Biochemistry and Interactions Quiz

Study Notes

Biochemistry is the chemistry of life processes
Life on Earth is carbon-based (approximately 18.5% of human mass is carbon)
The six most important elements in biological compounds are C, H, O, N, P, S
Covalent bonds involve sharing electron pairs, and are the strongest type of bond between atoms.
Covalent bonds have specific valencies (number of bonds). For example, Carbon forms 4 bonds.

Ionic Interactions: Oppositely charged groups on molecules attract each other.
Hydrogen Bonds: partially positive hydrogen atoms attract partially negative atoms. Hydrogen bonds are ionic interactions between a partially positive hydrogen atom and a partially negative acceptor atom. The hydrogen bond acceptor is typically an oxygen or nitrogen atom.
van der Waals Interactions: Weak, attractive forces between molecules due to temporary fluctuations in electron distribution (temporary dipoles).

Electronegativity is the tendency of an atom to attract electrons towards itself.
Electronegativity increases across a row on the periodic table and decreases down a column. Electrons are attracted towards Oxygen (O) more than other elements. Electrons are less attracted towards Hydrogen (H).
- Electronegativity trend: O > N > S > C > P > H

Water molecules in aqueous solutions interact through hydrogen bonds.
Water is a versatile solvent (capable of dissolving many species).
Water can dissociate into H+ and OH− ions.
pH refers to the concentration of H+ ions. A neutral pH is 7.0
Acids release H+ ions into a solution, increasing H+ concentration and lowering pH.
Bases absorb H+ ions, reducing H+ concentration and raising pH.

Peptide Bonds: Form between amino acids.
Hydrophobic Amino Acids: Do not interact well with water. Structure includes examples (Glycine, Proline etc)
Polar Amino Acids: Interact well with water. Examples included (Serine, Tryptophan etc).
Positively Charged Amino Acids: Attractive to water (examples in the text, Arginine, Histidine).
Negatively Charged Amino Acids: Shown to be Hydrophilic (examples in the text, Glutamic Acid, Aspartic Acid).

Primary Structure: Linear sequence of amino acids.
Secondary Structure: Hydrogen bonding between peptide backbones causes regular folding patterns (alpha-helices and beta-sheets).
Tertiary Structure: Three-dimensional folding pattern of a protein that results from various side-chain interactions (e.g. hydrogen bonding, disulfide bonds).
Quaternary Structure: Larger proteins that are composed of two or more smaller polypeptide chains. Includes example proteins (Myoglobin & Haemoglobin).
Myoglobin: an example of a compact, globular protein that binds oxygen in the muscle.
Hemoglobin: example of a quaternary protein structure composed of four chains (2 α and 2 β chains).

Stereoisomers have the same atomic connectivity, but different spatial arrangements of atoms.
Enantiomers are chiral molecules that are mirror images of each other.