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Mitosis and
Asexual Reproduction
I. The Cell CycleA. Why Cells Divide...
1. cells obtain most resources through diffusion
a. diffusion = FAST small distances
b. diffusion = SLOW over long distances
I. The Cell CycleA. Why Cells Divide...
2. Surface Area to Volume ratio (SA : V)
a. small cells = efficient diffusion
1. membrane is big enough to allow enough materials
through
I. The Cell CycleA. Why Cells Divide...
2. Surface Area to Volume ratio (SA : V)
b. as cell grows, V increases FASTER than SA.
1. diffusion distance increases
2. diffusion efficiency decreases
Surface Area to Volume Ratio
I. The Cell CycleA. Why Cells Divide...
2. Surface Area to Volume ratio
*growth is a requirement for most cells – so how do they solve this problem?
c. cells divide in order to keep from getting too large.
- also happen to make clones of themselves in the process
I. The Cell CycleB. The Cell Cycle
1. Interphase (90% of time)
a. normal functions (making proteins, homeostasis)
b. replicating DNA
(in preparation for dividing)
c. make enzymes for division, and organelles for the new cell
I. The Cell CycleB. The Cell Cycle
2. Mitosis (Nuclear Division)
a. Prophase
1. chromatin coils into chromosomes
I. The Cell CycleB. The Cell Cycle
2. Mitosis (Cell Division)
b. Metaphase
1. chromosomes line up at equator
2. centrioles move to poles
3. spindle fibers appear
I. The Cell CycleB. The Cell Cycle
2. Mitosis (Cell Division)
c. Anaphase
1. centrioles pull sister chromatids apart
I. The Cell CycleB. The Cell Cycle
2. Mitosis (Cell Division)
d. Telophase
1. spindle fibers break down
2. chromosomes uncoil
3. nucleus reappears
I. The Cell CycleB. The Cell Cycle
2. Mitosis (Cell Division)
e. Cytokinesis
1. final division of cytoplasm
2. cells separate
Asexual Reproduction and Cancer
II. Asexual Reproduction
A. Types
1. Budding (bud)
a. bud that is released from cell and grows into clone
b. common in yeast (fungi)
II. Asexual ReproductionA. Types
1. Budding
2. binary fission
a. “split in two”
b. bacterial mitosis (some protists)
II. Asexual ReproductionA. Types
1. Budding
2. binary fission
3. fragmentation
a. growth of new organism from fragments of parent organism
III. Cancer and the Cell Cycle
A. What is Cancer?
1. uncontrolled cell division
2. results in a tumor
a. benign
1. harmless growth
2. no death to surrounding tissue
III. Cancer and the Cell Cycle
A. What is Cancer?
2. results in a tumor
b. malignant
1. tumor causes damage/death to surrounding tissue
2. spreads easily (metastasis)
III. Cancer and the Cell Cycle
A. What is Cancer?
3. caused by mutation in cell cycle genes
a. “On” genes work
b. “Off” genes don’t work
