1. Prokaryotes: Bacteria

2. Bacteria Found on almost every square cm of Earth Bacteria = prokaryotes –Remember: no nucleus and no membrane bound organelles Typically very small (microscopic), usually a range of 1 to 5 micrometers

3. Classification Domain Bacteria; kingdom Eubacteria Most common bacteria Very diverse Peptidoglycan in cell wall

4. –Domain Archaea; kingdom Archaebacteria Extremophiles – live in extreme conditions No peptidoglycan in cell wall and different membrane lipids

6. Bacterial Genome (DNA) DNA is in the cytoplasm in nucleoid region Consists of one, double-stranded, circular chromosome May have smaller, circular pieces of DNA called plasmids –May only contain a few genes –May benefit bacteria, but are not necessary

8. Identifying Bacteria In order to identify, scientists look at several characteristics such as: –Shape –Cell wall composition –Methods of Movement –Nutrition and Metabolism

9. Shape Three main shapes: –Cocci – spherical-shaped Can be found singularly, in chains, or in masses –Bacilli – rod-shaped May be found singular or in chain- like groups –Spirilla – spiral or helical-shaped

10. Gram Stain In Eubacteria, there are two types of cell walls –Use gram stain method to identify –Consists of two dyes – violet and red Gram-positive bacteria – have thick, peptidoglycan walls –Stains violet Gram-negative bacteria – have thinner walls inside a lipid layer and much less pep. –Violet washes out and stain red or pink

11. Gram Stain - identification PositiveNegative

12. Movement Some do not move at all Some propelled by flagella –Whip or tail-like projections Some lash, snake or have corkscrew-like movements Some glide along a slime secretion

13. Nutrition Four main modes of nutrition: (involves getting energy and carbon) –Photoautotrophs – use light energy and CO2 to produce organic compounds (photosynthetic) –Chemoautotrophs – Use energy from chemicals and CO2 to produce organic compounds

14. –Photoheterotrophs – use light energy, but must consume organic compounds –Chemoheterotrophs – consume organic compounds for energy and carbon

15. Energy and Metabolism Bacteria make and release energy by cellular respiration, fermentation, or both –Obligate aerobes – require constant supply of O2; perform CR –Obligate anaerobes - poisoned by oxygen; must live in areas without it; perform fermentation –Facultative anaerobes – can survive with or without oxygen; can switch between CR and fermentation

16. Reproduction Most reproduce asexually by binary fission –Replicate DNA –Split into two identical bacteria –Can occur very rapidly –Growth held in check by available resources

17. Other characteristics Conjugation – allows some bacteria to exchange genetic info. –A hollow bridge (pillus) extends between two bacteria and allows for the transfer of genes from one cell to another Endospore formation – may occur when growth conditions become unfavorable –bacteria produce a thick internal wall that encloses DNA and cytoplasm; may remain dormant until growth conditions improve

18. Importance/Roles Some are producers Some are decomposers Recycling of nutrients –Carbon cycle –Nitrogen cycle – fixation and denitrification Symbiotic relationships –Mutualism in our intestines Commercial and industry use – foods, sewage treatment, oil spills Genetic engineering – protein production –insulin, human growth hormone, clotting factor) Source of disease/infection