Download The Role of Melanin in Tanning

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.



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.
The cell cycle
Dermatologists use the
ABCDE rule:
•
•
•
•
•
Asymmetry
Border
Color
Diameter
Evolving
Signs of Malignant Melanoma
Source: Group Health

Dear 16 Year old me