The enzyme telomerase is part protein and part RNA. What would be the most likely effect of a large deletion in the gene that encodes the RNA part of telomerase, and how would the function of telomerase be affected?

The correct answers are:

The telomerase enzyme will not be able to associate with the telomeres properly. The enzyme will lose the ability to synthesise new telomeric sequence in order to extend the telomeres.

Explanation:

Telomeres can be defined as the highly repetitive sequences of DNA (Deoxyribonucleic Acid) that are located at the end terminal of the linear chromosomes in eukaryotic organisms. These sequences are required to protect the chromosome ends from undergoing recombination or fusion with other chromosomes. The telomeres are synthesised by an enzyme called Telomerase. The enzyme comprises of an RNA (Ribonucleic Acid) sequence and a protein region. The protein functions as a terminal polymerase that operates like a Reverse Transcriptase (synthesises DNA from RNA). The RNA sequence of the telomerase base pairs with the complementary 3' flanking region present in the telomere of the chromosome and extends the DNA sequence in the chromosome complementary to the RNA sequence in the telomerase. This process is repeated to generate an extended 3' terminal of the DNA sequence in the telomere region of the chromosome. The sequence complementary to this extended 3' terminal in the other DNA strand is then synthesised by the DNA polymerase. Absence of the RNA sequence in the telomerase enzyme will prevent its association with the 3' flanking end in the telomere region of the chromosome. Hence, this will prevent the synthesis of any telomeric sequence.