Microbiology

Bacteria1. How many cells?

2. Type of organism?

3. Nucleus?

4. Membrane bound organelles?

5. What kingdom are they in?

Unicellular

Prokaryotic

No

No

Monera

What does bacteria look like?

• Coccus (sphere) •Bacillus (rod)

•Spirillum (spiral)

• Autotrophic–Photosynthesis (use suns energy)–Chemosynthesis (use chemical energy)

How do bacteria get their energy?

• Heterotrophic–Saprophytic: obtain food from dead

organisms–Parasites: live off of living organism;

damage that organism–Mutualism: Bacteria and living organism

benefit (Ex: E. coli- intestinal bacteria)

Respiration• Aerobic: Live in presence of oxygen• Anaerobic: Live in absence of oxygen

Movement

• Flagella: Acts like a motor to propel bacteria forward• Slime layer: Secrete

slime and “slide” along the slime (similar to a slug)

Reproduction• Binary fission: asexual; divide in two• Conjugation: share DNA between two

bacterium• Endospores: Survive in extreme

conditions (temp, drought, flood, radiation)

• Bacteria are helpful–Nitrogen fixation,

food preparation, decay

• Bacteria are harmful–Disease, spoiled

food

Nitrogen Fixation

• Symbiotic (mutualism) relationship between bacteria and plants.–Bacteria get food

from plants, plants get nitrates from bacteria

Food Preparation• Bacteria are used

in the production of many foods such as buttermilk, cheese, yogurt, vinegar, and sauerkraut.

Decay: some bacteria are decomposers• Breakdown dead organisms sewage,

waste in landfills (help recycle materials back into soil)

Other Benefits• Antibiotic production• E. coli in human intestines (make vitamin K,

essential amino acids, digestion of some sugars)

• Genetic engineering• Cellulose digestion (symbiotic relationship with grazers)

Disease

• Most infections are caused by bacteria–Gangrene,

tuberculosis, leprosy, strep throat, pneumonia, syphilis, typhus

Spoiled Food

• Food poisoning is caused by bacteria–Botulism–Salmonella

Viruses

Structure• Protein coat surrounds a nucleic acid

core (DNA or RNA)• # of genes: few to over a hundred

Reproduction• Must have a host cell–Cannot reproduce

on its own• Two ways to

reproduce–Lytic cycle–Lysogenic Cycle

Lytic Cycle• Attachment of virus

to host cell• Inject DNA into host

cell• Replicate DNA• Assemble new virus

particles• Lyse (kills host cell)

Lysogenic Cycle

• Attachment of virus to host cell• Inject DNA into host cell• Viral DNA becomes part of host cell

(prophage)• Dormant, host cell reproduces• Activation and lyse

Diseases caused by Viruses

• HIV• Influenza

(flu)• Common

Cold