Cell Division Class Notes
1/17
- purpose of cell division: to ensure growth and repair
| [[Mitosis[[ | <<Both<< | {{Meiosis{{ |
|---|---|---|
| One cell becoming many | both make new cells | makes sex cells |
| makes a human cell with 46 chromosomes | occurs in plants & animals | makes a human cell with 32 chromosomes |
| daughter cells are identical | similar steps | happens in plants, animals, and fungi |
| happens in all organisms | cells replicate DNA | two cell divisions, one right after the other |
Cell Cycle Stages
- ^^GAP 1 phase: cell grows; copies organelles^^
- ^^Synthesis: Unzip the nucleus and take the DNA out in the open and copy it^^
- ^^GAP 2: grows more^^
- Mitosis: separates and makes 2 identical cells: separation called cytokinesis
1. Mitosis can only happen if the cell is big enough & the DNA isn’t damaged in any way
- Checkpoints are like a stop sign: makes the cells check if they did everything correctly (cancer cells ignore these checkpoints)
- ^^interphase^^
| CELL TYPE | APPROXIMATE LIFE SPAN |
|---|---|
| skin cell | 2 weeks |
| red blood cell | 4 months |
| liver cells | 300-500 days |
| intestine - internal lining | 4-5 days |
| intestine - muscle and other tissues | 16 years |
- remember SA:V ratio - helps cells maximize material exchange
1/23
- You have to prepare for cell division
- DNA is wrapped around histone to condense it * See test Qs for more info
- Chromatid, Chromosome, Chromatin, Telomeres * DNA wrapped around histone = Chromatin * Chromatid = half of Chromatin * Telomere = protects DNA, has no genes || as cells divide, telomeres get smaller as you age
- apoptosis - death of a cell
- 23rd pair of chromosomes in sex cells matters!! Boy - XY Girl - XX
- DIFFERENCE BETWEEN MITOSIS AND MEIOSIS * Mitosis makes GENETICALLY IDENTICAL cells * meiosis has to do with sex cells
- prophase - chromosomes are condensed! __p__reparation
- metaphase - chromosomes line up in the __m__iddle!
- anaphase - chromosomes split __a__part
- telophase - __t__wo nuclei form on opposite sides of the cell, this protects the DNA
- cytokinesis - cells split into 2 identical cells
Test Qs (so far)
1. When would a cell go into GAP0? - If a cell didn’t produce enough ATP or the mitochondria cells don’t work 2. What is the role of a histone in mitosis? - Condense and organize DNA 3. What would happen if the histones were broken? - DNA will be unravelled, unorganized and cause mutations 4. Know what chromatid____, chromosome____, and chromatids are 5. What is a centromere? - Holds the Chromatin together 6. Identify the part ^^^ Centromere 7. The part of the chromosome that protects DNA but doesn’t contain DNA is the telomere 8. G1 9. S
- G2
- (PMAT) 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase
- What step would a chromosome get left behind? - Anaphase
- FRQ #2
1. What is cancer? - Unregulated cell division 2. checkpoints - where we check for mistakes in the cycle 3. P53 Protein - like a police officer, supervise and police cell cycle (especially checkpoint G1)
1. Repair 2. Apoptosis (G0)
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