AP Bio Unit 1

Water Polarity

Unequal electron sharing where highly electronegative.

Oxygen hogs electrons, creating partial positive and negative charges

Hydrogen Bond

An intermolecular attraction where the partial negative Oxygen of one water molecule attracts the partial positive Hydrogen of another

1. Water Polarity

Unequal electron sharing creating partial positive and negative charges.

1. Electronegativity of Oxygen

Oxygen strongly pulls shared electrons toward its own nucleus.

2. Hydrogen Bond

Weak attraction between a positive Hydrogen and a negative Oxygen of different molecules.

3. Cohesion

Water molecules sticking to each other via hydrogen bonds.

3. Surface Tension

Elastic layer on water's surface caused by cohesion.

4. Adhesion

Water molecules sticking to other polar surfaces like plant walls.

5. Capillary Action

Water climbing up narrow tubes against gravity using cohesion and adhesion.

6. High Specific Heat

Water's ability to resist temperature changes by absorbing or releasing massive heat.

6. Thermal Stabilization

Water buffering ecosystem temperatures because heat must first break hydrogen bonds.

7. High Heat of Vaporization

Immense heat energy required to turn liquid water into gas or vapor.

7. Evaporative Cooling

Cooling mechanism where hottest molecules evaporate, leaving cooler molecules behind.

8. Density of Ice

Ice floats because solid water is less dense than liquid water.

8. Crystalline Lattice

Rigid, spaced-out hexagon structure formed by hydrogen bonds when water freezes.

Universal Solvent

Water's ability to dissolve polar and ionic substances due to its partial charges.

Cohesion vs. Adhesion

Cohesion is water sticking to other water molecules; Adhesion is water sticking to different polar surfaces.

Capillary Action Mechanism

Adhesion clings to plant stem walls to climb upward, while cohesion pulls the remaining water column up along with it against gravity.

Cohesion vs. Adhesion

Cohesion is water sticking to other water molecules; Adhesion is water sticking to different polar surfaces.

Capillary Action Mechanism

Adhesion clings to plant stem walls to climb upward, while cohesion pulls the remaining water column up along with it against gravity.

-lysis

suffix meaning to split or break apart; to release

synthesis

to make something

polymer

many monomers bonded together

dehydration synthesis

a process where two molecules bond together and a molecule of water is released

hydrolysis

a process where a large molecule split into two or more smaller molecules by adding water to break bonds

monomer

building block or single unit of a polymer

Hydroxyl property

Polar group that bonds with water

Carboxyl property

Acidic group that charges amino acids negatively

Amino property

Basic group that charges amino acids positively

Sulfhydryl function

Protein stabilizer that forms disulfide bridges

Phosphate function

Negative group found in DNA and ATP

Methyl property

Nonpolar group that turns off genes

Water specific heat

Heat must first break hydrogen bonds before kinetic energy can increase temperature

Ice density

Freezing water expands into a spaced-out crystalline lattice making solid less dense than liquid

Dehydration synthesis

Covalent bonds are formed to link monomers into polymers by removing water molecules

Hydrolysis

Covalent bonds are cleaved to break polymers into monomers by adding water molecules

Starch vs. Cellulose

Starch uses alpha-glucose forming helical energy storage spirals while cellulose uses beta-glucose forming linear structural sheets

Saturated vs. Unsaturated fats

Saturated has straight hydrocarbon chains with no double bonds while unsaturated has kinked chains from carbon double bonds

Phospholipids

Amphipathic lipid with a hydrophilic phosphate head and hydrophobic fatty acid tails that forms bilayers

Amino acid R groups

Variable molecular chain that determines specific chemical properties (polar, nonpolar, ionic) to dictate tertiary folding

Primary Structure

Linear sequence of amino acids linked by covalent peptide bonds.

Secondary Structure

Local folding into alpha-helices and beta-pleated sheets stabilized by backbone hydrogen bonds.

Tertiary Structure

Overall 3D shape of a single polypeptide chain stabilized by R-group interactions.

Protein Denaturation

Loss of a protein's 3D shape and function due to heat or pH disrupting secondary, tertiary, and quaternary bonds while leaving the primary structure intact.

DNA vs. RNA Structure

DNA is double-stranded with deoxyribose and thymine; RNA is single-stranded with ribose and uracil.

Nucleic Acid Directionality

Polymerization occurs exclusively in the 5' to 3' direction because new nucleotides can only be added to the 3' hydroxyl (-OH) end.

Dissolution of Ionic Compounds

Water clusters around charged particles to form hydration shells, orienting partial-negative oxygens toward cations and partial-positive hydrogens toward anions.

Biological Buffer

A chemical system that maintains pH homeostasis by absorbing excess H+ ions in acidic conditions and releasing them in basic conditions