Exams › NEET › Biology

In their 1958 experiment, Meselson and Stahl cultured Escherichia coli in a medium containing ammonium chloride with the heavy isotope nitrogen (¹⁵N) for multiple generations to investigate the semi-conservative nature of DNA replication.

1. The central dogma describes the one-way flow of genetic information from DNA to RNA (via transcription) and from RNA to protein (via translation).
2. The genetic code is a triplet code where each codon specifies one amino acid in a protein. There are four nucleotide bases—A, U, G, and C—and since codons are triplets, there are 64 (4×4×4) possible combinations. Out of these, 61 codons code for 20 amino acids, while the remaining three (UAG, UGA, and UAA) are stop codons. Due to this redundancy, multiple codons can code for the same amino acid.
3. Nucleosomes are spherical structures composed of an octamer of histone proteins, consisting of two molecules each of four different types of histones.
4. The genetic code defines the correspondence between the sequence of bases in mRNA and the sequence of amino acids in a protein. It involves the bases adenine, guanine, cytosine, and uracil.

Correct answer: Nucleosomes are spherical structures composed of an octamer of histone proteins, consisting of two molecules each of four different types of histones.

Solution

The question pertains to the semi-conservative replication of DNA, which is unrelated to options A, B, and D. Option C correctly describes nucleosomes, which are relevant to DNA structure and replication studies.

Related NEET Biology questions

• Which of the following is a transcription factor produced by a regulatory gene?
• Which of the following combination is false?
• Which scientist experimentally proved that DNA is the sole genetic material in bacteriophage?
• If the distance between two consecutive base pairs is 0.34 nm and the total number of base pairs of a DNA double helix in a typical mammalian cell is 6.6 × 10⁹ bp, then the length of the DNA is approximately
• Which of the following RNAs should be most abundant in animal cell?
• The final proof for DNA as the genetic material came from the experiments of:

⚔️ Practice NEET Biology free + battle 1v1 →