Chapter 10.1 Cell Growth

Cells will not grow to enormous size and there are 2 main reasons - the larger a cell is the more demands the cell puts on its DNA and the larger it is the harder it is to move enough nutrients and wastes across the cell membrane. Limits to Cell Growth

DNA controls the cell’s functions and is found in the nucleus of a cell. As a cell grows larger, it does not make more DNA, instead the DNA it has would not be able to keep up with the demands of a large cell. DNA “Overload”

Remember food, water, and oxygen enter the cell through the cell membrane, cell waste leaves through the membrane. The amount of food and oxygen being used up and waste being made is dependent on the volume of the cell. The cell membrane is the surface area of the cell. This ratio is important in limiting the size of a cell. Exchanging Materials

Ratio of Surface Area to Volume We will use a cube as an example – if a cubes sides are equal to 1 cm then the surface area would be 6 cm2 (1 cm x 1 cm x 6 (# of sides)). The volume would be 1 cm3 (1cm x 1 cm x 1cm). The ratio of surface area to volume would be 6:1. If we increase the sides to 2 cm the new surface area would be 24 cm2 and the volume 8 cm3. The new ratio would be 3:1 This shows us that the volume increases faster than the surface area. If the cell gets too large it cannot get enough oxygen and nutrients in and wastes out. Ratio of Surface Area to Volume

Cell division is the process a cell undergoes to divide one cell into 2. Before a cell can divide it has to make copies of its DNA. Division of the Cell