Biology: Water Properties, Enzymes, Macromolecules, and Cell Transport

Polar Molecules

The water molecule is polar.

Hydrogen Bonds

When hydrogen atom is part of a polar molecule, hydrogen atom has slight +charge making it attracted to -charged atom.

Properties of Hydrogen Bonds

20 times weaker than typical covalent bonds.

Cohesion

Attraction among molecules of substance makes water molecules stick together to form surface tension.

Adhesion

Attraction among molecules of different substances water molecules can stick to each other or to sides of glass tube.

H2O as a Solvent

Water dissolves polar molecules.

Properties of H2O

High specific heat, high heat vaporization, cohesion, adhesion, less dense as solid compared to liquid.

Acid

A compound that releases a proton (hydrogen ion) when dissolved in water.

Base

Removes H ions from a solution.

pH Scale

0-6 Acidic, 7 neutral, 8-14 basic.

Endothermic Reaction

Higher bond energy (takes more energy to break the bonds); energy is absorbed to make a difference.

Exothermic Reaction

Releases more energy than it absorbs; products have lower bond energies than reactants.

Enzyme

A catalyst used in living organisms that are involved in both breaking down food molecules and building new proteins.

Lock and Key Model

The model of an enzyme that allows a certain reactant to bind to it.

Co-factors

Non-chemical compounds that enzymes require for activity.

Coenzyme

A cofactor that is exclusively organic and acts as temporary carriers of chemical energy between enzymes.

Atoms

Every physical thing you can think of, living or not, is made of incredibly small particles.

Carbohydrates

Functions: producing and storing short term energy; Structure: formed in chains with groups and rings; Elements: Carbon, Hydrogen, Oxygen.

Proteins

Functions: Storage (Albumin), Transport (Hemoglobin), Regulatory (Hormones), Movement (Muscles), Structural (Membranes, hair, nails), Enzymes (Cellular Reactions); Elements: C, H, O, and N.

Nucleic Acids

Functions: DNA (storage of genetic information), RNA (Transfers genetic code to make proteins), ATP (Cellular energy); Elements: Phosphate group, Nitrogenous Base, SC sugar.

Lipids

Functions: Long term energy storage, Protection vs. heat loss (insulation), Protection against physical shock, Protection against water loss, Chemical Messengers (Hormones), Major components of membranes; Elements: Carbon, Hydrogen, and Oxygen.

Passive Transport

Movement of molecules without the use of ATP.

Diffusion

Movement of molecules; substances are not soluble in lipids and must have help; affected by size of molecules, size of concentration gradient, and temperature.

Facilitated Diffusion

Passive and doesn't take energy; helps diffusion by creating a protein channel that only glucose can go through.

Osmosis

Diffusion of water molecules across a semi-permeable membrane; high to low.

Active Transport

The process of moving materials into or out of the cell that requires energy.

Endocytosis

The process of taking material into the cell.

Exocytosis

Process of expelling materials from the cell.