Transcript 5.3 Regulation of the Cell Cycle TEKS 5A, 5B, 5C, 5D, 9C Cancer cells

5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
The student is expected to:
5A describe the stages of
the cell cycle, including
deoxyribonucleic acid (DNA)
replication and mitosis, and the
importance of the cell cycle to the
growth of organisms;
5B examine specialized cells,
including roots, stems, and leaves of
plants; and animal cells such as
blood, muscle, and epithelium;
5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
(Continued)
5C describe the roles of DNA,
ribonucleic acid (RNA), and
environmental factors in cell
differentiation;
5D recognize that disruptions of
the cell cycle lead to diseases
such as cancer;
9C identify and investigate the role of
enzymes
5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
KEY CONCEPT
Cell cycle regulation is necessary for healthy
growth.
5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
• Two of the most important internal factors are kinases
and cyclins.
• External factors trigger internal factors, which affect the
cell cycle.
Kinases change the activity of other molecules by
adding a phosphate group.
Cyclins are rapidly made and destroyed at different
points in the cell cycle.
5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
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
TEKS 5A, 5B, 5C, 5D, 9C
• Carcinogens are substances known to promote cancer.
• Standard cancer treatments typically kill both cancerous
and healthy cells.
5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
Carcinogens
• Substances that produce or promote the development of
cancer
• Examples: tobacco smoke, air pollutants, radiation, and
even some mutated genes carried by viruses.
5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
Cancer cells
• Characterized by uncontrolled cell division; continue to
grow despite cell-cell contact or lack of growth.
5.3
Regulation of the Cell Cycle
TEKS 5A, 5B, 5C, 5D, 9C
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
TEKS 5A, 5B, 5C, 5D, 9C
• 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
TEKS 5A, 5B, 5C, 5D, 9C
• 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