SNC2D

Cell Growth and Repair Cells of different parts of our body will undergo cell growth and mitosis at different rates Skin cells and cells in the digestive tract undergo mitosis regularly Nerve cells do not undergo mitosis once they mature.

Cell Time Lines Cells in our intestines divide every 3 days Red blood cells divide every 4 months Pancreatic cells divide every year Immune system cells divide every 6 weeks Brain cells last our entire lives

 Cell Death Part 1  Apoptosis is the death of cells that are no longer useful When a cell becomes damaged or undergoes infection, or its DNA becomes damaged somehow, it will self-destruct Once a cell has replicated times, it will undergo the apoptosis process

 Cell Death Part 2  Necrosis is the death of cells due to unexpected and accidental cell damage. Necrosis can take place due to toxins, heat, trauma, lack of oxygen, radiation, lack of blood flow During necrosis, the cell's outer membrane loses its ability to control the flow of liquid into and out of the cell. The cell swells up and eventually bursts, releasing its contents into the surrounding tissue. This causes redness and inflammation.

What Happens When There is an Unbalance between Mitosis and Apoptosis? Too much apoptosis is partly to blame for some diseases such as Alzheimer's, Parkinson's, and Lou Gehrig's. These diseases are known as “neurodegenerative” diseases. Unchecked mitosis can lead to cancer

Werner Syndrome – The Aging Disease Werner Syndrome is a disease that resembles premature aging. The DNA is marked with many mutations. At age 15, this Japanese-American woman looked healthy, but by age 48, she had clearly developed symptoms of Werner syndrome.

What Happens When There IS a healthy balance between Mitosis and Apoptosis? Longest Life – 122 years!!! Jeanne Calment (1875–1997) has lived longer than any other human on record.

Theories for Living a Long Life Studies of centenarians (people who live 100 years or more) said that these factors contribute to a long and healthy life… Positive outlook Healthy eating habits Moderate exercise Close ties to family and friends Genetic factors

When Mitosis Goes Wrong Let’s read page 34 in our textbooks about Cancer Cells

How Cancer Cells are Different Cancer cells do not stop duplicating They do not obey signals from other cells Cancer cells do not specialize Cancer cells can detach and spread to other parts of the body

Facts about Cancer (from WHO) There are more than 100 types of cancers – any part of the body can be affected 13% of deaths worldwide are due to cancer (7.6 million people in 2008) Common types of cancer in men are: lung, stomach, liver, colorectal and oesophagus Common types of cancer in women are: breast, lung, stomach, colorectal and cervical Tobacco use in the single largest preventable cause of cancer – it causes 22% of cancer deaths

Hypothesized Causes of Cancer… Person’s genetic factors Ultraviolet light from the SUN Infections from certain viruses, bacteria and parasites Chemicals such as asbestos, tobacco smoke, aflatoxin (found in contaminated food), arsenic (found in contaminated water) Radiation from medical x-rays Poor diet Air pollution Pesticides (linked to animal cancers) Indoor tanning equipment

1/5 of worldwide cancers are caused by a chronic infection HPV causes cervical cancer Hepatitis B causes liver cancer Cancers can be cured if detected early and treated adequately 30% of cancer can be prevented by not using tobacco, maintaining a healthy diet, being physically active, moderating the use of alcohol, and receiving immunizations for cancer causing infections Facts about Cancer (from WHO)

Video about Cancer Biology ture=related ture=related If this topic interests you, I suggest doing further research on the World Health Organization (WHO) website or International Agency for Research on Cancer (IARC) website