Telomeres, Mitosis, and Cancer

For life to exist, the information (genes) must be passed on.

Fig 3.5 The Cell Cycle

Fig 11.7 DNA replication

Mutations are produced via replication errors and/or environmental mutagens

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.

Human Life Cycle 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 lifestyle and lifespan? Pat Monaghan and Mark F. Haussmann TRENDS in Ecology and Evolution Vol 21 pg 47

Telomere length varies in different parts of adults: telomeres - mitosis stomach & blood cells....short- often

muscle & brain……….long- rare

Telomere length varies in different parts of adults: telomeres - mitosis stomach & blood cells....short- often muscle & brain……….long- rare liver & kidney……..short- rare

Telomere length varies in different parts of adults: telomeres - mitosis stomach & 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 old upper 50% of telomere length lower 50% of telomere length proportion surviving % 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 Cycle Fig 3.5

Mitosis: A DNA Perspective

Mitosis plays a role in: Growth and Development Repair and Turnover of Cells Reproduction –Asexual

start of mitosis Fig 3.8

The Mitotic Spindle (micro- tubules) Sister Chromatids A basic look at mitosis Fig 3.7

Mitosis is tightly regulated: checkpoints Fig 22.16

Cell division is regulated by both positive and negative signals. Positive signals start the process of cell division. Negative signals inhibit cell division.

2 proteins, Cyclin and Cdk, control entry into mitosis Fig 22.16

Cdk 2 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 Liver normal 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 Fig 22.17

Tbl 22.9

Cancer Cells Normal Cells

Benign versus Malignant cancer

How do these mutations arise?