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Principles of Disease 16 > Introduction to Bacteria > Flashcards

Flashcards in Introduction to Bacteria Deck (10)

Describe the ways in which bacteria are identified by using particular features of their size, shape, growth requirements and staining characteristics.

o Gram Staining
• Gram positive - violet
• Gram negative - red

o Shape
• Cocci - Spherical
• Bacilli – Rod Shaped


Describe the main structures and functions of a typical bacterial cell

o Penicillin Binding Proteins - enzymes which synthesise peptidoglycans
o Peptidoglycans - give the cell strength and shape. Carbohydrate polymers cross linked with amino acids
o Lipopolysaccharide (LPS, endotoxin) - component of Gram Negative cell wall
o Flagellum - motility
o Fimbriae - adherence


Explain the classification of and nomenclature used for bacterial species.

The name is based on the genus and the species. Strains of a species has similar characteristics. Typing is used to identify strains.


Describe spores

Spores - a minute, typically one-celled, reproductive unit capable of giving rise to a new individual without sexual fusion, characteristic of lower plants, fungi, and protozoans. How they tolerate stress or unfavourable environments


Describe plasmids

Plasmids - a genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan. Plasmids are much used in the laboratory manipulation of genes. Involved in conjugation


How do bacteria replicate?

Binary fission to make identical progeny


How does genetic variation arise in bacteria?

o Spontaneous mutation
o Transfer of DNA


3 processes of DNA transfer

Conjugation - from filus of other bacterial cell
Transformation - from DNA in environment
Transduction - from a bacteriophage


Describe the culture of S. Aureus

Clustered gold round shaped bacteria, usually cultured on blood agar


Where do infections of nosocomialis bacterial species usually originate?

From hospital settings