Transcript Control of the Cell Cycle

Control of the Cell
Cycle
Cancer
Objectives
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Why do some types of cells divide rapidly,
while others divide slowly?
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What tells a cell when it is time to leave one
part of the cell cycle and begin the next?
Proteins and enzymes control cell
cycle
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What controls the cell cycle:
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Cyclins (protein) and a set of enzymes that
attach to the cyclin and become activated
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The interaction of these molecules based on the
conditions in and out of the cell, control the cell
cycle
Enzyme Production
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Directed by genes on the chromosomes
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What is a gene?
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Segment of DNA that controls the production of
protein
Many studies point to the portion of
interphase just before DNA replication as
the key control period in the cell cycle
What causes cancer?
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Occasionally, cells lose control of the cell
cycle
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What causes them to lose control?
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Failure of cell to produce certain enzymes
Overproduction of enzymes
Production of enzymes at the wrong time
Environmental factors
Cancer – malignant growth resulting from
uncontrolled cell division
Lung Cancer
Cancer
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Is caused by a mistake in the cell cycle
Currently, scientists consider cancer to be a
result of changes in one or more of the
genes that produce substances involved in
controlling the cell cycle.
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Changes are expressed as cancer when
something prompts the damaged genes into
action
Cancer
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Cancerous cells form masses of tissue
called tumors that deprive normal cells of
nutrients.
In later stages, cancer cells enter the
circulatory system and spread throughout
the body (metastasis)
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Form new tumors that disrupt the function of
organs, organ systems and ultimately the
organism
Cancer
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2nd leading cause of death in the US,
exceeded only by heart disease
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Can affect any tissue in the body
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Most prevalent cancers in the US: lung,
colon, breast and prostate
Causes of Cancer
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Involve both genetic and environmental factors
Different cancers are more prevalent in different
parts of the world
Environmental
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Cigarette smoke, air and water pollution, exposure to UV
rays from the sun
Genetic
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Viral infections that damage the genes
Carrier of gene that makes you at higher risk (breast
cancer: BRCA1, BRCA2 gene)
Cancer Prevention
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Scientists have established a clear link between a healthy lifestyle
and the incidence of cancer
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Diets low in fat and high in fiber
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Diets high in fat are linked to increased risk of breast, colon and prostate
cancers
People who limit fat intake reduce their risk and also maintain a healthy
body weight
High fiber diets linked to a reduced risk of colon cancer
 Fruits, vegetables and grains = high fiber content
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Vitamins and minerals may also help to prevent cancer
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Keys in this category: caratenoids, Vit A, C & E, calcium
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Caratenoids and Vit A yellow & orange vegetables, and green leafy vegetables
Vitamin C  citrus fruits
Vitamin E  SUN
Calcium  dairy products
Making healthy choices, exercising and avoiding carcinogens help to
reduce your risk for cancer