Session 2: Biological compounds and functional groups Flashcards
Distinguish between the major types of small biomolecules and larger polymeric compounds.
- Amino acids
- Simple carbohydrates
- Nucleotides
- Lipids - a collection of hydrophobic molecules
Define aliphatic and aromatic compounds.
Aliphatic compounds: C-C chains that are straight, w/ or w/o branches, w/ single or double bonds.
Aromatic compounds: C-C structures that form a ring.
Name the 7 major functional groups.
- Hydroxyl group
- Carbonyl group
- Ketone group
- Aldehyde group
- Carboxyl group
- Amino group
- Sulfhydryl group
Explain the notion of groups that carry a charge.
Acidic groups can dissociate, leaving the deprotonated remainder of the molecule w/ a negative charge.
Compounds carrying nitrogen are usually basic, the nitrogen can accept a proton and thereby acquire a positive charge.
List two major acidic groups in the body.
- Carboxylic acids
2. Phosphoric acids
Explain a phosphoryl group.
A derivative of phosphoric acid.
Explain when nitrogen will carry a positive charge.
When the 2 electrons from the nitrogen lone pair form a covalent bond w/ a proton, one of the electrons “is moving away from the nitrogen” and the nitrogen atom carries a positive charge.
Describe a polar covalent bond.
A bond formed when the electron pair linking the atoms is shared unequally.
Indicate the charge NH3 is carrying.
Positive.
Indicate the charge -C-NH2 is carrying.
Partial negative charge (polarised but no charge).
Distinguish when a compound is soluble.
A compound will be soluble when it contains charged or polar bonds that associate with partial positive or negative charges of water.
Give a definition for a hydrophilic group/ molecule.
Polar compounds that have the ability to interact with water molecules by dissolving in an aqueous environments like blood or ICF.
Give two examples of hydrophilic compounds.
- -OH group
2. -NH2 group
Give a definition for a hydrophobic group/ molecule.
Compounds that are non-polar and cannot be attracted to partially negative and partially positive charges on water molecules and are therefore water insoluble.
Explain the term lipophilic compound.
Nonpolar compounds that readily dissolve in nonpolar fat.
Give a definition for an amphipathic compound and give 2 examples.
A molecule that has both polar and nonpolar regions.
Examples: Phospholipids and bile salts
Give two ways in which functional groups play a role in the reactivity of molecules.
- The partial charges on polar compounds determine the course of biochemical reactions. The more polar the bond, the weaker it is and the easier it is to break it. E.g, the carbonyl group accounts for many carboxylic acid reactions,
- The negative charge of the COO - H+ acidic group attracts to positive charges on other compounds and thereby play a role in the formation of new derivatives.
Explain the two steps that take place during fatty acid activation.
Step 1: ATP reacts with fatty acid
Step 2: Reaction with coenzyme A which produces an activated fatty acid with a high energy thioester bond
Explain the role of ATP in the activation of fatty acids.
It reacts with the fatty acid to form an adenosine monophosphate (AMP) derivative.
Define phosphorylation as as an example of a group transfer reaction.
- A reaction where a phosphate group is transferred from a phosphorylated compound to a hydroxyl group on the other compound.
- The source of the phosphate group is often ATP, not always
- The phosphorylation of glucose is is catalysed by hexokinase
- The purpose of phosphorylating glucose in a cell is to create a flow gradient
- Another purpose of phosphorylating sugars is to join them to nucleosides - a method for transferring sugars to form macromolecules
Explain why a peptide bond is an example of a condensation reaction.
Its formation involves the removal of the water molecule.
Briefly explain what a rearrangement reaction is.
A rearrangement of internal bonds converts one type of molecule into a different molecule.
Briefly explain what triose phosphates are.
A phosphoric ester.
