Transcript 5.3 Regulation of the Cell Cycle

5.3 Regulation of the Cell Cycle
KEY CONCEPT
Cell cycle regulation is necessary for healthy
growth.
5.3 Regulation of the Cell Cycle
Objectives
• Identify internal and external factors that regulate cell
division.
• Explain cancer in terms of the cell cycle.
5.3 Regulation of the Cell Cycle
Vocabulary
• Growth Factor
– Broad group of proteins that stimulate cell division.
• Apoptosis
– Programmed cell death.
• Cancer
– Common name for a class of diseases characterized
by uncontrolled cell division.
• Benign
– Having no dangerous effect on health, especially
referring to an abnormal growth of cells that are not
cancerous.
5.3 Regulation of the Cell Cycle
Vocabulary
• Malignant
– Cancerous tumor in which cells break away and
spread to other parts of the body, causing harm to the
organism’s health.
• Metastasize
– To spread by transferring a disease-causing agent
from the site of the disease to other parts of the body.
• Carcinogen
– Substance that produces or promotes the
development of cancer.
5.3 Regulation of the Cell Cycle
Internal and external factors regulate cell division.
• External factors include physical and chemical signals.
• Growth factors are proteins that stimulate cell division.
– Most mammal cells form a single layer in a culture
dish and stop dividing once they touch other cells.
5.3 Regulation of the Cell Cycle
• Two of the most important internal factors are kinases
and cyclins.
• External factors trigger internal factors, which affect the
cell cycle.
5.3 Regulation of the Cell Cycle
• Apoptosis is programmed cell death.
– a normal feature of healthy organisms
– caused by a cell’s production of self-destructive
enzymes
– occurs in
webbed fingers
development
of infants
5.3 Regulation of the Cell Cycle
Cell division is uncontrolled in cancer.
• Cancer cells form disorganized clumps called tumors.
– Benign tumors remain clustered and can be removed.
– Malignant tumors metastasize, or break away, and can
form more tumors.
normal cell
cancer cell
bloodstream
5.3 Regulation of the Cell Cycle
• Cancer cells do not carry out necessary functions.
• Cancer cells come from normal cells with damage to
genes involved in cell-cycle regulation.
5.3 Regulation of the Cell Cycle
• Carcinogens are substances known to promote cancer.
• Standard cancer treatments typically kill both cancerous
and healthy cells.
5.3 Regulation of the Cell Cycle
Question/Answer
• Suppose a child was born whose receptors for growth
hormone did not work properly. How do you think this
would affect the child’s development?
– The ability of the child to produce new cells and
therefore tissues at the proper rate would be affected,
which could affect height and weight, but also
developing tissues and organs.
• HeLa cells are also used to study cell signaling
processes. What might be a disadvantage of using
cancer cells to study processes occurring in healthy
cells?
– Cancer cells are mutants and may not have exactly
the same processes as a healthy cell. This could lead
to errors.