Hayflick limit

About Hayflick limit:

• It refers to the maximum number of times a cell can divide.
• It's named after scientist Leonard Hayflick, who discovered this phenomenon.
• The limit plays a crucial role in aging and the development of age-related diseases.
• Hayflick found that cells go through three phases.
  • The first is rapid, healthy cell division.
  • In the second phase, mitosis slows. In the third stage, senescence, cells stop dividing entirely.
  • They remain alive for a time after they stop dividing, but sometime after cellular division ends, cells do a particularly disturbing thing: Essentially, they commit suicide.
  • Once a cell reaches the end of its life span, it undergoes a programmed cellular death called apoptosis.
• Hayflick’s discovery got further weight after researchers in the 1970s discovered telomeres.
• Telomeres are repetitive DNA sequences at the very end of these strands, meant to protect the chromosome.
• Crucially, with each cell division, these telomeres get slightly shorter. Eventually, the telomere loss reaches a critical point at which cell division ends.
• That said, while shortening telomeres is related to aging, the exact relationship between telomere length and lifespan remains unclear. 

Q1: What is Mitosis?

It is the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division. Mitosis is generally followed by equal division of the cell's content into two daughter cells that have identical genomes.

Source: Hayflick limit: Why immortality remains out of humans’ reach