Question

Which of the following describes a 'gene' correctly?
(A). Genes are located on chromosome
(B). Gene is a discrete particle
(C). Recombination can happen within a gene
(D). One gene can encode more than one polypeptide
Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (A), (B) and (D) only.
• C. (B), (C) and (D) only.
• D. (A), (C) and (D) only.

Hint:

Mendel's "discrete particle" concept has been replaced by the modern molecular understanding of genes as continuous, spliceable DNA segments.
This excludes (B), leading directly to option (D).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Our understanding of the "gene" has evolved from Mendel's initial concept of abstract hereditary factors to our modern understanding of complex, physical molecular segments of DNA.

Step 2: Detailed Explanation:
Let us evaluate each of the statements describing a gene:
(A) is correct because genes are physical segments of DNA arranged linearly along chromosomes.
(B) is incorrect in the context of modern genetics.
While Mendel initially conceptualized genes as abstract "discrete particles" (factors), modern biology shows that genes are integrated segments of continuous double-stranded DNA molecules rather than individual physical particles.
(C) is correct because genetic recombination (crossing over) is not restricted to the regions between genes.
It can occur within the nucleotide sequence of a single gene, a process known as intragenic recombination.
(D) is correct because many eukaryotic genes can produce multiple distinct polypeptide chains from a single primary transcript through alternative splicing of exons.
Therefore, statements (A), (C), and (D) are correct descriptions of a gene.

Step 3: Final Answer:
This combination corresponds to option (D).