Final answer:
The student's question pertains to telomerase, which elongates chromosome ends, utilizes an RNA template for telomere replication, and is active mainly in germline and stem cells, making option (D) All of the above the correct answer.
Step-by-step explanation:
The correct answer to the student's question is (D) All of the above. Telomerase is an enzyme complex with several key functions:
- Acts to elongate the end of linear chromosomes, thereby maintaining their integrity during cell division.
- Contains a built-in RNA template for telomere repeats which it uses to add nucleotides to the 3' end of the DNA.
- Is typically active only in germline cells of a multicellular organism, as well as in adult stem cells and some cancer cells.
Telomerase plays a crucial role in chromosome protection and replication by preventing the shortening of telomeres that naturally occurs during cell division. This action is especially important in cells that divide frequently or require maintenance of long-term replicative potential.