Cell Growth Division Cell Growth Living things grow

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Cell Growth & Division

Cell Growth & Division

Cell Growth • Living things grow because the number of cells increase, NOT because

Cell Growth • Living things grow because the number of cells increase, NOT because the size of the cells increase. (Increase in #, not physical size) • The size of a cell in an adult is no different than the size of a cell in a baby.

Requirements for a Healthy Cell 1. A cell must be able to get the

Requirements for a Healthy Cell 1. A cell must be able to get the nutrients it requires. 2. A cell must be able to get rid of waste products it produces. 3. If a cell can not do both, it will either die, stop growing, or divide. 4. With the exception of a few types of cells, most cells will divide.

Limits on Cell Growth • Cells divide because of their volume to surface area

Limits on Cell Growth • Cells divide because of their volume to surface area ratio. • As the cell increase in size, it requires more nutrients and produces more waste. • The only location where nutrients and waste are exchanged are in the cell membrane.

Rate of Cell Growth • Controlled Cell Growth – Most cell stop growing when

Rate of Cell Growth • Controlled Cell Growth – Most cell stop growing when they come in contact with (touch) other cells. – It is not completely understood why they stop growing, but growth can be turned on and off depending on the condition. (Cyclin) • Uncontrolled Cell Growth – In the right conditions, certain bacteria can divide every 30 minutes. – Cancer is an example of a type of cell that does not stop growing when it comes in contact with another cell.

Cell Division • Somatic Cells: Those cells that make up the human body. •

Cell Division • Somatic Cells: Those cells that make up the human body. • Sex Cells: Those cells that are involved in reproduction, the sperm in males & egg in females. • Chromatin: Uncoiled DNA wrapped around protein balls called histones. • Chromosomes: Coiled up Chromatin – The parts of a chromosome: • Chromatids- Two condensed strands of DNA that are identical to each other. • Centromere- Location where two chromatids are attached

Example of Cell Types • Somatic Cells- normal body cells • Sex Cells- Those

Example of Cell Types • Somatic Cells- normal body cells • Sex Cells- Those cells used during reproduction; sperm and egg cells. • Stem Cells- Cells that can become other cell types. Can be used in multiple medical treatments ( for example; repair damaged nerve cells) • Cancer Cells- Cells that can’t control their growth

Limits on Cell Growth • If the cell volume increase much faster than surface

Limits on Cell Growth • If the cell volume increase much faster than surface area and therefore does not allow for sufficient exchange of nutrients and waste. • In order to survive, the cell must divide.