Unit 1.1 Topic 4

Cells and Living Processes

All living organisms are send to share seven characteristics - movement, respiration, sensitivity, nutrition, excretion, reproduction and growth. Some bacteria do not respire, but use other chemical reactions to obtain energy.

Many organisms consist of only a single living cell. Such cells exhibit all seven characteristics of living things. Living cells contain special structures that each carry out a particular function.

When you look undera light microscope, the most obvious feature you will see is the very large nucleus, you may also see chloroplast and large vacuoles in plant cells. These structures are organelles.

Using an electron microscope it is possible to identify a range of organelles in plant and animal cells. The detail inside the cells, is termed as the cells ultrastructure, (sometimes called fine structure).

Most organelles are found in both plant and animal cells. They have the same function in each type of cell. Each type of organelles has a specific role within the cell. This is called the Division of Labour. The different oraganelles work together in a cell, each contributing its part to the survival of the cell.

The Cytoskeleton.

The movement and stability of the cells is controlled by the cytoskeleton, flagella and cillia, vesicles and vacuoles and (in the case of plants), the plant cell wall.

Cells contain a network…