BACTERIATEST: FRI. 11/11

Bacterial Evolution

First living cells were prokaryotesSingle celled, NO NUCLEUS

Change in Earths atmosphere

1st living organismArcheobacteria

(chemosynthetic)

3.8 BYA

4.5 BYA

Earth formed

2 BYA

Eukaryotic cellComplex cells

Life forms diversify

Classification Kingdom Eubacteria

Normal bacteriaFound everywhereCell wall of

peptidocylcanEX: E. coli

Kingdom ArchaebacteriaExtremophilesLive in extreme conditionsCell wall lacks

peptidoglycanDNA similar to eukaryotesEX: Methanogens

Variety & Diversity in Both Domains

Still Successful on Earth

after 3.5 Billion Years!

How do bacteria get energy and grow??

Energy:Heterotrophs: eat for energyAutotrophs:

photosynthesis/chemisynthesisPhotoheterotrophs: eat for

energy and photosynthesisAutotrophic Cyanobacteria…• >3.5 BYA • Oldest know fossils!• O2 in the air

Bacteria Identification

3 methods to identify a bacteria:ShapeCell wallmovement

Petri dish with bacterial growth

Shape Bacilli: rod-like Spirilla: spiral-like Cocci: sphere-like

Diplo—pair Strepto—chain Staphlo—clump

Name…based on shape

Streptococcus Staphlococcus

Movement

Do they move?Yes/no

How do they move?

Snake or spiral

Glide in ooze

Flagella or cilia

Cell Walls2 different cell walls in bacteria –distinguish with GRAM STAINING

Gram-positiveViolet color Simple cell wall Positive = good bacteria

Gram-negativePink color Complex cell wall Negative = bad bacteria,

more resistant to antibiotics

LactobacillusSalmonella

Bacterial DNA Have circular DNA Plasmids: small circular

DNA fragments with additional genes—can provide resistance

Bacterial Diversity Antibiotic Resistance (passed via plasmids)

Transformation during time of stressBacteria will uptake any plasmid in environment

Resistance can also arise from spontaneous mutationsSome will survive exposure

to antibiotics some will not

o Bacteria can share DNA via conjugation (sexual reproduction)

Cellular Energy—Photosynthesis

Autotrophic bacteria can carry out photosynthesis using the sun’s energy to make sugars

LIGHT

6H2O + 6CO2 ------> C6H12O6+ 6O2

CHLOROPHYLL

Cellular Energy—Respiration

Heterotrophic bacteria carry out cellular respiration to get energy from organic compounds

C6H12O6+ 6O2 ------> 6H2O + 6CO2

Or

C6H12O6 ------> 6H2O + 6CO2

Cellular Respiration

Obligate Aerobes: require O2EX: tuberculosis, lives

in the lungs

Obligate Anaerobes: lives in absence of O2EX: botulism in canned

foods

Cellular Respiration

Facultative Anaerobes: live w/o O2, but won’t be killed in presenceEX: E. coli, lives anaerobically in

intestines and aerobically in sewage

Roles of Bacteria Symbiotic Relationships

Probiotic Bacteria—keep the bad bacteria in our bodies in check

E. coli—in intestines aids in digestionLactobacillus—small intestine

Lactobacillus

Roles of Bacteria

Nature’s Recycling MachinesDecomposersNitrogen fixation—

from N2 (nitrogen gas) to a form plants use

Oil eating bacteriaBreak down raw

sewage

Roles of Bacteria

Many fermented foods are produced with the help of bacteria:CheeseButtermilkYogurtSour creamVinegarPicklesSourdough bread

Pathogen—Disease causing agent

Bacteria cause diseases in 2 waysDamaging cellsReleasing toxins (poisons)

AcnePropionibacterium acne

Bacterial Diseases

Streptococcus (strep throat)Transmission: direct

contact with bodily fluidsSymptoms: fever, white

patches on tonsils

Bacterial Diseases Diphtheria

Transmission: sneezing, coughingSymptoms: sore throat, fever, swollen

glands

Bull Neck—swollen neck

Cutaneous Diphtheria

Bacterial Diseases

AnthraxTransmission:

inhalation of spores, through the skin

Symptoms: fever, severe difficulty breathing, death

Cutaneous Anthrax

Inhalation Anthrax

Bacterial Diseases

TuberculosisTransmission: inhalationSymptoms: fever,

difficulty breathing

Bacterial Diseases

BotulismTransmission: contaminated foodSymptoms: blurred vision,

difficulty swallowing, muscle weakness/paralysis

Bacterial Diseases Staphylococcus (staph infections)

Transmission: direct contactSymptoms: red scaly sores, can

spread to blood

Bacterial DiseasesDisease Transmission Symptoms

Streptococcus infections

Direct contact with saliva or nasal discharge

Fever, white patches on tonsils

Diphtheria Sneezing or coughing

Sore throat, fever, swollen glands

Anthrax Inhalation of spores

Fever, severe difficulty in breathing

Tuberculosis Inhalation Fever, difficulty in breathing

Botulism Contaminated food

Blurred vision, difficulty in swallowing, muscle weakness

Control of Bacteria

Antibiotics: medicines that stop bacteria growth by destroying cell wall

Sterilization: heat or disinfect

Cooking food all the way

Refrigeration: slows it down…does not kill it

Pasteurization

Pasteurization is a process of heating a food to a high temperature

This process slows/kills microbial growth in food

Created by Louis Pasteur