Cell GrowthCell Growth

Section 10-1Section 10-1

Limits To Cell GrowthLimits 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

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

DNA OverloadDNA 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

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

DNA Overload Cont.DNA Overload Cont.

If a cell were to grow without limit an “information crisis” would occur

If a cell were to grow without limit an “information crisis” would occur

Exchanging MaterialsExchanging 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

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

Exchanging Materials Cont.

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

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

Surface Area To Volume Ratio

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.

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.

Cell DivisionCell 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 divisioncell division The two cells that result are called “daughter cells” because they are identical to one another

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 divisioncell division The two cells that result are called “daughter cells” because they are identical to one another

Cell Division Cont.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

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

Cell Division Cont.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

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