mention their role.
Show Hint
Think of aminoacyl-tRNA synthetase, 23S rRNA as ribozyme, small subunit then large subunit at AUG, and UTRs at both ends.
Updated On: Oct 23, 2026
Show Solution
Verified By Collegedunia
Solution and Explanation
Step 1: Charging of tRNA, how it happens:
The amino acid is first activated. The enzyme aminoacyl-tRNA synthetase joins the amino acid to ATP and forms an amino acid-AMP complex.
The activated amino acid is then moved to the \( 3^{\prime} \) (CCA) end of its own tRNA. The product is aminoacyl-tRNA, also called a charged tRNA.
Step 2: Charging of tRNA, why it is essential:
A tRNA cannot carry an amino acid on its own. Without charging, the amino acid would never reach the ribosome.
The anticodon of the charged tRNA pairs with the mRNA codon, so each codon brings in the correct amino acid. The energy stored in the bond also pays for the peptide bond.
Step 3: Ribosome as a catalyst in bacteria:
The 23S rRNA of the large subunit works as a ribozyme. It catalyses the formation of the peptide bond between the amino acids held at the two sites of the large subunit.
Step 4: Binding of the ribosomal units to mRNA:
In the inactive state the ribosome stays as two separate subunits. The small subunit first meets the mRNA and binds near the start codon AUG.
The initiator tRNA (carrying methionine) pairs with AUG. Then the large subunit joins the small subunit and forms the complete ribosome. Translation moves on to elongation.
Step 5: Untranslated regions (UTRs):
UTRs lie on both ends of the mRNA. One is at the \( 5^{\prime} \) end, before the start codon. The other is at the \( 3^{\prime} \) end, after the stop codon.
They are not translated into protein. They are needed for efficient translation.
Final Answer:
All four parts are answered: tRNA charging by aminoacyl-tRNA synthetase, 23S rRNA as the catalyst, small subunit first and then large subunit on AUG, and UTRs at the \( 5^{\prime} \) and \( 3^{\prime} \) ends.
The amino acid is first activated. The enzyme aminoacyl-tRNA synthetase joins the amino acid to ATP and forms an amino acid-AMP complex.
The activated amino acid is then moved to the \( 3^{\prime} \) (CCA) end of its own tRNA. The product is aminoacyl-tRNA, also called a charged tRNA.
Step 2: Charging of tRNA, why it is essential:
A tRNA cannot carry an amino acid on its own. Without charging, the amino acid would never reach the ribosome.
The anticodon of the charged tRNA pairs with the mRNA codon, so each codon brings in the correct amino acid. The energy stored in the bond also pays for the peptide bond.
Step 3: Ribosome as a catalyst in bacteria:
The 23S rRNA of the large subunit works as a ribozyme. It catalyses the formation of the peptide bond between the amino acids held at the two sites of the large subunit.
Step 4: Binding of the ribosomal units to mRNA:
In the inactive state the ribosome stays as two separate subunits. The small subunit first meets the mRNA and binds near the start codon AUG.
The initiator tRNA (carrying methionine) pairs with AUG. Then the large subunit joins the small subunit and forms the complete ribosome. Translation moves on to elongation.
Step 5: Untranslated regions (UTRs):
UTRs lie on both ends of the mRNA. One is at the \( 5^{\prime} \) end, before the start codon. The other is at the \( 3^{\prime} \) end, after the stop codon.
They are not translated into protein. They are needed for efficient translation.
Final Answer:
All four parts are answered: tRNA charging by aminoacyl-tRNA synthetase, 23S rRNA as the catalyst, small subunit first and then large subunit on AUG, and UTRs at the \( 5^{\prime} \) and \( 3^{\prime} \) ends.
Was this answer helpful?
0
0
Top CBSE CLASS XII Biology Questions
- All algae have
- With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
- With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte
- Draw a labeled diagram of male reproductive system.
- Draw a labeled diagram of female reproductive system.
View More Questions
Top CBSE CLASS XII Translation Questions
- Write the initiating codon for translation, its anticodon, and the amino acid it codes for.
- (ii) Write the initiating codon for translation, its anticodon, and the amino acid it codes for.
- (a) Explain the process by which amino acid gets attached to the tRNA molecule during translation process.
(b) How does the translation process get terminated?
(c) Expand ‘UTR’. Where are they located? Select the option that has only termination codons.
When an amino acid is coded by more than one codon, the genetic code is said to be :
Top CBSE CLASS XII Questions
- 2, b, c are in A.P. and the range of determinant $\begin{vmatrix}1&1&1\\ 2&b&c\\ 4&b^{2}&c^{2}\end{vmatrix}$ is [2, 16]. Then find range of c is
- A boy of mass 50 kg is standing at one end of a, boat of length 9 m and mass 400 kg. He runs to the other, end. The distance through which the centre of mass of the boat boy system moves is
- A capillary tube of radius r is dipped inside a large vessel of water. The mass of water raised above water level is M. If the radius of capillary is doubled, the mass of water inside capillary will be
- A circular disc is rotating about its own axis. An external opposing torque 0.02 Nm is applied on the disc by which it comes rest in 5 seconds. The initial angular momentum of disc is
- A circular disc is rotating about its own axis at uniform angular velocity \(\omega.\) The disc is subjected to uniform angular retardation by which its angular velocity is decreased to \(\frac {\omega}{2}\) during 120 rotations. The number of rotations further made by it before coming to rest is
View More Questions