Bacteria TEST: 11/6

What are bacteria? Prokaryotes Microscopic (nanometers!) No nucleus Circular DNA (not chromosomes) Few organelles Microscopic (nanometers!) Plasmids: -circular DNA fragment -additional genes -provide resistance and/or adaptations

Classification Kingdom Eubacteria Kingdom Archaebacteria Staph Normal bacteria Found everywhere Cell wall of peptidocylcan EX: E. coli, staph Kingdom Archaebacteria Extremophiles; ancient Live in extreme conditions Cell wall lacks peptidoglycan EX: Methanogens Staph

Multicellular organisms Bacterial Evolution Prokaryotes were first in fossil record Change in Earths atmosphere Presence of O2 allowed bacteria to diversify 1st living organism Archeobacteria (chemosynthetic) 3.8 BYA 2 BYA Eukaryotic cell Complex cells Life forms diversify 1 BYA Multicellular organisms 3 BYA Photosynthesis O2 level increased 4.5 BYA Earth formed

Still Successful on Earth after 3.5 Billion Years! Variety & Diversity in Both Domains Still Successful on Earth after 3.5 Billion Years!

Bacteria Identification 3 methods to identify a bacteria: Shape Cell Wall Movement Petri dish with bacterial growth

1) Shape Bacilli: rod-like Spirilla: spiral-like Cocci: sphere-like Diplo—pair Strepto—chain Staphlo—clump

Name…based on shape Streptococcus Staphlococcus Diplobacillus

2) Movement How do they move? Glide in ooze Flagella or cilia Snake or spiral

Energy needs in bacteria Heterotrophs: “eat” for energy Autotrophs: Photosynthesis Or Chemosynthesis What is a Photo-heterotroph? eat for energy and photosynthesis Autotrophic Cyanobacteria… >3.5 BYA Oldest know fossils! O2 in the air

Cellular Energy— Photosynthesis Autotrophic bacteria use the sun’s energy to make sugars Glucose LIGHT 6H2O + 6CO2 ------> C6H12O6+ 6O2 CHLOROPHYLL

Cellular Energy— Respiration Heterotrophic bacteria to release energy found in organic compounds C6H12O6+ 6O2 ------> 6H2O + 6CO2 Or C6H12O6 ------> 6H2O + 6CO2

Cellular Respiration Obligate Anaerobes: lives in absence of O2 EX: botulism in canned foods Obligate Aerobes: require O2 EX: tuberculosis, lives in the lungs

Cellular Respiration Facultative Anaerobes: live w/o O2, but won’t be killed in presence EX: E. coli, lives anaerobically in intestines and aerobically in sewage

Energy=Bacterial Reproduction Two methods of bacterial reproduction Binary fission Conjugation Growth is FAST…can replicate every 15-20 minutes!!

Binary Fission Reproduction Asexual Reproduction Steps: Growth Division Produces two identical daughter cells

Conjugation Reproduction Sexual Reproduction—exchange DNA Process: Hollow bridge forms between bacteria DNA is transferred from one cell to the other Uses more energy than binary fission so….why do it??? GENETIC VARIATION http://www.youtube.com/watch?v=O-EdX4MaMFE

3) Cell Walls Pink color Violet color 2 types of cell wall –distinguish with GRAM STAINING Gram-negative Pink color Complex cell wall Negative = bad bacteria, more resistant to antibiotics Gram-positive Violet color Simple cell wall Positive = good bacteria Salmonella Lactobacillus

Roles of Bacteria Symbiotic Relationships Probiotic Bacteria—keep the bad bacteria in our bodies in check E. coli—in intestines aids in digestion Lactobacillus—small intestine Lactobacillus

Roles of Bacteria Nature’s Recycling Machines Decomposers Nitrogen fixation—from N2 (nitrogen gas) to a form plants use Oil eating bacteria Break down raw sewage

Roles of Bacteria Many fermented foods are produced with the help of bacteria: Cheese Buttermilk Yogurt Sour cream Vinegar Pickles Sourdough bread

Pathogen—Disease causing agent Bacteria cause diseases in 2 ways Damaging cells Releasing toxins (poisons) Acne Propionibacterium acne

Homeostasis for survival 1) Balance with the environment 2) Cell membrane controls balance

About the cell membrane Selectively permeable Found surrounding all cells Double lipid layer creates perfect barrier RECALL : lipids are fats lipids repel water

Diffusion of molecules Concentration gradient (high to low) No energy required- kinetic Variables that affect rate: -concentrations -temperature -size of molecule

6 minute review! = equilibrium This is the goal! http://www.youtube.com/watch?v=moPJkCbKjBs&feature=related 6 minute review! = equilibrium This is the goal!

Osmosis = diffusion of water Occurs naturally to maintain homeostasis Usually causes a cell to change size Still occurs after homeostasis is reached

Cell Environments Isotonic Hypotonic Hypertonic

Isotonic Equilibrium Same percentage of molecules inside as outside Molecules still move… but remain balanced

cell wall prevents bursting HYPOTONIC Less solute outside of the cell Causes water to move in until solutes are balanced Cell enlarges and may burst (lyse) cell wall prevents bursting

Cell shape is important to proper functioning! HYPERTONIC More solute outside the cell Water moves out until solute concentration is balanced May cause cells to shrink/shrivel Cell shape is important to proper functioning!

FACILATED DIFFUSION Diffusion through channels- can be regulated unlike osmosis EX: Sodium - Potassium pump which makes muscle cells contract and relax properly

More Reviews if time! http://www.youtube.com/watch?v=AYNwynwaALo&feature=related 3 minutes http://www.youtube.com/watch?v=0eSyOvlbuNo 4 minutes

THE END!