Bacteria

Hand Washing 1800’s: 25% of women died after childbirth

Why? Streptococcus pyogenes bacteria

But most women were perfectly healthy before entering the hospital.

Doctors were passing the deadly microbes on to healthy women because they NEVER washed their hands!!

*Prokaryotes vs. EukaryotesBefore we examine bacteria we need to know the difference between Prokaryotes and Eukaryotes

There are two types of cells that exist: Prokaryotes and Eukaryotes

Property Eukaryotes Prokaryotes

True nucleus Yes No

Genetic Material Many chromosomes usually

Single chromosome

Cell Division Mitosis + Meiosis Binary or Other

Number of cells in organism

1 or more (to trillions)

1 (unicellular)

Size Larger cells Smaller cell

Metabolism Aerobic (require O2) Anaerobic (no O2 needed)

BacteriaAll bacteria are:

Unicellular

Have prokaryotic cells

Live in a moist environment.

Reproduce mainly through binary fission.

Have one circular chromosome called a plasmid.

There are 2 types of bacteria:ArchaebacteriaEubacteria

Defining Features of Bacteria

1) Shape/Arrangement

2) Cell Wall

3) Nutrition & Gas Exchange

4) Movement

5) Genetic Components/Reproduction

1. Shapes & Arrangements

Eubacteria have many different shapes and arrangements.

Shape Latin Arrangement Latin

Round Coccus (Cocci) Paired Diplo-

Rod Bacillus (Bacilli) Chain Strepto-

Spiral Spirilla Clump Staphylo-

Corkscrew Spirochete

1. Shapes & Arrangements

E. ColiEscherichia coli

(E. coli)

Where is E. coli?- In the human intestines- They help in digestion and vitamin B

and B production

What shape?-Bacillus

How big is E. coli?

2. Cell Wall

Some bacteria are classified by the cell wall’s response to gram stain

Gram stains show differences in amino acid and sugar molecules

Identifying Bacteria

3. Nutrition & Gas ExchangeBacteria can exist as:

1) Aerobic (need oxygen) or anaerobic (do not need oxygen to survive

2) Autotrophic (make own food) or heterotrophic (need to eat food)

3. Nutrition : Types of Autotrophic Bacteria

Photosynthetic Organisms make their own food using energy from light

Chemosynthetic Obtain energy from inorganic compounds such as hydrogen gas to hydrogen sulfide

Do not require light

4. Movement

Cilia: Hair-like projections that work together in rhythm

Flagella (sing: flagellum): Tail-like projection that helps push bacterium (similar to a tad pole)

5. Reproduction in Bacteria

1) AsexualBinary Fission

2) SexualConjugation

Asexual: Binary Fission Similar to mitosis but simpler

DNA replicates and half moves to one end and other half goes to the other

Cross wall divides two identical bacteria

Bacteria can separate or remain together

Makes Diplo-, Staphylo-, Strepto- bacteria

Sexual: Conjugation

Donor and recipient bacteria make cell to cell contact

Via a sex pilus

Plasmids (DNA) are exchanged from donor to recipient

Plasmids are small loops of DNA that separated from the bacterium chromosome

EndosporesSome bacteria form endospores

This allows them to survive under high temperatures, freezing, radiation, drying out etc.

When conditions are suitable, the endospore germinates back into an active bacterium (ranges from weeks to 1000’s of years)

Bacteria and Humans

Strep throat caused by Streptococcus pyogenes

Tooth decay (cavaties) cause by Streptococcus mutans

Bacteria and Humans

Leprosy caused by Mycobacterium leprae

Tetanus (muscle spasm) caused by Clostridium tatani

Archaea• Oldest organisms on

earth = very primitive.• Live in extreme

conditions.• 3 Types:

1. Thermophiles (survive in high temp)

2. Methanogens (survive in high levels of gas)

3. Halophiles (survive in high salt concentrations)

*Comparing Bacteria and Archaea

Homework

Read pages 59-66#1-6, 8, 10 (p.66)