AP BIOLOGY

Detailed explanation-1: -The Hayflick Limit is a concept that helps to explain the mechanisms behind cellular aging. The concept states that a normal human cell can only replicate and divide forty to sixty times before it cannot divide anymore, and will break down by programmed cell death or apoptosis.

Detailed explanation-2: -But there is only one eponymous limit in biomedicine: the Hayflick Limit, the number of times (about 50) that normal human embryonic cells can divide before they succumb to senescence.

Detailed explanation-3: -Senescence often occurs when cells in culture have reached their maximum number of divisions, the Hayflick limit, and is often associated with telomere shortening leading to DNA damage due to reduced telomerase activity.

Detailed explanation-4: -Gerontologist Leonard Hayflick at the University of California thinks that humans have a definite expiry date. In 1961, he showed that human skin cells grown under laboratory conditions tend to divide approximately 50 times before becoming senescent, which means no longer able to divide.

Detailed explanation-5: -Telomere length The typical normal human fetal cell will divide between 50 and 70 times before experiencing senescence. As the cell divides, the telomeres on the ends of chromosomes shorten. The Hayflick limit is the limit on cell replication imposed by the shortening of telomeres with each division.