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. 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. External factors trigger internal factors, which affect 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. cancer cell bloodstream normal cell –Benign tumors remain clustered and can be removed. –Malignant tumors metastasize, or break away, and can form more tumors.

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 –a normal feature of healthy organisms –caused by a cell’s production of self-destructive enzymes –occurs in development of infants webbed fingers Apoptosis is programmed cell death.