AP BIOLOGY

Detailed explanation-1: -In embryonic stem cells, telomerase is activated and maintains telomere length and cellular immortality; however, the level of telomerase activity is low or absent in the majority of stem cells regardless of their proliferative capacity.

Detailed explanation-2: -Increasing the cell’s concentration of telomerase, such as by exercise and diet as Blackburn’s study found, is thought to lengthen the telomeres, thereby providing the chromosomal stability that is associated with tissue renewal and disease prevention.

Detailed explanation-3: -Telomerase is not usually active in most somatic cells (cells of the body), but it’s active in germ cells (the cells that make sperm and eggs) and some adult stem cells.

Detailed explanation-4: -Telomerase: the key telomere length maintenance mechanism Telomerase is a large ribonucleoprotein complex responsible for progressive synthesis of telomeric DNA repeats (TTAGGG) at the 3′ ends of linear chromosomes, thereby reversing the loss of DNA from each round of replication.

Detailed explanation-5: -Telomerase is found in high levels in germline? cells (egg and sperm) and stem cells. In these cells telomere length is maintained after DNA replication and the cells do not show signs of ageing.