1. What is Biology? Study of life & characteristics of life Expectations/learning outcomes: –Understand, explain, describe, & integrate the natural world of living things –Focusing on: How life works… rather than the “meaning of life”

2. Characteristics of Life? In other words… what are the essential properties/functions of “living” systems? DNA Cells Acquire & use energy Highly complex & organized Growth & development Metabolize chemicals Reproduce Evolve by natural selection

3. Levels of organization Biosphere Ecosystem Community Population Organism Organ system Organ Tissue Cell -------functional units of life Organelle Molecule Atom Subatomic particle

4. How can we study: all these characteristics, diversity, complexity… and, try to make sense of it? Scientific Method –What? –Why? –How?

5. Inductive approach: from specific observations to the general Deductive approach: use general principles in predicting specific outcomes Scientific Method

6. Complexity builds from the atomic level up (Ch. 2) Atoms –Chemical unit –Made up of subatomic particles Nucleus of an atom –Protons positive charge –Neutrons neutral charge Electrons –negative charge –Orbit around nucleus in energy shells (2,8,8…) –Determine chemical nature, reactivity, and interactions with other elements …incomplete shells create potential for interactions.

8. Lets make an atom of Carbon… Symbol for Carbon element Atomic number 6 protons Nucleus w/ 6 protons & 6 neutrons 1 st shell with 2 electrons Second shell with only 4 electrons …has space for 4 more e- Atomic mass? 6 protons 6 neutrons 6 electrons = 12.011 (electrons negligible mass) 6 C 12.011 1H11H1

9. Relationships between atoms & molecules or, Bonds Interactions of outer shells or valence electrons Form molecules of multiple atoms Form compounds of multiple molecules

10. Covalent bonds –Atoms share electrons (e-) between pairs to satisfy each of their valence shells Example Ionic bonds –Unequally charged ions… e- transferred from one ion to another (gain/loss of e-) 1H11H1 17 Cl 35.4 11 Na 22 1H11H1 + +

11. Although the strongest bonds are Covalent, it is the weak Hydrogen bonds that are perhaps the most significant to cell functions. Polar molecules –Covalent bonds of unequal sharing (H 2 0) –O is more electronegative than H Hydrogen bonds include H Opposites (+ & -) attract creating H-bonds between water molecules

12. What else do we know about water? Naturally occurs in 3 forms with varying levels of energy and density. –Solid, liquid, gas Which is the most dense? Molecules in constant motion –Breaking & making H-bonds Varies with temperature, density, and dissolved particulates

13. Water is a common solvent that dissolves substances (solutes) to form an aqueous solution Additional water molecules dissociate leaving some hydrogen ions (H + ) and some hydroxide ions (OH - ) These ions are very reactive [H + ] in solution = acidic Therefore a lower pH [OH - ] in solution = basic Therefore a higher pH

14. The importance of Organic chemicals… (Ch. 3) contain at least one C atom –4 electrons in outer shell –in need of 4 more –covalent bonds with H, O, N, or other C Molecules of only C and H are called hydrocarbons Bonding determines shape Functional groups –determine properties & functions of organic compounds –Are usually polar, thus soluble in water, thus more reactive than carbon backbone by itself

15. Common Functional Groups

16. Most of a cells molecules are variations and extensions of a small set of small molecules. Making Macromolecules Many repeating smaller molecules Polymers of monomers Built by dehydration synthesis reaction (rxn)

17. Hydrolysis – breaking polymers

18. Classes of Macromolecules Carbohydrates –Simple & complex sugars –Monosaccharides & Polysaccharides Lipids –Fats, oils, waxes, etc. Proteins –Made of 20 Amino acids Nucleic Acids –DNA made of only 4 monomers (nucleotides)

19. Carbohydrates E.g. glucose, fructose, lactose, sucrose, starch, glycogen, cellulose… Fuel to do work Raw material for bigger molecules 2 sugars linked = disaccharide via dehydration synthesis More sugars = polysaccharides

20. Note: Animals can’t hydrolyze cellulose very well, therefore use bacteria to do it for us -- Byproduct is methane gas

21. Lipids Fats, oils, waxes, steroids Polymers of fatty acids and glycerol Energy storage molecules Hydrophilic heads (w / polar functional group(s); interacts easier with water) & hydrophobic tails (nonpolar; insoluble) Saturated fats –Very few double bonds –Lots of H’s –Solid at room temperature (butter, lard, and most animal fats) Unsaturated fats –Kinked due to double bonds, less H’s, take up more space –Liquid at room temperature –E.g. oils, margarine, and most plants fats –Hydrogenating unsaturated fats make them solid (margarine); trans fats

22. Steroids Lipids with backbones bent into rings Cholesterol –functions in digestion of fats –Important component in cell membranes (see ch 5) –Starting material of other steroids like sex hormones Note: Anabolic steroids (synthetics) mimic testosterone (see ch 12)

23. Proteins – have many roles Made from 20 different amino acids monomers Structural – hair, cell, cytoskeleton Contractile – muscles, motile cells Storage – sources of amino acids (egg whites) Defense – antibodies, membrane proteins Transport – hemoglobin, membrane proteins Signaling – hormones, membrane proteins Catalyst – free enzymes, membrane proteins

24. Protein properties… Amino group Carboxyl group Variable R group –Could be a single H –Or, C’s with functional groups –Determines specific properties and protein diversity

25. Nonpolar & hydrophobicPolar & hydrophilic are easier to dissolve in a cells aqueous solution

26. Linked to form polymer proteins by peptide bonds –Specific covalent bond between amino acids –Two aminos bonded = dipeptide –More aminos = polypeptides

27. Protein’s shape determines function 1 o structure: unique sequence of amino acids 2 o structure: coils or folds via H-bonding 3 o structure: 3-D globular or fibrous subunit via bonds of R-groups 4 o structure: multiple subunits

28. Nucleic Acids Polymers of 4 specific monomers = nucleotides –Via dehydration synthesis between sugars Builds chain w/sugar- phosphate backbone Single stranded RNA Double stranded DNA