Mucus layer on the surface of the epithelial cells is sticky because it has less water than normal, this is because of less salt & water transport caused by a faulty protein channel. PROTEIN STRUCTURE:
Antibodies, enzymes and many hormones are all protein molecules. Proteins also have functions within a membrane.
Proteins are composed of amino acids, there are 20 different amino acids that occur in proteins.
All amino acids contain an amine group -NH, a carboxylic acid group -COOH, and a hydrogen -H attached to central carbon atom C, however each amino acid has a different R group which determines the amino acid properties. PRIMARY STRUTURE:
The sequence of amino acids in the polypeptide chains are known as a primary structure of a protein.
Two amino acids joined in a condensation reaction form a dipeptide, with a peptide bond forming. This process can be repeated to form polypeptide chains which can contain thousands of amino acids.
A protein is made by one or more of these polypeptide chains. SECONDARY STRUCTURE:
Interactions between the amino acids in the polypeptide chains cause the chain to twist and fold into a three dimensional shape.
Lengths of the chain may first coil together into a-helices or come together in B-pleated sheets. TERTIARY &QUATERNARY STRUTURE:
Chemical bonds and hydrophobic interaction between are groups maintain this final tertiary structure of the protein.
And are group is polar when the sharing of a electrons is not quite even.
Polar are groups attract other polar molecules, like water, and therefore hydrophilic
None polar groups are hydrophobic.
A protein made up of several polypeptide chains held together e.g. haemoglobin is made up of four polypeptide chains . only protein with several polypeptide changes have a quaternary structure. Single chain proteins stop at a tertiary level. CONJUGATE PROTEINS:
Conjugated proteins have another chemical group associated with their polypeptide chains
Globular and Fibrous Protein:
Protein can be divided into two groups.
the polypeptide chain folded into a combat ball shape the proteins are soluble due to the hydrophilic chains therefore important in metabolic reactions.
Enzymes are globular proteins there tree dimensional shape is important to their roles in binding to other substances. FIBROUS PROTEINS:
Remain as long chains.