Question

Which of the following sequences are repeated in telomeres?

A) CpG>100
B) CT>200(CT)1-4
C) C>1(A/T)1-4
D) AT>10(AT)1-4

Answer 1

Human telomeres consist of a six-base-pair sequence, TTAGGG, repeated 100 to 1000 times, which protects the DNA during cell division. Telomerase maintains these telomere regions by elongating the 3' end of the DNA strand.

Step-by-step explanation:

The repetitive sequences found in human telomeres are represented by the six-base-pair sequence TTAGGG. Telomeres are vital structures at the ends of linear chromosomes, and their primary role is to protect the coding sequences of DNA from being eroded through successive rounds of cell division. The TTAGGG sequence is repeated between 100 to 1000 times in these regions.

The enzyme telomerase plays a crucial role in the maintenance of telomeres, particularly in stem cells and cancer cells. It contains a built-in RNA template which serves as a guide for adding complementary nucleotides to the 3' end of the DNA strand of the telomere, thereby elongating it. This process ensures that the telomeres are sufficiently long to protect the chromosome ends during DNA replication.