THE BACTERIA CELL

Bacteria are very small unicellular organisms. They can only be seen with the help of a strong power microscope. Bacteria are prokaryotes.ie Their nucleus is not bounded by a nuclear membrane.

GENERAL CHARACTERISTICS OF BACTERIA

1. A bacterium has a nucleus which is not bonded by a nuclear membrane but with a cellular DNA.
2. Bacteria are larger than viruses and can be seen with both light and electron microscope.
3. Bacteria have a mass of cytoplasm covered by a cell wall.
4. Cell wall of bacteria is made up of protein and fatty substances and not cellulose or chitin.
5. Bacteria store food as glycogen.
6. Some bacteria have chlorophyll found in a cytoplasm and not chloroplast.
7. Some have flagellum used for movement.

STRUCTURE OF A BACTERIUM CELL

A bacterium cell simply consists of a mass of cytoplasm covered by a firm cell wall. Nuclear material is preset but not arrange in a definite nucleus. Some bacteria have flagellum. The slime capsule and cell wall protect the cytoplasm.

MORPHOLOGICAL OR STUCTURAL TYPES OF BACTERIA

1. Bacilli or Rod Shaped Bacteria

Bacilli that occur in pairs are called Diplobacilli:         

Those that occur in chains are called Streptobacilli:

Eg: Salmonella typhi which causes typhoid fever.

2. Cocci(Coccus)

Cocci are spherical bacteria; Cocci that occur in pairs are called Diplococcic:

Those that occur in chains are called Streptococci:                                                           while those that occur in clusters are called staphylococci:

Eg: Staphylococcus avreus which causes boils.

3. Comma Shaped Bacteria

Eg: Vibro cholerae which causes cholera.

MODE OF LIFE OF BACTERIA

• Movement:

Bacteria are motile. That is, they can move, some move using flagella.

• Reproduction:

Reproduces asexually by binary fission. The nucleus of one parent cell divides transversely into two to produce two identical daughter cells.

• Favorable Temperature:

Most bacteria survive at a temperature favorable to other living organism. They are inactivated at low temperatures and killed at very high temperatures.

• Respiration

Bacteria that use oxygen for respiration are called aerobic respiration or aerobes those that do not use oxygen are called anaerobic bacteria. Some can grow either in the presence or absence of oxygen (facultative bacteria).