Lecture 2 Cell chemistry

Levels of studying cells

• Level 1: Small organic molecules

• Level 2: macromolecules (Carbohydrates, Nucleic Acids, Proteins, Lipids)

• Level 3: Organelles

• Level 4: Cells

Important Biological Elements

• Hydrogen

• Carbon

• Nitrogen

• Oxygen

• Phosphorus

• Sulfur

Types of bonds

• Covalent

• Hydrogen

• Ionic

Bond energy

Amount of energy required to break a particular bond

Covalent bond

Valence electrons are shared between atoms

Valence electrons

Electrons in the outermost orbital/energy level of an atom. The electrons that form bonds wither other atoms

Octet rule

atoms are most stable with a total of 8 valence electrons (C,O, N, S)

Valence

The combining capacity of an atom. Relates to the number of single covalent bonds an atom can make

Hydrogen Bond

Forms between positive and negative partial charges

Polarity

an uneven distribution of charge within a molecule.

Water in Bio

Most important molecule in biological organisms

Properties of water that makes it essential for life

• Cohesive

• High temp. stabilizing capacity

• good solvent

Hydrophilic

“Water-Loviong” Good solutes in water becuase they are also polar. (sugar, organic acids, polar amino acids)

Hydrophobic

“Water-fearing” Bad solutes in water because they are nonpolar. (Lipids,nonpolar amino acids)

Ionic bond

Electrostatic interaction between charged atoms

Proton

hydrogen ion (H+)

pH

Related to the concentration of H+ in a solution, measure of acidity

pKA

Describes the tendency of a molecule to donate a proton. The higher the pkA, the more likely the molecule will be protonated. The lower pkA, the stronger the acid

functional group

Group of atoms within a molecule that has a characteristic chemical behavior

Negatively charged (Functional group)

• Carboxyl

• Phosphate

Positively charged (functional group)

• Amino

Neutral but nonpolar (functional groups)

• Hydroxyl

• Sulfhydryl

• Carbonyl

• Aldehyde

Oxidation

• Removal of electrons (Release energy)

Reduction

• Addition oof electrons (absorbs energy)

Gibbs free energy (G)

Available energy of a substance

Exergonic reaction

Energy is released (DeltaG is negative)(Spontaneous)

Endergonic reaction

Energy is absorbed (DeltaG is positive)(Non-spontaneous, requires energy input)

Enzyme(catalyst)

Lowers the energy required to carry out a reaction