6.6

Question 1

Telomere Function

Answer 1

• Prevents chromsomoes from fusing to one another
• Prevents DA degration
• Assist DNA repair mechinisms
• Determine number of times a cell can divide

Question 2

Role of telomere during replication

Answer 2

• Chromosomes must be capped by telomeres, b/c DNA may be lost every division
• Instead of ‘coding DNA’, portions of telomeres are lost, ~100bp / replication
• Cell senescence
• A period of time when telomeres are completely lost
• Cell may lose it’s ability to grow, metabolize or divide
• May account for loss of certain functions as an individual ages
  ex. hearing, sight

Hayflick Limit
* The total number of times a cell can divide
* Human cells can divide ~50 times before telomeres become too short

• Length of telomeres are not necessarily related to how long individual species live
• Ex. A mouse’s telomeres are longer than a human’s

Question 3

Telomerase

Answer 3

Germ line cells MUST maintain
their genetic integrity
* They cannot tolerate any loss of
genetic material

• Telomerase adds more DNA to
  the shortening telomeres,
  continually restoring their length
• Stem cells and WBC also show the
  presence of telomerase

Question 4

Telomers and Aging

Answer 4

• • Once a cell reaches its Hayflick limit
    and senescence begins, the cell’s
    functioning begins to decline
• As an organism ages, more of its cells reach senescence
• Decreased rate of telomeres shortening shown in individuals who exercise and carry a healthy lifestyle

Question 5

Telomeres
and Cancer

Answer 5

• Cancer cells never stop dividing
• Their telomeres don’t shorten, thus
  there is no cell senescence, b/c they
  produce telomerase in GREAT
  quantities
• Effectively makes cancer cells
  immortal
• New cancer therapies target and
  inhibit the production of telomerase