Telomerase

Telomerase is a ribonucleoprotein enzyme that extends chromosome ends by adding repeated DNA sequences, using an internal RNA template.

Telomerase reverse transcriptase: The catalytic protein subunit of telomerase that synthesizes DNA from its RNA template. It carries out the DNA-synthesis reaction that lengthens telomeres.
Chromosome: A DNA molecule packaged with proteins that carries genetic information in a cell. Telomerase acts at the ends of linear chromosomes.
Cancer: A group of diseases in which abnormal cells grow and spread without normal control. Many cancers activate telomerase to maintain telomeres during continued cell division.
Carol W. Greider: An American molecular biologist who shared the 2009 Nobel Prize in Physiology or Medicine for discovering telomerase. Greider identified telomerase while working with Elizabeth Blackburn.
Alternative lengthening of telomeres: A telomerase-independent pathway that lengthens telomeres through DNA recombination-based processes. Some cancers maintain telomeres through this pathway instead of telomerase.
Telomerase RNA component: The RNA subunit of telomerase that provides the template for adding telomeric DNA repeats. Its sequence determines the repeat telomerase adds to chromosome ends.
DNA replication: The cellular process that copies DNA before cell division. Its inability to copy chromosome ends completely creates the substrate for telomerase action.
Stem cell: An undifferentiated cell that can self-renew and produce one or more specialized cell types. Telomerase helps some stem-cell populations preserve chromosome ends as they divide.
Elizabeth Blackburn: An Australian-American molecular biologist who shared the 2009 Nobel Prize for discoveries about telomeres and telomerase. Blackburn’s work on telomere sequences led to the enzyme’s discovery.
Telomere shortening: The progressive loss of telomeric DNA that can occur during repeated cell division. Telomerase counteracts the shortening associated with incomplete end replication.

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