Transcript Bacteria
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. Eukaryotes Before 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) Bacteria All 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: Archaebacteria Eubacteria 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. Coli Escherichia 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 Exchange Bacteria 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) Asexual Binary Fission 2) Sexual Conjugation 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 Endospores Some 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)