Proteins Flashcards
(18 cards)
Proteins
Proteins are monomers made up of amino acids
Roles of protein in the body
Enzymes : biological catalysts that speeds up reactions
Antibodies: play a role in immune defense
Transport proteins and channel proteins: allows transport across cell membrane
Structural proteins: keratin found in hair and nails, collagen in connective tissues
How many types of amino acid is in the human body
20 types of amino acids, 11 can be synthesised by the body while 9 are essential and obtained from diet
Essential amino acids
Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine
Structure of amino acid
Amino group, carboxyl group, hydrogen and R group
Where does amino acids live
They live outside the cell in the cytoplasm
Glycine
R group- H
Serine
R group- CH2- OH
Alanine
R group- CH3
Aspartic acid
R group- CH2-C-OH=O
Polypeptide formation
Amino acids are joined together through condensation reactions where the water molecules is lost and forms a peptide bond
What is the reversible reaction of condensation reaction
Hydrolysis
Structural levels of proteins
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
Primary structure
It is a specific sequence of amino acids that forms a polypeptide chain
Secondary structure
Coils to form an alpha helix or folds to form a beta pleated sheets. It is held together by hydrogen bonds
Tertiary proteins
It could and folds further and it is held together by ionic bonds, disulphide bridges and hydrogen bonds
Quaternary structure
Proteins made up of two or more polypeptide chains. Contains essential functional groups known as prosthetic groups e.g haemoglobin contains haem group
The enzyme that breaks down proteins is called
Protease
