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Telomeres, Mitosis, and Cancer
Telomeres, Mitosis, and Cancer
For life to exist, the information (genes) must be passed on.
Fig 3.5
The Cell Cycle
Fig 11.7DNA replication
Mutations are produced via replication errors and/or environmental mutagens
Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are non-gene DNA at the ends of DNA strands.
Short telomeres will cause cells to stop replicating or cell death.
The critical size is unknown.
HumanLifeCycle high levels of
telomerase
very little telomerase
Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are shortened during DNA replication, and by DNA damage.
Short telomeres will cause cell senescence or cell death.Telomere size is a measure of mutations.
Do telomere dynamics link lifestyleand lifespan?
Pat Monaghan and Mark F. HaussmannTRENDS in Ecology and Evolution
Vol 21 pg 47
Telomere length varies in different parts of adults:
telomeres - mitosisstomach &blood cells....short - often
Telomere length varies in different parts of adults:
telomeres - mitosisstomach &blood cells....short - often
muscle &brain……….long - rare
Telomere length varies in different parts of adults:
telomeres - mitosisstomach &blood cells....short - often
muscle &brain……….long - rare
liver &kidney……..short - rare
Telomere length varies in different parts of adults:
telomeres - mitosisstomach &blood cells....short - often
muscle &brain……….long - rare
liver &kidney……..short - rare
gametes……long
Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are more sensitive to DNA damage, and may act as a sensor for overall DNA damage levels in a cell.
Does telomere length indicate longevity?
Zebra finch
Telomere length in red blood cells of different birds
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47
Age (years)
common tern
Telomere length in red blood cells of different birds
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47
Age (years)
albatross
TRENDS in Ecology and Evolution Vol 21 pg 47
Telomere length in red blood cells of different birds
Leach’s storm petrel
Telomere length in red blood cells of different birds
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47
Zebra finch
Leach’s storm petrel
common tern
albatross
Telomere length in red blood cells of different birds, different species have different patterns of telomere length and age
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47
Fig. 2 TRENDS in Ecology and Evolution Vol 21 pg 47
Telomere length in white blood cells of different aged people. Telomere length
generally declines, but there is wide variability
THE LANCET • Vol 361 • pg 393
Telomere length and mortality in people over 60 years oldupper 50% of telomere length
lower 50% of telomere length
prop
ortio
n su
rviv
ing
%
years after initial assessment
Telomere length may indicate biological age.
Early stress may cause premature telomere degradation.
For life to exist, the information (genes) must be passed on.
{Mitosis:producing more cells}
{Meiosis:producing gametes}
The Cell CycleFig 3.5
Mitosis:A DNAPerspective
Mitosis plays a role in:• Growth and Development• Repair and Turnover of Cells• Reproduction
–Asexual
startofmitosis
Fig 3.8
TheMitoticSpindle(micro-tubules)
SisterChromatids
A basic look at mitosisFig 3.7
Mitosis is tightly regulated: checkpoints
Fig 22.16
Cell division is regulated by bothpositive and negative signals.
Positive signals start the processof cell division.
Negative signals inhibit cell division.
2 proteins, Cyclin and Cdk, control entry into mitosis
Fig22.16
Cdk2 proteins, Cyclin and Cdk, control entry into mitosis.
Fig 22.16
Fig. 3 TRENDS in Ecology and Evolution Vol 21 pg 47
Balance between Longevity and Health
Mutations
Cancer: Cell Division Gone Wrong
Normal Mammalian Cells Have Contact Inhibition
Cancer Cells Do Not Have Contact Inhibition
Tumors in a Livernormal
tumors
Cancer:
• is the loss of control over cell division.
• Tumors are normal cells that are dividing inappropriately.
– They stop performing their “normal” function, and are dividing repeatedly.
A cell becomes cancerous when there are incorrect positive AND negative
signals.
GO! STOP!
cancer
Multiple mutations are required for cancer to occur
Fig22.17
Tbl 22.9
Tbl 22.9
Cancer Cells
Normal Cells
Benign versus Malignant cancer
How do these mutations arise?
