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Cell Growth

Cell Growth. Section 10-1. Limits To Cell Growth. There are two main reasons why cells divide DNA OVERLOAD : The larger a cell becomes the more demands the cell places on its DNA

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Cell Growth

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  1. Cell Growth Section 10-1

  2. Limits To Cell Growth • There are two main reasons why cells divide • DNA OVERLOAD: The larger a cell becomes the more demands the cell places on its DNA • EXCHANGE OF MATERIALS: The larger a cell becomes the more trouble it has moving enough nutrients and wastes across the cell membrane

  3. DNA Overload • All of the information that controls a cell’s functions is stored in the DNA • When a cell is small the information stored in the DNA is able to meet the cell’s needs • As a cell increases in size the DNA can not keep up with all of the demands which are placed on it

  4. DNA Overload Cont. • If a cell were to grow without limit an “information crisis” would occur

  5. Exchanging Materials • Food, oxygen, and water enter the cell through the cell membrane • Waste products leave in the same way • The rate at which this exchange of materials takes place depends on the surface area of the cell • This is the total area of the cell membrane

  6. Exchanging Materials Cont. • However the rate at which food and oxygen are used up and waste products are produced depends on the volume of the cell • Understanding the relationship between a cell’s volume and its surface area is the key to understanding why cells must divide

  7. Surface Area To Volume Ratio • The volume of a cell increase much more rapidly than the surface area • As a result the ratio of surface area to volume ratio decreases • Surface area = l x w x 6 sides • Volume = l x w x h • A cell will have increasing difficulty moving oxygen and nutrients into the cell and moving waste products out as it increases in size.

  8. Cell Division • A cell will divide into two cells before it reaches the point of DNA overload or the exchange of material becomes a problem • The process is called cell division • The two cells that result are called “daughter cells” because they are identical to one another

  9. Cell Division Cont. • Before cell division occurs the cell replicates or copies all of its DNA • The replication of DNA solves the problem of information storage • Each daughter cell gets one complete set of genetic information

  10. Cell Division Cont. • Cell division also solves the problem of increasing size by reducing the cells volume • Each daughter cell has an increased ratio of surface area to volume • This allows for efficient exchange of materials with the environment

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