When a gene reaches it’s Hayflick limit, what tells it to stop dividing? Is this coded in part of it’s DNA or is

Question: When a gene reaches it's Hayflick limit, what tells it to stop dividing? Is this coded in part of it's DNA or is there some form of hormone which deals with this?

Asked by cecylia to Michaela on 24 Jun 2010 in Categories: Your Research.
- Michaela Livingstone answered on 24 Jun 2010:
  
  When cells reach their Hayflick limit, their telomeres (which are repeating sequences at the end of every chromosome that are progressively shortened during each replication cycle) become too short (after 40-60 divisions), and functional genes start to be deleted. Cells have machinery in the form of proteins which can detect when telomeres become so short that functional genes are being damaged. At this point the cell stops dividing and enters a phase called Senescence – which is like cellular old age.

Question: When a gene reaches it's Hayflick limit, what tells it to stop dividing? Is this coded in part of it's DNA or is there some form of hormone which deals with this?