Microbiology
Mar 26, 2015
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