Bacteria Structures Sept. 11

IV. Non-Cellular Organisms
-Questionably alive because it needs a host cell to survive and reproduce
a. Viruses: Must use host cell’s genetic machinery to replicate themselves & smaller than bacteria
-Living things have DNA as their genetic material but some viruses don’t
-Bacteria: 1-5 µm (µm=10^-6)
-Viruses: 20-500 nm (nm=10^-9)
-Hundreds of times smaller than bacteria
i. DNA Viruses: Have DNA as genetic material
ii. RNA Viruses: Have RNA as genetic material
1. Retroviruses: Often lead to cancer because of effects on genetic machinery of host cell
b. Prions: No genetic material, just proteins but can still replicate

I. External Bacterial Layers
a) Polysaccharide Capsule: Carbohydrate coat outside of outer bacterial layer (thicker layer)
a. Beneficial- pulls water out of the atmosphere (drying out)
b. Helps prevent phagocytosis
b) Crystalline Surface Layers
a. Made of protein
b. Same advantages as cpsule
c) Biofilms:
a. Lipids, carbohydrates, proteins
b. Built by communities
c. Prevents from drying out
d. Same advantages of crystalline surface layers and capsules, plus: Protects
against antibiotics and disinfectants (neither can get through the gel)
Bacterial DNA is tight, wound up bunch when not being used
DNA gyrase unwinds bunches—>ciprofloxacin destroys

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