What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA:
- A polypeptide of 24 amino acids will be formed
- Two polypeptides of 24 and 25 amino acids will be formed
- A polypeptide of 49 amino acids will be formed
- A polypeptide of 25 amino acids will be formed
The Correct Option is A
Solution and Explanation
If the 25th codon (UAU) in a gene encoding a polypeptide of 50 amino acids is mutated to UAA, the likely outcome is that a polypeptide of 24 amino acids will be formed. The reason for this is that UAA is a stop codon, and when it is encountered during translation, it signals the termination of protein synthesis. Therefore, translation would terminate immediately upon encountering the UAA codon at position 25, resulting in a polypeptide that is 24 amino acids long.
So, the correct option is (A): A polypeptide of 24 amino acids will be formed.
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
Questions Asked in NEET exam
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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Predict the major product $ P $ in the following sequence of reactions:
(i) HBr, benzoyl peroxide
(ii) KCN
(iii) Na(Hg), $C_{2}H_{5}OH$- NEET (UG) - 2025
- Organic Chemistry
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:
- NEET (UG) - 2025
- Electromagnetic Induction and Inductance
- A wire of resistance \(R\) is cut into 8 equal pieces. From these pieces, two equivalent resistances are made by adding four of these together in parallel. Then these two are added in series. The net effective resistance of the combination is:
- 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:
The Molecular Basis of Inheritance
DNA Replication:
DNA synthesis is commenced at particular points within the DNA strand referred to as ‘origins’, which are certain coding regions. There are numerous origin sites, and when replication of DNA starts, these sites are mentioned as replication forks. Within the replication, the complex is the enzyme DNA Helicase, so that they can be utilized as a template for replication. DNA Primase is another enzyme that's essential in DNA replication.
RNA:
Ribonucleic acid (RNA) is an essential biological macromolecule that exists all together in biological cells. It is principally involved in the synthesis of proteins, that carry the messenger instructions from DNA, which itself contains the genetic instructions needed for the event and maintenance of life. In some viruses, RNA, in spite of DNA, carries genetic information.
Genetic Code:
Genetic code is the term we use in the manner that the four bases of DNA--the A, C, G, and Ts--are strung together in a way that the ribosome, the cellular machinery, can read them and switch them into a protein. In the ordering, every three nucleotides during a row count as a triplet and code for one amino alkanoic acid.
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