AP Bio Exam Review: Biochemistry & Cells

Elements of Life 25 elements Hint: Remember CHONPS 96% : C, O, H, N ~ 4% : P, S, Ca, K & trace elements (ex: Fe, I) Hint: Remember CHONPS

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 Solvent 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

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

Surface Area and Volume What is the SA/V for this cell? Round your answer to the nearest hundredths.

Solution SA= 4 r2 =4(3.14) 52 =314 Volume of a sphere= 4/3 r3 =4/3 (3.14)53 =523.33 SA/V=314/523.33 =.60

Water Potential and Solution Potential Solute potential= –iCRT i = The number of particles the molecule will make in water; for NaCl this would be 2; for sucrose or glucose, this number is 1 C = Molar concentration (from your experimental data) R = Pressure constant = 0.0831 liter bar/mole K T = Temperature in degrees Kelvin = 273 + °C of solution Sample Problem The molar concentration of a sugar solution in an open beaker has been determined to be 0.3M. Calculate the solute potential at 27 degrees celsius. Round your answer to the nearest tenths.

Solution Solute potential= –iCRT -i= 1 C= 0.3 R = Pressure constant = 0.0831 T= 27 +273=300K Solute potential = -7.5

Water Potential Practice  Four bags made from dialysis tubing were filled with a sucrose solution. Each bag was then immersed in four beakers containing sucrose solutions of 0.2M, 0.4M, 0.6M, and 0.8M. After 30 minutes, each bag was weighed and its change in weight was calculated. All solutions were at 25°C. The results are shown in the following graph: Determine the solute potential of the dialysis bag to the nearest tenth.  

Solution To find the solute potential of the dialysis tubing, look for 0g change in mass. That will indicate that the two solutions are isotonic. 0.7M

pH concentration What is the hydrogen ion concentration of a solution of pH 8? Round to the nearest whole number

[H+] if pH = 8.0 [H+] = 10-pH [H+] = 10-8.0 1÷10⁸ = 0.00000001 Solution [H+] if pH = 8.0 [H+] = 10-pH [H+] = 10-8.0 1÷10⁸ = 0.00000001

pH concentration pH scale is from 0-14 The pH and pOH values add to 14 Each pH unit is 10x the difference How many times greater is the H+ ion concentration of pH 3 solution compared to a pH 6 solution? A solution with a pH of 4 has a hydrogen concentration of 10-4, what is its hydroxide concentration?

Solution pH 3 is 1000x more concentrated than pH 6 Hydroxide concentration = 10-10

Dilution Joe has a 2 g/L solution. He dilutes it and creates 3 L of a 1 g/L solution. How much of the original solution did he dilute? Round to the nearest tenths.

Solution We are looking for V1: C1v1= C2V2 2V1 = 1(3) V1= 1.5