Protein synthesis in an animal cell occurs :
- only on the ribosomes present in cytosol
- on ribosomes present in cytoplasm as well as in mitochondria
- only on ribosomes attached to the nuclear envelope and endoplasmic reticulum
- on ribosomes present in the nucleolus as well as in cytoplasm
The Correct Option is B
Solution and Explanation
Ribosomes are sturdy cellular structures found in the cytoplasm, consisting of ribosomal RNA (rRNA) and a specific group of proteins. They can be either freely floating in the cytosol or attached to the surface of the endoplasmic reticulum (ER). The choice of their location depends on the presence of an ER-targeting signal sequence on the protein being synthesized. Consequently, a given ribosome may be bound to the ER while it synthesizes one protein and reside freely in the cytosol when translating another protein.
So, the correct option is (B): on ribosomes present in cytoplasm as well as in mitochondria
Top Questions on Molecular Basis of Inheritance
- Study the items of Column-I and those of Column-II:
Column-I Column-II
(a) RNA polymerase I (i) 18s rRNA
(b) RNA polymerase II (ii) SnRNAs
(c) RNA polymerase III (iii) hnRNA
Choose the option that correctly matches the items of Column-I with those of Column-II:- CBSE CLASS XII - 2025
- Biology
- Molecular Basis of Inheritance
- The RNA triplet UAG acts as a stop codon which terminates the synthesis of a polypeptide. Below is given a strand of DNA which codes for four amino acids.
In which position will an insertion of a thymine nucleotide result in the termination of translation?
DNA strand:
3′ T C C A C C C G A T G C 5′- CBSE CLASS XII - 2025
- Biology
- Molecular Basis of Inheritance
Construct and label a transcription unit from which the RNA segment given below has been transcribed. Write the complete name of the enzyme that transcribed this RNA.
- CBSE CLASS XII - 2025
- Biology
- Molecular Basis of Inheritance
- The base sequence in one of the strands of DNA is: ‘TAGCATGAT’
- Give the base sequence of its complementary strand.
- How are these base pairs held together in DNA molecule?
- Explain the base complementarity rule. Name the scientist who framed this rule.
- CBSE CLASS XII - 2025
- Biology
- Molecular Basis of Inheritance
Student to attempt either option-(A) or (B):
(A) Write the features a molecule should have to act as a genetic material. In the light of the above features, evaluate and justify the suitability of the molecule that is preferred as an ideal genetic material.
OR
(B) Differentiate between the following:- [(i)] Polygenic Inheritance and Pleiotropy
- [(ii)] Dominance, Codominance and Incomplete dominance
- CBSE CLASS XII - 2025
- Biology
- Molecular Basis of Inheritance
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A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is :
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AB is a part of an electrical circuit (see figure). The potential difference \(V_A - V_B\), at the instant when current \(i = 2\) A and is increasing at a rate of 1 amp/second is:
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- NEET (UG) - 2025
- Resistance
- Consider the diameter of a spherical object being measured with the help of a Vernier Callipers. Suppose its 10 Vernier Scale Divisions (V.S.D.) are equal to its 9 Main Scale Divisions (M.S.D.). The least count in the M.S. is 0.1 cm and the zero of V.S. is at -0.1 cm when the jaws of Vernier callipers are closed. If the main scale reading for the diameter is \(M = 5\) cm and the number of coinciding vernier division is 8, the measured diameter after zero error correction, is:
- NEET (UG) - 2025
- Measurement of length
Concepts Used:
Translation
The translation is the process of converting nucleic acid information into amino acids. It also relates to the process of producing proteins from mRNA templates.
Components of Translation:
The main components of translation include :
- mRNA of both Eukaryotes and Prokaryotes
- tRNA - It helps in sending commands or transferring the information between protein and nucleic acids.
- Ribosomes - It contains ribosomal RNA and proteins, therefore, it is called the manufacturing unit of a cell.
- Enzymes - It is required for the formation of a peptide bond between the amino acids and also to attach amino acids to the accurate tRNA molecules.
- Proteins - They are the soluble factors, which are required for proper initiation, elongation and termination of translation.
Translation Process:
The three stages of translation are-
- Initiation involves assembling ribosomes around mRNA and activating amino acid and delivering it to the transfer RNA.
- Elongation is the process in which the RNA strand gets longer by adding amino acids.
- The termination process only involves releasing a polypeptide chain.