Protein structure Flashcards
proteins
polymers made of monomers called amino acids
monomers of polypeptides
monomers
how many amino acids are there
20
structure of amino acid
Central carbon atom bonded to:
- Amine
- carboxylic group
- hydrogen atom
- R group
bonds formed between amino acids
peptide bonds
peptide bonds
- covalent bonds
how do peptide bonds form
An -OH is lost from the carboxylic group of one amino acid and an H atom is lost from the amine group of another via condensation reaction
dipeptides
formed by the condensation of two amino acids
polypeptides
formed by the condensation of many amino acids
what happens during a hydrolysis reaction
peptide bond breaks with the addition of water, breaking it down to amino acids
primary structure
- sequence of amino acids in a polypeptide chain
- bonding: peptide bond
- determins proteins overall shape and function
secondary structure
- folding or coiling of the polypeptide chain into a- helixs or beta pleated sheets
- hydrogen bonds between -C=O group of one amino acid and the amine group of another
what does secondary structure forms
a-helix: coiled structure stabalized by hydrogen bonds
B- pleated: Zig zag pattern forming sheat-like structures
tertiary structure- definition
three-dimensional folding of a polypeptide, giving the protein its functional shape
tertiary structure bonding
- H bonds: weak between polar groups
- ionic bonds: oppositely charged R- groups
- Disulfide bonds: covalent between sulfur attoms
- Hydrophobic interactions: Nonpolar R groups clustering away from water
quaternary structure definition
arrangement of 2 or more polypeptide chains into functional protein
examples of quaternary structures
haemoglobin
collagen
haemoglobin
water-soluble globular protein
collagen
fibrous protein consisting of 3 polypeptide chains wound around each other
globular proteins
compact
roughly spherical
why do globular proteins form spherical shape when folding into their tertiary structure
- non polar R groups are oriented towards the centre of the protein, away from aqueous surroundings
- polar hydrophillic R groups oriente themselves towards the outside
globular proteins functions
physiological roles as they are easily transported around and are involved in metabolic reactions
haemoglobin structure
- polypeptide chains
- two alpha chains
- two beta chains - haem group
- 4 haem groups, that contain Fe2+ that binds to oxygen
collagen structure
- 3 polypeptide chains closely held together by hydrogen bonds to form a triple helix
- each of the 3 chains are coils
- hydrogen bonds form between the coils
- covalent bonds form cross-links between R groups of amino acids, in interacting triple helices
collagen function
- form structure of bones
- makes up cartilage and connective tissue
- prevents blood from bursting walls of arteries
- the main component of tendons
