AP Bio Exam Review: Biochemistry & Cells

Elements of Life 25 elements Hint: Remember CHNOPS 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 (dalton or AMU) Location Charge neutron 1 nucleus proton +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

Examples of Benefits to Life H2O Property Chemical Explanation Examples of Benefits to Life Cohesion polar H-bond like-like ↑gravity plants, trees transpiration Adhesion unlike-unlike plants xylem bloodveins Surface Tension diff. in stretch break surface bugswater Specific Heat Absorbs & retains E oceanmoderates temps protect marine life (under ice) Evaporation liquidgas KE Cooling Homeostasis Universal Substance Polarityionic Good dissolver solvent

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

Names & Characteristics 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

ie. amino acid  peptide  polypeptide  protein Monomers Polymers Macromolecules 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 larger smaller

Dehydration Synthesis (Condensation Reaction) Hydrolysis Make polymers Breakdown polymers Monomers  Polymers Polymers  Monomers A + B  AB AB  A + B + H2O + + H2O +

Differ in position & orientation of glycosidic linkage I. 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

II. Lipids Fats: store large amounts of energy saturated, unsaturated, polyunsaturated Steroids: cholesterol and hormones Phospholipids: cell membrane hydrophilic head, hydrophobic tail creates bilayer between cell and external environment Hydrophilic head Hydrophobic tail

Four Levels of Protein Structure: Primary Amino acid sequence 20 different amino acids peptide bonds Secondary Gains 3-D shape (folds, coils) by H-bonding α helix, β pleated sheet Tertiary Bonding between side chains (R groups) of amino acids H & ionic bonds, disulfide bridges 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 = Information Monomer: nucleotide IV. Nucleic Acids Nucleic Acids = Information Monomer: nucleotide DNA RNA 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 Visible light passes through specimen 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