Chemistry of macromolecules Flashcards
(30 cards)
What determines the properties of peptides and proteins?
The sequence of amino acids and their functional groups.
How are amino acids linked together?
By amide (peptide) bonds.
What is a zwitterion?
A molecule with both positive and negative charges, e.g., amino acids at their isoelectric point.
What does the isoelectric point refer to?
The pH at which an amino acid has a net zero charge.
Which group in amino acids acts as a Bronsted-Lowry base and under what conditions is it ionised
The amine group, ionises under acidic conditions and accepts a proton
Which group in amino acids acts as a Bronsted-Lowry acid and under what conditions is it ionised
The carboxyl group is ionised under basic conditions and donates a protein
Why is glycine unique among amino acids?
It is the only non-chiral α-amino acid.
What configuration do all protein amino acids have?
L-configuration (under CIP, mostly S-configuration except cysteine which is R). All are alpha which means you’re only one carbon away from carboxylic acid
What functional groups are on the side chains of amino acids?
Acidic, basic, neutral polar, neutral non-polar.
What determines protein solubility?
The surface composition of amino acids — polar/charged residues promote water solubility.
What restricts rotation in peptide bonds?
Resonance hybridisation.
What proteins are drug targets
Most drug targets are proteins with a three-dimensional shape. The strength of binding between a drug and a protein is determined by complementary functional groups and the shape of both molecules. (results in a stabilising interaction between both molecules)
What is the empirical formula of carbohydrates?
Cₙ(H₂O)ₙ.
What are the three main types of carbohydrates and give examples of them
Monosaccharides-glucose
disaccharide-maltose
polysaccharides-starch, glycogen
What is the main energy storage carbohydrate in mammals?
Glycogen.
What is cellulose used for and what is its structure
Cellulose: Structural material in plants paper straw cotton, homopolymer of glucose with β-1,4 links. Secondary structure held together by hydrogen bonds.
What is starch used for and what are the 2 kinds
Starch: Primary energy storage in plants, homopolymer of glucose. Amylose and amylopectin Multiple glucose to glucose bonds alpha 1-4 only in amylose. Amplopectin has some alpha 1-6 bond brances
How do monosaccharides exist in solution?
As cyclic hemiacetals in equilibrium with open-chain forms.
What are anomers?
Isomers of cyclic monosaccharides differing at the anomeric carbon.
What is mutarotation?
Interconversion between α- and β-anomers via the open-chain form.
What disaccharide is composed of glucose and galactose?
Lactose.
What disaccharide is composed of glucose and fructose?
Sucrose.
What kind of bonds are in starch and glycogen?
α-1,4’ and α-1,6’ glycosidic bonds.
What kind of bond is found in cellulose?
β-1,4’ glycosidic bonds.
