1. Microbiology: The study of small life All living things divided into 3 domains –Eubacteria: prokaryotic cell structure –Archaebacteria: prokaryotes, but different –Eukaryotes: 4 kingdoms Plants, animals, fungi, and protists. What are microbiologists interested in? –Eubacteria and archaebacteria for sure. –Eukaryotes like fungi and protists –Animals (parasitic worms) but not really plants. –What’s missing? –VIRUSES! 1

2. What is “life”? Cell theory: all living things are made of cells –Schleiden and Schwann, 1839 –Eukaryotes and prokaryotes: different kinds of cells –Excludes viruses, but we can argue later! Living things organized into complex structures –We will compare prokaryotes and eukaryotes Living things obtain energy / carry out chemistry –Bacteria are very diverse in how they do this! –Most bacteria of medical interest grow by aerobic metabolism or by fermentation (without oxygen) –Without energy source, bacteria don’t grow! 2

3. Life?- 2 Living things are able to reproduce –All life comes from pre-existing life –Knowing when and how bacteria reproduce is important for controlling their growth. –All living things have DNA as a blueprint Living things respond to their environment –Bacteria are small and simple in structure –They are successful because they can change themselves rapidly in response to their environment. –Bacteria tightly control which genes they use and when. 3

4. 4 The study of chemistry (and biochemistry) is necessary to understand Microbiology Habitat Diet All living things are made of chemicals!

5. 5 Atom: smallest unit of an element Elements differ by number of protons http://www.perceptions.couk.com/imgs/atom.gif

6. 6 Molecule: atoms joined together with covalent bonds Electrons are shared between atoms. Covalent bonds are strong. When atoms in the molecule are of different elements, the substance is called a “compound”. http://www.truenorthgb.com/images/molecule.jpg

7. 7 Covalent bonds & polar molecules Water Covalent Bonds: sharing of electrons between the oxygen and hydrogen atoms. Strong. Oxygen is an electron hog; the electrons spend more time there leaving the hydrogen’s proton nearly naked (and somewhat positive): Water is a polar molecule mdp2.phys.ucl.ac.uk/ Talks/Ice/Ice.html

8. 8 Hydrogen bonds: Electrical attraction between electronegative oxygen atom and nearly naked proton. Bonds made between polar molecules. Weak bonds.

9. 9 H-bonds hold large molecules together Example: A-T base pair in DNA http://www.mun.ca/biology/scarr/Fg10_16a.gif

10. 10 Hydrophilic and hydrophobic Surfaces made of molecules without polar groups (e.g. CH 3 CH 2 CH 2 CH 2.) repel water.

11. 11 pH= -log [H+] Logarithmic pH 7 is neutral Ranges from 0-14 Molecules that release H+ are acids; those that release OH- are bases. http://www.btinternet.com/~chemistry.diagrams/ph_scale.gif H 2 O  H + + OH - [H+] = 10 -7

12. 12 Functional Groups

13. The Chemicals of life are large and small Cells contain molecules of all sizes but are MADE of large molecules called polymers –Polymer: a large molecule made of many similar or identical subunits. –“poly” means “many” (polyethylene, polysaccharide) –The small molecules that make up a polymer can be called “monomers” “mono” means “one” In our, not all polymers are biological –Plastics are all polymers too 13

14. 14 Small molecules (monomers) and macromolecules (polymers) Ethylene and polyethylene

15. 15 Four Classes of Biological Molecules Carbohydrates –Sugars and their polymers Nucleic acids and nucleotides –DNA, RNA, ATP Lipids –Various hydrophobic molecules Proteins and amino acids

16. 16 Carbohydrates: CH 2 O Monosaccharides: glucose, fructose, many others Disaccharides: sucrose, lactose Oligosaccharides: found on glycoproteins, in cytoplasm (oligo- means “few”) Polysaccharides: starch, glycogen, cellulose, agar, chitin, xanthan gum

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20. 20 A nucleotide: a monomer of DNA http://www.emc.maricopa.edu/faculty/farabee/BIOBK/nucleotide.gif

21. 21 Nucleic acids are the polymers made from nucleotides. DNAtRNA http://www.biochem.uwo.ca/meds/medna/IMG/tRNA.GIF

22. 22 Structure of DNA http://academic.brooklyn.cuny.edu/biology/bio4fv/page/molecular%20biology/16-05-doublehelix.jpg

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24. 24 Phospholipids are essential building blocks for membranes; sterol-type molecules are rarely found in bacteria.

25. 25 A lipid polymer: a biodegradable plastic made by bacteria. Ester bond Polyesters

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28. 28 Peptide bond covalent bond that connects two amino acids.

29. 29 Levels of protein structure Primary: amino acids and the order they are in; determined from the DNA. Secondary: alpha helix and beta pleated sheet; twisting of chain in space. Tertiary: 3D shape of protein. Quaternary: more than 1 polypeptide combining to form a functional unit. http://www.contexo.info/DNA_Basics/images/proteinstructuresweb.gif

30. Role of these molecules in cell structure Polysaccharides –Present in protective layers around the cell –Part of cell wall Nucleic acids –Blueprint of cell, location of genes –Ribosomes contain RNA Lipids –Major component of cell membranes, barrier Proteins –Enzymes, carry out chemical reactions –Structural components 30

31. Don’t forget the water ALL living things require water –Water is major component of cytoplasm –All small molecules are dissolved in water –All large molecules have water attached to them –Cells modify their chemistry to retain water –You die of dehydration before you starve Every polymer, every structure in the cell is surrounded by water. 31 http://media.nasaexplores.com/lessons/04-070/images/faucet.jpg

32. Review Microbes include –Bacteria, which are prokaryotic cells –Fungi and protozoa, which are eukaryotic cells –Viruses, which are not cellular so maybe not alive All of these are comprised of 4 types of molecules –There’s small and large example of all 4 types So Why do we study microbes? 32 www.pasteur.fr/.../im/micros/pasteur%20copie.jpg

33. Why Study Microbes? Major impact on health –Responsible for disease in humans, animals, plants Major impact on environment –Major decomposers –Nutrient cycling, elemental cycling Microbes are talented Live under extreme conditions Protect against disease Eat oil, toxic waste (bioremediation) Make plastic Spoil food, make food Use light, produce light 33