ionic bonding
occurs when a metal lose electrons and becomes positively charged. non-metals gain those electrons and become negatively charged
the two opposite charges come together to form an ionic bond
covalent bonding
occurs when two non-metals share electrons
two types of covalent bonding
2
polar covalent: unequal sharing between electrons
non-polar covalent: equal sharing between electrons
hydrogen bonding
2
- strongest van der waals forces and most biologically significant
- forms between H and one other molecule such as N, O, F
glycosidic linkage
2
- carbs
- joins the monosaccharides into larger carbohydtates
(disaccharides and polysaccharides)
peptide bond
3
- proteins
- covalent bond between the amino group and carboxyl group of 2 amino acids
- When the carboxyl group of one amino acid is next to the amino group of the another amino acid, a dehydration (or condensation) reaction will join them together with a peptide bond.
phosphodiester bond
2
- nucleic acid
- 2 strands composed of repeated nucleotide subunits
ester bond
2
- fats
- When a glycerol molecule reacts with fatty acids, a condensation (or dehydration) reaction occurs between the hydroxyl (-OH) and carboxyl (-COOH) functional groups
dehydration/condensation reactions
Used by cells to synthesize larger molecules.
hydrolysis
2
- Opposite of a dehydration reaction
- Water (H2O) is the reactant that splits the molecule into smaller subunits.
primary structure
2
- specific linear sequence of amino acids.
- If one amino acid is changed in the sequence, it could render the protein dysfunctional.
secondary structure
3
- folds and coils at various locations of polypeptide due to hydrogen bonding in
the polypeptide backbone. - β-pleated sheet - 2 parallel polypeptide chains joined to one another by hydrogen bonds
- α-helix: Hydrogen bonding between every fourth amino acid, creating a coil shape Ex. keratin = fibrous protein in hair
tertiary structure
3D structure is determined by intermolecular reactions between R-groups in the
polypeptide chain.
quarternary structure
some proteins consist of 2 or more polypeptide chains aggregated into one functional macromolecule
denaturation
3
- Enzymes are proteins
- However, if pH, [salt], temperature, etc. in the environment are altered, the protein may unravel or change shape
- When a protein changes shape no longer carries out its original function
activation energy
2
- All chemical reactions require energy in order to take place.
- Enzymes (catalysts) work by lowering the activation energy of chemical reactions
cofactors: inorganic
Non-proteins (often metals like Fe, Cu, Zn & Mn) that can bind to an enzyme and are essential for the catalytic activity of the enzyme that they bind to
coenzymes: organic
responsible for shuttling molecules from one enzyme to another
competitive inhibitors
Similar in structure to the substrate and are able to bind with the active site and block the normal substrate from binding
noncompetitive inhibitors
Attach to a different site on the enzyme which changes its shape causing the substrate to not bind properly
allosteric regulation
5
- Allosteric regulation can either inhibit or stimulate enzyme activity
- There are regulatory molecules that can bind to a different site than active site called the allosteric site
- When a regulatory molecule binds to the allosteric site it also changes the shape of the active site
- If an allosteric activator binds to the allosteric site, the enzyme will stay functional and stimulate the chemical reaction
- If an allosteric inhibitor binds, the enzyme changes shape and enzymes inactive form is stabilized and will not bind any substrate
hydrophobic interactions
non-polar side groups cluster together
disulfide bridges
formed between the –SH groups of 2 cysteine amino acids that react to form an S-S covalent bond. This is a strong bond that holds the 3D shape of the protein.
intermolecular forces
Intermolecular reactions include:
Ionic bonds, Hydrophobic interactions, Disulfide bridges
