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Carbon is the structural backbone of the organic compounds that make up a living
cell. Based on their source of carbon bacteria can be classified as autotrophs or
1. Autotrophis: require only carbon dioxide as a carbon source.
2. Heterotrophis: require organic forms of carbon.
Phosphorus: Phosphorus is needed to synthesize phospholipids, DNA, RNA, and ATP.
Phosphate ions are the primary source of phosphorus.
Potassium, magnesium, and calcium: These are required for certain enzymes to
function as well as additional functions.
Iron:Iron is a part of certain enzymes.
Trace elements: Trace elements are elements required in very minute amounts, and
like potassium, magnesium, calcium, and iron, they usually function as cofactors in
enzyme reactions. They include sodium, zinc, copper, molybdenum, manganese, and
cobalt ions.
Growth factors
Growth factors are organic compounds such as amino acids, purines, pyrimidines,
and vitamins that a cell must have for growth but cannot synthesize itself.
Size of bacteria: Most bacteria are so small that their size is measured in units called
micron. The unit of measurement is the micro-meter, written m
Bacterial Nomenclature (Name of bacteria): Bacteria classify under the national taxonomy
like an other microorganisms by :

KingdomPhylum ClassOrderFamilies GenusSpecies
a. Types OR

b. Strain OR

c. Varieties.

And the name of bacteria writes according to:

Genous name species name …..

e.g. Salmonella typhi

Salmonella typhi

Salmonella paratyphi A

Salmonella paratyphi A

Salmonella paratyphi B

Salmonella paratyphi B

Structure of bacteria: - representation of a bacterial cell showing some of the essential
1. The cytoplasmic membrane consists of a layer of lipoprotein and is 5-10 nm thick. It
encloses the Cytoplasm
2. The cell wall is complicated lattice structure of lipoprotein, lipopolysaccharide and
peptidoglycan, which gives the bacterial cell its shape and also protects the cytoplasmic