| A | B |
|---|
| Why does a cell need to divide? | It cannot perform its functions efficiently if it gets too large |
| cell life cycle | includes interphase and mitosis |
| interphase | about 94% of the cell's life is spent in this phase |
| mitosis | about 6% of the cell's life is spent in this phase |
| stages of interphase | Gap 1 (G1), Synthesis (S), and Gap 2 (G2) |
| stages of mitosis | Prophase, Metaphase, Anaphase, Telophase, Cytokinesis |
| Gap 1 (G1) | stage when most cell growth, organelle replication, and cell activity occurs |
| Synthesis (S) | stage when the cell's DNA is copied inside the nucleus |
| Gap 2 (G2) | stage when the cell makes final preparations and checks for errors in DNA for the next stage (mitosis) |
| Prophase | chromosomes become visible in the center of the cell, and centrioles form the microtubules (spindles) that will eventually guide chromosome division |
| Metaphase | chromosomes line up down the middle of the center of the cell, and spindle fibers attach to the centromeres on each set of sister chromatids |
| Anaphase | centromeres split, and sister chromatids split apart as the spindles start to pull chromosomes to opposite ends of the cell |
| Telophase | spindle fibers break apart, and a nuclear membrane begins to develop and surround each cluster of chromosomes at opposite ends of the cell. The nucleolus also reappears. |
| Chromatin | DNA in the form of strands, gathered up like a ball of yarn in the cell's nucleus |
| longest phase of mitosis | Prophase (approx. 50%) |
| chromatid | one of the two identical copies of DNA that when with its matching "twin", will make "sister chromatids" |
| sister chromatids | set of identical chromatids, attached together by a centromere |
| chromosome | DNA that has been condensed, by being wrapped up around histones, and coiled up tightly to become thicker and shorter during M phase. |
| centromere | the region on a chromosome that joins two sister chromatids |
| cyclin | a protein that regulates a cell's life cycle |
| cancerous cells | cells that grow and divide out of control |
| metastatic cells | cancerous cells that can travel through the blood stream and lymph vessels from one part of the body to another, infecting new areas with cancerous cells |
| Cytokinesis | The cell membrane closes inward splitting the cell into two daughter cells. Daughter cells are genetically identical. |
| the uncontrolled growth of abnormal cells in the body | What is cancer? |
| carcinogen | a substance known to be directly involved in causing cancer |
| mutations | errors that can occur in DNA that can lead to cancerous cells |
| chemotherapy | the use of chemicals to try and stop cancerous cells from growing |
| 15 hours | the length of most cell cycles in the human body |
| stem cell | A cell that is able to develop into any type of cell found in a particular organism |
| a differentiated cell | a cell has become different from the embryonic cell that produced it |
| differentiation | the process by which cells become specialized |
| approximately 100 trillion | the number of cells in the human body |
