Question

Which of the following statements regarding 'human genome' is incorrect?

• A. Human genome consists of $3 \times 10^{9}\,bp$ and about $20,500$ genes
• B. The average gene size is $3000 \,bp$ and dystrophin is the largest known human gene
• C. Chromosome $1$ contains maximum $(2958)$ number of genes and $Y$-chromosome has the least $(231)$ number of genes
• D. Repeated (or repetitive) sequences are not present in human genome

Answer 1

Answer: (D)

Repeated or repetitive sequences make up a large portion of human genome. Repetitive sequences are nucleotide sequences that are repeated many times, sometimes hundred to thousand times. They have no direct coding function but provide information as to chromosome structure, dynamics and evolution. Approximately $1$ million copies of short $5-8$ base pair repeated sequences are clustered around centromeres and near the ends of chromosomes. They represent junk $DNA$.