Cell Division and Cancer

CB 5.25 Genes are the parts of DNA that contain information. Protein

For life to exist, the information (genes) must be passed on. {Mitosis: producing more cells} {Meiosis: producing gametes} CB 13.5

Mitosis

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

The Cell Cycle [DNA Replication] CB 12.5

Complementary base pairs suggest how DNA replication may occur CB 16.9

DNA replication: each strand serves as a template for making a complementary copy O.R. Origin of Replication CB 16.12b

O.R. DNA replication: each strand serves as a template for making a complementary copy CB 16.12b

The two strands of DNA are unwound. DNA replication: each strand serves as a template for making a complementary copy CB 16.12b

The DNA is copied by DNA polymerase (a protein). DNA replication: each strand serves as a template for making a complementary copy CB 16.12b

More unwinding, more copying DNA replication: each strand serves as a template for making a complementary copy CB 16.12b

The DNA has now been copied. There are now two double-stranded DNAs DNA replication: each strand serves as a template for making a complementary copy CB 16.12b

Most DNA has multiple origins of replication CB 16.12b

DNA replication: each strand serves as a template for producing a complementary copy CB 5.28

Sometimes errors are made.

Luckily, errors can be repaired. Error

DNA Repair CB Damage or replication error Mismatch removed by enzymes DNA replaced Repair complete

Is recognized as NEW and mismatches are repaired

Not all errors get repaired. These are mutations.

3,000,000,000 (3 billion) base pairs/human cell with 1 error/1 billion base pairs not repaired = (average) ~6 errors each time DNA is replicated Errors are made during DNA replication

Only mutations in gametes will be passed on.

Mutations can be lethal, or can lead to cancer.

Cancer: Cell Division Gone Wrong

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.

Tumors in a Liver normal tumors

Multiple mutations are required for a single cell to become cancerous. CB 18.22

How can mutations be minimized?

Telomeres are non-gene DNA at the ends of DNA strands.

Telomeres are shortened during DNA replication.

Telomeres are non-gene DNA at the ends of DNA strands. Telomeres are shortened during DNA replication, and also by DNA damage.

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

Why not produce telomerase all of the time? 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 an indirect measure of mutations.

Fig. 3 TRENDS in Ecology and Evolution Vol 21 pg 47 Balance between Longevity and Health

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

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

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?

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.

Fig. 3 TRENDS in Ecology and Evolution Vol 21 pg 47 Balance between Longevity and Health

How do these mutations arise? CB 18.22

Next: more Cell Division and Cancer