Today

• Pick up a handout

• Schedule– Wrap up immunity– Bacteria notes– Start microscope lab

Bacteria - Kingdom Monera

Objectives

• Eubacteria vs. Archaebacteria

• Typical bacteria structure

• Bacterial classification

• How bacteria obtain genetic variation

• Uses and harmful effects of bacteria

History of Life

III. Kingdom Archaea “bacteria”1. Have no peptidoglycan in their cell wall

2. more closely related to eukaryotes (ribosomes)

3. Different lipid composition in plasma membranes

4. Live in harsh climatesa) Methanogens – oxygen-free environment like

intestines, swamps, sewers (produce methane gas)

b) Thermophiles – hot environments – undersea volcanic vents, hot springs

c) Halophiles – salty environments – Great Salt Lake, Dead Sea

d) Acidophiles – live in extreme pH

Bacterial RespirationObligate aerobes – organisms that require a constant supply of oxygen in order to live. EX: Mycobacterium tuberculosis, the bacterium that causes tuberculosis.

Obligate anaerobes – do not require oxygen; some may be killed by O2! EX: Clostridium botulinum, found in soil and can grown in canned food causing fatal food poisoning.

Facultative anaerobes – can survive with or without O2. EX: E. coli, can live in the large intestines contaminated water.

Respiration

Obligate Aerobe

Obligate Anaerobe

FacultativeAnaerobe

Microaerophile

Aerotolerant

Eubacteria

• Prokaryotic

• (no nucleus) – larger than viruses

• Peptidoglycan in

cell wall

• Can be decomposers

Other structures• Capsule – outer layer made of

polysaccharide or protein, used for adhesion

• Fimbriae – specialized pili for attachment

• Plasmid – extra circular pieces of DNA

Classified by

• Nutrition

• Movement

• Shape

• How they colonize (clusters, pairs, etc)

• Cell wall composition

• Production of endospores

Nutrition1. Photoautotrophic – photosynthetic, use sunlight

for energy, CO2 for carbon (cyanobacteria, algae, plants)

2. Chemoautotrophic – use inorganic compounds as electron donor for energy, uses CO2 for carbon (some prokaryotes)

3. Photoheterotrophic – sunlight generates ATP, must get carbon from organic molecules (some prokaryotes)

4. Chemoheterotroph – energy and carbon must come from organic compounds (most organisms including prokaryotes)

Coccus - round

Bacillus - rods

Sprillium - spirals

(Chains)

(Clusters)

Gram Stain

Classified by Gram Stain

1. Gram Positive• 1 cell wall of glycoproteins & lipid

• Stains PURPLE because stain penetrates the single wall

2. Gram Negative• Has 2nd outer layer – prevents stain

from penetrating (Purple stain washes off)

• New RED stain applied and sticks

• Resistant to antibiotics

Endospore – protects the cell against harsh environmental conditions, such as heat and drought. May allow the bacterium to survive for thousands of years.

Today

• Have out:– Bacteria notes– Lab Diagram Sheet

Objectives

• Eubacteria vs. Archaebacteria

• Typical bacteria structure

• Bacterial classification

• How bacteria obtain genetic variation

• Uses and harmful effects of bacteria

Genetic Diversity in Prokaryotes1. Rapid reproduction

a. Binary Fission

2. Mutationa. 1 in 10 million chance of a mutation in each gene

b. This leads to 9 million mutations in the E. coli present in your intestine

3. Genetic recombinationa. Transformation – taking up of foreign DNA

b. Transduction – From bacteriophages

c. Conjugation

Growth & ReproductionBinary Fission – bacterium doubles in size, it replicates its DNA and divides in half.

Transformation

Transduction

Conjugation

• F (fertility) plasmid – has genes for creating sex pili

• R (resistance) plasmid – contains antibiotic resistance genes

Major groups of bacteria

• Cyanobacteria - photosynthetic

• Chemosynthetic bacteria – nitrifying

• Nitrogen-fixing bacteria – live in nodules on plant roots

• Spirochetes – coiled, move in corkscrew motion, internal flagella

Cyanobacteria – blue-green algae

Non-oxygenic photosynthesis

• Bacteriochlorophylls• H2S provide electrons• Only 1 photosystem

(PSI)• Cyclic

photophosphorylation

Importance of Bacteria•Nutrient cycles

•Decomposition

•Oxygen production

•Food – baking & beverages

•Clean up oil spills, rivers & streams

•Make drugs

•Aid in digestion

Bacteria & DiseasePathogen – bacteria that cause disease or a disease causing agent.

Exotoxins – toxic proteins secreted by bacterial cells, includes some of the most potent poisons known.

Clostridium botulinum – one gram of the exotoxin that causes botulism could kill 1,000,000 people!

Staphylococcus aureus – harmless, found on skin; if it enters the body through a wound it can cause layers of skin to slough off, vomiting, severe diarrhea & deadly toxic shock syndrome.

Bacteria & DiseaseEndotoxins – are NOT secretions; but components of cell walls in bacteria: glycolipids, which are large molecular complexes of polysaccharides & lipids.

All endotoxins induce the same general symptoms: fever, aches and sometimes a dangerous drop in blood pressure (shock).

Salmonella – produces endotoxins that cause food poisoning & typhoid fever.

AntibioticsAntibiotics are drugs that combat bacteria by interfering with various cellular functions

Some bacteria are antibiotic-resistant and destroy antibiotics, or prevent entry of the antibiotic into the cytoplasm.

Microscope Lab• Columns

– Name– Diagram– Visible structures– Prokaryotic or Eukaryotic– Autotrophic or Heterotrophic

• Look at– Bacteria

• Bacilli, cocci, spirilla

• 2 other bacterial slides of your choice

– Protist• Pick 5 of them