Midterm Final Review
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AP Bio Exam Review: Biochemistry & Cells Elements of Life • 25 elements • 96% : C, O, H, N • ~ 4% : P, S, Ca, K & trace elements (ex: Fe, I) Hint: Remember CHNOPS II. Atomic Structure • Atom = smallest unit of matter that retains properties of an element • Subatomic particles: Mass Location Charge (dalton or AMU) neutron 1 nucleus 0 proton 1 nucleus +1 electron negligible shell -1 Bonds Covalent Ionic Hydrogen All important to life Form cell’s molecules Quick reactions/ responses H bonds to other electronegative atoms Strong bond Weaker bond (esp. in H2O) Even weaker Made and broken by chemical reactions Weaker Bonds: Van der Waals Interactions: slight, fleeting attractions between atoms and molecules close together – Weakest bond – Eg. gecko toe hairs + wall surface 1. Polarity of H2O • O- will bond with H+ on a different molecule of H2O = hydrogen bond • H2O can form up to 4 bonds H2O Property Chemical Explanation Examples of Benefits to Life Cohesion •polar •H-bond •like-like ↑gravity plants, trees transpiration Adhesion •H-bond •unlike-unlike plants xylem bloodveins Surface Tension •diff. in stretch •break surface •H-bond bugswater Specific Heat •Absorbs & retains E •H-bond oceanmoderates temps protect marine life (under ice) Evaporation •liquidgas •KE Cooling Homeostasis •Polarityionic Good dissolver Universal Substance 4. Solvent of life • “like dissolves like” Hydrophilic Hydrophobic Affinity for H2O Appears to repel Polar, ions Nonpolar Cellulose, sugar, salt Oils, lipids Blood Cell membrane Acids and Bases Acid: adds H+ (protons); pH<7 Bases: removes protons, adds OH-; pH>7 Buffers = substances which minimize changes in concentration of H+ and OH- in a solution (weak acids and bases) • Buffers keep blood at pH ~7.4 • Good buffer = bicarbonate Figure 3.9 The pH of some aqueous solutions Functional Groups Functional Group Molecular Formula Names & Characteristics Draw an Example Hydroxyl -OH Alcohols Ethanol Carbonyl >CO Ketones (inside skeleton) Aldehydes (at end) Acetone Propanol Carboxyl -COOH Carboxylic acids (organic acids) Acetic acid Amino -NH2 Amines Glycine Sulfhydryl -SH Thiols Ethanethiol Phosphate -OPO32- / -OPO3H2 Organic phosphates Glycerol phosphate Monomers •Small organic •Used for building blocks of polymers •Connects with condensation reaction (dehydration synthesis) Polymers Macromolecules •Long molecules of •Giant molecules monomers •2 or more polymers •With many identical bonded together or similar blocks linked by covalent bonds ie. amino acid peptide polypeptide protein smaller larger Dehydration Synthesis (Condensation Reaction) Hydrolysis Make polymers Breakdown polymers Monomers Polymers Polymers Monomers A + B AB AB A + B + + H2O + H2O + I. Carbohydrates • Fuel and building • Sugars are the smallest carbs Provide fuel and carbon • monosaccharide disaccharide polysaccharide • Monosaccharides: simple sugars (ie. glucose) • Polysaccharides: Differ in Storage (plants-starch, animals-glycogen) Structure (plant-cellulose, arthropod-chitin) position & orientation of glycosidic linkage II. Lipids A.Fats: store large amounts of energy – saturated, unsaturated, polyunsaturated B.Steroids: cholesterol and hormones C.Phospholipids: cell membrane – hydrophilic head, hydrophobic tail – creates bilayer between cell and external environment Hydrophilic head Hydrophobic tail Four Levels of Protein Structure: 1. Primary – Amino acid sequence – 20 different amino acids – peptide bonds 2. Secondary – Gains 3-D shape (folds, coils) by H-bonding – α helix, β pleated sheet 3. Tertiary – Bonding between side chains (R groups) of amino acids – H & ionic bonds, disulfide bridges 4. Quaternary – 2+ polypeptides bond together amino acids polypeptides protein • Protein structure and function are sensitive to chemical and physical conditions • Unfolds or denatures if pH and temperature are not optimal IV. Nucleic Acids Nucleic Acids = Information Monomer: nucleotide DNA •Double helix •Thymine •Carries genetic code •Longer/larger •Sugar = deoxyribose RNA •Single strand •Uracil •Messenger (copies), translator •tRNA, rRNA, mRNA, RNAi •Work to make protein •Sugar = ribose Comparisons of Scopes Light Electron • Visible light passes through specimen • Light refracts light so specimen is magnified • Magnify up to 1000X • Specimen can be alive/moving • color • Focuses a beam of electrons through specimen • Magnify up to 1,000,000 times • Specimen non-living and in vacuum • Black and white Prokaryote Vs. Eukaryote • • • • • “before” “kernel” No nucleus DNA in a nucleoid Cytosol No organelles other than ribosomes • Small size • Primitive • i.e. bacteria • “true” “kernel” • Has nucleus and nuclear membrane • Cytosol • Has organelles with specialized structure and function • Much larger in size • More complex • i.e. plant/animal cell Parts of plant & animal cell p 108-109 • Cells must remain small to maintain a large surface area to volume ratio • Large S.A. allows increased rates of chemical exchange between cell and environment Animal cells have intercellular junctions: • Tight junction = prevent leakage • Desomosome = anchor cells together • Gap junction = allow passage of material Cell Membrane 6 types of membrane proteins Passive vs. Active Transport • Little or no Energy • Moves from high to low concentrations • Moves down the concentration gradient • i.e. diffusion, osmosis, facilitated diffusion (with a transport protein) • Requires Energy (ATP) • Moves from a low concentration to high • Moves against the concentration gradient • i.e. pumps, exo/endocytosis hypotonic / isotonic / hypertonic Exocytosis and Endocytosis transport large molecules 3 Types of Endocytosis: • Phagocytosis (“cell eating” solids) • Pinocytosis (“cell drinking” fluids) • Receptor-mediated endocytosis • Very specific • Substances bind to receptors on cell surface
