3.1.4.1 General Properties of Proteins Flashcards
what are proteins also referred to as?
polypeptides
what are polypeptides made from (ie. monomers?)
amino acids
how many amino acids are there and how many of these are naturally occurring?
100 identified, 20 of which are naturally occuring
describe the general structure of an amino acid and draw it
(check diagram against notes)
amine group (NH₂)
carboxyl group (COOH)
central carbon (C)
hydrogen atom (H)
R group (R)
what can 2 amino acids bond together to form and which mechanism does this involve?
two amino acids can bond together to form a dipeptide, and this happens through a condensation reaction, (molecule of H₂O removed and a bond is made.)
what sort of bond is formed when a dipeptide is made and where is it?
peptide bond forms between the C-N
if condensation reactions are repeated after a dipeptide then what is formed?
polypeptide
place in order of decreasing strength: ionic, hydrogen, covalent bonds
STRONGEST
covalent
ionic
hydrogen
WEAKEST
give 3 examples of tertiary proteins
enzymes, antibodies and hormones
give 4 examples of quaternary proteins and 2 of their prosthetic groups (PG)
chlorophyll (PG = Mg)
haemoglobin (PG = Fe)
collagen
antibodies
what is an R group?
an R group is a carbon containing side chain
it is what differs between amino acids
state the 5 functions of polypeptides within an organism and give examples
- STRUCTURE eg. collagen, keratin, actin
- ENZYMES eg. carbohydrase, protease
- TRANSPORT eg. haemoglobin
- HORMONES eg. oestrogen, testosterone
- ANTIBODIES
name and describe the chemical test for proteins
BIURET TEST:
- place sample of solution into test tube
- add equal volume of sodium hydroxide
- add few drops of copper (II) sulphate
- mix gently
+ve result = purple/mauve
-ve result = remains blue
describe the differences between globular and fibrous proteins
fibrous: elongated shape, insoluble, structural roles eg. collagen, keratin, myosin, actin
globular: spherical shape, soluble in water, metabolic roles eg. haemoglobin, enzymes, hormones
describe the primary structure of a protein (3 points)
- a singular polypeptide chain
- only contains peptide bonds
- the order and number of amino acids in the chain determines the structure and function of a protein