Cell Cycle, Growth, and Repair - Anatomy and Physiology
- During which phase of the cell cycle is DNA replicated?
- S phase (synthesis).
- What is G0?
- A resting state outside the active cell cycle in which cells carry out normal functions but do not prepare to divide.
- How does regeneration differ from fibrosis in tissue repair?
- Regeneration replaces damaged cells with the same tissue type; fibrosis replaces them with collagen-rich scar tissue.
- What are the three phases of interphase, in order?
- G1, S, and G2.
- Which two families of proteins drive a cell through the cell-cycle checkpoints?
- Cyclins and cyclin-dependent kinases (CDKs), which are active only when bound together.
- Hepatocytes normally rest in G0 but re-enter the cell cycle after part of the liver is removed. What category of cells is this?
- Stable (quiescent) cells, which divide when stimulated by injury or tissue loss.
- During which mitotic phase do chromosomes line up along the cell's equator?
- Metaphase, at the metaphase plate.
- During which mitotic phase do sister chromatids separate and move to opposite poles?
- Anaphase.
- Which category describes cells, such as most neurons and cardiac muscle cells, that rarely or never divide in adults?
- Permanent (nondividing) cells. Damage to these tissues is repaired mainly by scar tissue.
- What are labile cells?
- Cells that divide continuously throughout life, such as epidermal cells and the epithelium lining the gut.
- What does the p53 protein do when DNA is damaged?
- It halts the cell cycle (mainly at G1) to allow repair, or triggers apoptosis if the damage cannot be repaired.
- How does apoptosis differ from necrosis?
- Apoptosis is programmed, orderly cell death without inflammation; necrosis is uncontrolled death from injury that releases contents and causes inflammation.