Eubacteria Notes
Structure
1 - Rigid cell wall: provides shape & protects cell
2 - No membrane-bound organelles = prokaryotes (do have ribosomes)
3 - Plasmids: (circular loops of DNA) and one simple chromosome
4 - Capsule: thick, protective layer many harmful bacteria have this to
protect them from being digested by the host;s body
fluids ex: bacteria that cause pneumonia and syphillis
5 - Other: flagella (tail for movement), pili (hairs used for attachment),
and endospores
Nutrition
•Most are consumers - cannot make own food
Saprobes: feed on dead organisms (organic waste); important in soil
Parasites: absorb nutrients from another living organism (host)
Mutualism: lives on or in another organism and both benefit; ex: intestinal
bacteria and nitrogen-fixing bacteria
Respiration
•Obligate aerobe - requires oxygen for cellular respiration
ex: bacteria that cause throat & lung infections such as TB
•Obligate anaerobe - does not use oxygen & may be harmed by it
ex: tetanus (deep puncture wound); botulism
•Facultative bacteria - can get energy using oxygen (cellular respiration)
or by fermentation if oxygen is not available
*ex: E. coli
Reproduction
•Asexual - binary fission - bacterial cell duplicates DNA & divides into two
identical new cells
•Sexual - conjugation
-bacterial cell transfers its chromosomes to another cell through a
bridge-like structure called a pilus = genetic recombination
“variety”
Growth
1 - temperature range (most 79 - 100 degrees F)
2 – moisture (most are 90% water)
3 – darkness (sulight dries out & slows growth/ UV light damages DNA)
4 – food (variety - almost anything with carbon such as sugar, fat,
protein, or blood)
*some can metabolize inorganic material or even toxic substances
5 - correct oxygen requirements
Vocabulary Term
•Endospore - structure that forms when conditions are unfavorable
(too dry, no food, etc.) - “hibernation state” - no reproduction
occurs
*some have lasted ~ 50 years in this state
Controlling Bacterial Growth
-Refrigeration/Freezing
-Canning (no oxygen)
-Salt Curing
-Dehydration
-Radiation
-Chemical Preservatives
-Antiseptics
Importance to Life
-Nitrogen fixing: found on plant roots, these bacteria convert free nitrogen into
compounds that plants can use = natural fertilizer
-Food preparation: dairy products, pickles, olives, sauerkraut
-Alcohol fermentation: producing beer & wine
-Aid digestion
-Leather tanning: softens the hide
-Vaccines: use killed or weakened strains of bacteria & inject them into
organisms so that antibodies are produced
-Wrinkle treatment: Botox
-Genetic engineering: human hormones such as insulin, oil-eating bacteria,
insect resistance in plants, digestion of toxic substances
like DDT, etc.
Harmful Bacteria
•Cause disease
•Spoil food
Types of Food Poisoning
•Botulism
-produces exotoxin (toxin produced by the bacterial cell during
metabolism) which is harmful to humans
-Usually found in improperly canned foods
-Symptoms include dizziness, double vision, breathing difficulty &
potentially, death
•Staphylococcus
-Usually found in improperly stored meat, fish, & dairy
products
-Symptoms include vomiting & cramps
•Salmonella
- Usually caused by infected food handlers and found in food types such
as eggs, sausage, ground meats, or custards
-Symptoms include vomiting, cramps, diarrhea, aches & fever
Food Poisoning Prevention
1.Sanitary food handling techniques
2.Sterilization (canning)
3.Pasteruization
4.Refrigeration/Freezing
5.UV radiation