1 The study of biochemistry is necessary to understand Microbiology Habitat Diet

2 Why Chemistry? Conflict between microbe and host. Vibrio cholera toxin inserting into intestinal cells.

3 Terms and Definitions to review and Remember: Atom, protons, neutrons, electrons, isotopes, elements, molecules, ions, anions, cations, compounds, covalent bonds, ionic bonds, hydrogen bonds, pH, acids, and bases. Solution Suspension

4 Atom: smallest unit of an element Elements differ by number of protons

5 Molecule: atoms joined together with covalent bonds Electrons are shared between atoms. Forms strong bonds. When atoms in the molecule are of different elements, the substance is called a “compound”.

6 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

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

8 H-bonds hold large molecules together Example: A-T base pair in DNA

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

10 pH= -log [H+] Logarithmic pH 7 is neutral Ranges from 0-14 Molecules that release H+ are acids; those that release OH- are bases.

11 Functional Groups

12 Small molecules (monomers) and macromolecules (polymers) Ethylene and polyethylene

13 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

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

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18 A nucleotide: a monomer of DNA

19 Nucleic acids are the polymers made from nucleotides. DNAtRNA

20 Structure of DNA

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

23 A lipid polymer: a biodegradable plastic made by bacteria.

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