HUBS1404 Lecture Notes - Lecture 6: Plasmid, Gram Staining, Petri Dish
30 Jul 2018
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Document Summary
Bacteria and viruses are of major importance to humans. However, they are very different in structure and function. Bacteria were the first colonizers of the earth around 4 billion years ago. Cytoplasm contains ribosomes, dna in nuclear region an usually granules/vesicles. May also include plasmids - small circular dna. Many have external structures - flagella, pili etc. Mostly fall into, either, the rod shaped or circular shaped. All bacteria possess a cell (plasma) membrane - phospholipid bilayer. Protects the bacteria from all types of environment. Disaccharides cross-linked by peptides forming a stable network. A rigid scaffold that bacteria uses to form a wall around it. Most bacteria can be classified into two major groups based on cell wall composition. Gram-positive cell wall contains a thick peptidoglycan layer. Gram-negative cell wall contains a thin peptidoglycan layer covered by an outer membrane. If the cell wall is damaged then the bacteria would die.
