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

Atomic Structure Atom = smallest unit of matter that retains properties of an element Subatomic particles: Mass (dalton or AMU) LocationCharge neutron1nucleus0 proton1nucleus+1 electronnegligibleshell

Bonds CovalentIonicHydrogen All important to life Form cell’s molecules Quick reactions/ responses H bonds to other electronegative atoms Strong bond Weaker bond (esp. in H 2 O) 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

Polarity of H 2 O O - will bond with H + on a different molecule of H 2 O = hydrogen bond H 2 O can form up to 4 bonds

H 2 O PropertyChemical Explanation Examples of Benefits to Life Cohesion polar H-bond like-like ↑gravity plants, trees transpiration Adhesion H-bond unlike-unlike plants  xylem blood  veins Surface Tension diff. in stretch break surface H-bond bugs  water Specific Heat Absorbs & retains E H-bond ocean  moderates temps  protect marine life (under ice) Evaporation liquid  gas KE Cooling Homeostasis Universal Substance Polarity  ionic H-bond Good dissolver solvent

Solvent of life “like dissolves like” HydrophilicHydrophobic Affinity for H 2 OAppears to repel Polar, ionsNonpolar Cellulose, sugar, saltOils, lipids BloodCell 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 GroupMolecular FormulaNames & CharacteristicsDraw an Example Hydroxyl-OHAlcoholsEthanol Carbonyl>CO Ketones (inside skeleton) Aldehydes (at end) Acetone Propanol Carboxyl-COOH Carboxylic acids (organic acids) Acetic acid Amino-NH 2 AminesGlycine Sulfhydryl-SHThiolsEthanethiol Phosphate-OPO 3 2- / -OPO 3 H 2 Organic phosphatesGlycerol phosphate

MonomersPolymersMacromolecules Small organic Used for building blocks of polymers Connects with condensation reaction (dehydration synthesis) Long molecules of monomers With many identical or similar blocks linked by covalent bonds Giant molecules 2 or more polymers bonded together ie. amino acid  peptide  polypeptide  protein smaller larger

Dehydration Synthesis (Condensation Reaction) Hydrolysis Make polymersBreakdown polymers Monomers  PolymersPolymers  Monomers A + B  ABAB  A + B + H 2 O + +

Carbohydrates Fuel and building Sugars are the smallest carbs  Provide fuel and carbon monosaccharide  disaccharide  polysaccharide Monosaccharides: simple sugars (ie. glucose) Polysaccharides:  Storage (plants-starch, animals-glycogen)  Structure (plant-cellulose, arthropod-chitin) Differ in position & orientation of glycosidic linkage

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

Nucleic Acids Nucleic Acids = Information Monomer: nucleotide DNARNA Double helix Thymine Carries genetic code Longer/larger Sugar = deoxyribose Single strand Uracil Messenger (copies), translator tRNA, rRNA, mRNA, RNAi Work to make protein Sugar = ribose

Comparisons of Scopes Light Visible light passes through specimen Light refracts light so specimen is magnified Magnify up to 1000X Specimen can be alive/moving color Electron 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

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