March 5, 2015

By the end of class, I will be able to…  Describe the role of Melanin in tanning.  Explain the difference between malignant and benign tumors and how to tell them apart.

Melanin – the pigment that gives human skin and hair its color. Melanocyte – a cell that makes melanin. Malignant – a mass of abnormal cells; cancerous.

 Benign – a mass of normal cells; NOT cancerous.  Tumor - a swelling of a part of the body caused by an abnormal growth of tissue. Can be benign or malignant.  Cancer – a malignant growth or tumor resulting from the division of abnormal cells.

Sunlight is a type of energy.  It’s Ultraviolet (UV) rays can penetrate human skin.

Why is it so bad for sunlight to penetrate our skin?  The sun’s UV rays penetrate through skin layers and cause mutations in DNA.

 Cells called melanocytes produce the pigment melanin.  Exposure to UV rays cause melanocytes to produce more melanin, further darkening the skin.  Melanin absorbs ultraviolet radiation and defends against further penetration of skin tissue.

 When exposure to UV radiation exceeds the body’s ability to protect the skin with tanning, the radiation causes damage to DNA.  Sometimes this damage affects genes that control how and when the cells grow and divide. If these genes do not work properly, the affected cells may form a cancer.

The cell cycle  Normally, the cell cycle is regulated!  Mutations involve changes in the base sequence of DNA.  During replication, a mutation occurs causing a T-T base pair.

Signs of Malignant Melanoma Source: Group Health Dermatologists use the ABCDE rule: Asymmetry Border Color Diameter Evolving

 Dear 16 Year old me Dear 16 Year old me