Which of the following are the salient features of Human Genome project?
(A) The average gene consists of 3000 bases, but sizes vary greatly.
(B) Chromosome 1 has most genes (2968), and the Y has the fewest (231).
(C) The total number of genes is estimated at 30,000- much lower than previous estimates of 80,000 to 1,40,000 genes.
(D) Repetitive sequences are stretches of DNA sequences that are repeated many times, sometimes hundred to thousand times.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B), (C) and (D)
The Human Genome Project (1990-2003) worked out the sequence of all the bases in human DNA. The book lists its salient features, and all four statements are among them.
(A) The average gene consists of 3000 bases, but sizes vary greatly. Correct. Genes differ widely in length. The largest known human gene, dystrophin, has 2.4 million bases.
(B) Chromosome 1 has most genes (2968), and the Y has the fewest (231). Correct. Genes are not spread evenly over the chromosomes. Chromosome 1 carries the most and the small Y chromosome the fewest.
(C) The total number of genes is estimated at 30,000- much lower than previous estimates of 80,000 to 1,40,000 genes. Correct. The project found far fewer genes than scientists had expected. Almost all (99.9 per cent) of the bases are the same in all people.
(D) Repetitive sequences are stretches of DNA sequences that are repeated many times, sometimes hundred to thousand times. Correct. Such repeated sequences make up a very large part of the genome. They are thought to have no direct coding function, but they tell us about the structure, working and evolution of chromosomes.