Bacteria Structure

• Essential Pieces? Movement?

Bacterial Structures

EndosporesEndospore: A defensive structure that enables the bacteria to live in harsh conditions

Contains DNA and ribosomes

Bacteria can survive in difficult temps, pH, and dry places

Resistant to antibiotics (Harmful to humans)

Classification of Bacteria• Shape

• Coccus- spherical

• Bacillus- rod

• Spirilla- spiral

• Arrangement

• Diplo- pairs

• Strepto- chains

• Staphylo- clusters

Measured in micrometers

= 10-6

Bacterial Shapes

Naming BacteriaName = Arrangement + Shape

Naming Bacteria

Bacterial EnvironmentsBest growth conditions (depends on bacteria)

1. Need a form of nutrition

2. Moisture for absorption

3. Suitable pH

4. Temperatures close to human body temps

1. Freezing water temp: 0ºC

2. Boiling water temp: 100ºC

3. Body temp: ~37ºC

Bacterial Reproduction- REVIEW!!

Asexual reproduction- No genetic variation, do not need two opposite gametes

Binary Fission

1. DNA uncoils and replicates

2. Bacteria grows as DNA is pulled to opposite ends

3. Wall/membrane closes forming two IDENTICAL cells

Bacterial Reproduction- REVIEW!!

Very fast

No genetic variation

Identical cells

Isolating Colonies

• Take observations — Any more growth?

• Isolate colonies, give procedure

Beneficial Uses of Bacteria

• Yogurt and cheese

• Digestion

• Used to make insulin

• Bioengineering

• Septic tanks and wastewater treatment

Identification of Infectious Diseases

1. Physical symptoms and x-rays

2. Gram stained and examined under a microscope

3. Cultured (grown) and treated with antibiotics in a petri dish

Treatment of Bacterial Infections

Discovery of antibiotics one of the biggest medical breakthroughs of all time

Broad spectrum vs. specific antibiotics

How do antibiotics work?

Interfere with cellular activities

Breakdown cell wall

Halt creation of proteins

Bacterial cell dies

Why are some bacteria difficult to treat?

What is antibiotic resistance?Definition: Evolution of bacteria strain that antibiotics are unable to kill

How does it happen?

Two main ways:

1. A mutation in the DNA sequence during binary fission leads to a more fit bacteria; survive and reproduce

2. Conjugation causes switch of plasmid (circular piece of DNA), which leads to a mutated bacteria

ConjugationExchanging bacteria’s DNA with another

Can be a section of the DNA (plasmid) or all of it

DNA transfers through pilus connection

Leads to genetic diversity and greater chance of mutation/evolution

Nonresistant vs. Resistant

Sources of EnergyAll living things need energy

Autotrophs- Photosynthetic, energy from sun

Cyanobacteria

Chemoautotrophs- Energy from chemicals

Many archaebacteria

Heterotrophs- Energy from other organisms

Saprotrophs- Carbon from decaying sources

Archaebacteria• Methanogens

• Produce methane gas

• Can be found in animal gut

• Halophiles

• Found in high salinity (salt)

• Ex. Dead Sea halophiles

• Thermophiles

• Found in higher temperatures

• Ex. Hydrothermal vents underwater

Examples of Bacterial Infections

Tetanus• Cause: Clostridium tetani

• Spores (can survive for years) in dust, soil, and animal waste

• Symptoms:

• Muscle cramps, weakness, lockjaw, respiratory distress, death

• Treatment: Vaccine, antibiotics, treat symptoms

Baby with Tetanus

Staph Infection (skin)• Cause: Staphylococcus aureus

• Commonly found on skin, but spread through open wounds

• Symptoms: Starts as small red bumps, turns into deeper abscesses, penetrates rest of body—> heart, lungs (fever, shortness of breath)

• Treatment: Antibiotics (sometimes intravenous)

Staph Infection on Skin

Tuberculosis• Cause: Mycobacterium tuberculosis

• Spread through air with infectious cough, sneeze, spit, etc.

• Symptoms: Affects lungs, chronic bloody cough, night sweats, fever, death if untreated

• Treatment: 6-12 months of antibiotics

Tuberculosis

E. coli Food Poisoning• Almost all food poisonings are bacterial

• Most types of E. coli are harmless and beneficial (over 700 types total)

• Cause: Escherichia coli

• Spread through eating undercooked or raw foods that are contaminated

• Symptoms: severe cramps, bloody diarrhea, vomiting, kidney failure, death

• Treatment: Rehydration

Lyme Disease• Cause: Borrelia burgdorferi

• Transmitted to humans through infected deer ticks (vector)

• Symptoms: fatigue, pain, blurred vision, headache, memory loss, stiff joints, bullseye rash

• Treatment: antibiotics if caught early

Toxic Shock Syndrome

• Cause: Staphylococcus aureus, Group A strep

• Associated with tampon use, open wounds, surgery

• Symptoms: sudden high fever, rash, vomiting, diarrhea, muscle aches, confusion, headaches, death

• Treatment: IV antibiotics

Gram Staining• Lab technique use to identify the composition of

a cell wall —> helps identify bacteria

Gram Positive (+) • Cell Wall =

Peptidoglycan • Absorbs stains; purple • Usually easier to treat

Gram Negative (-) • Cell Wall = Lipid layer

around thin cell wall • Does not absorb well; pink • Usually harder to treat

Gram Stain Result

Gram Stain Result

Gram Staining

Gram Staining Procedure1. Prepare smear - Sterilize loop, water on slide, sterilize

loop, place bacteria on slide, let dry.

2. Heat fixation- Run slide quickly over flame

3. Crystal Violet- Cover smear, let stand, DI water

4. Gram’s Iodine- Cover smear, let stand, DI water

5. Ethyl Alcohol- Decolorize, DI water

6. Safranin- Cover, let stand, rinse

7. Gently blot dry

Micrococcus Roseus= gram

positive staphylococcus

E. coli = gram negative

staphylobacillus