Proteins 💪🏽 Flashcards
Describe the sub sections that make up a protein.
Monomer —> amino acid.
Dipeptide —-> two amino acids.
Polypeptide —-> more than two amino acids.
Protein —-> one or more polypeptide.
What is the chemical composition of an amino acid
Contains a central carbon.
Has two groups, an amino group and a carboxyl group.
Contains an R group which is a variable region where the amino acid changes from another and gives the amino acid its properties.
What is the second level of protein structure?
Secondary structure
chain starts to coil in sections—-> alpha helix
other sections fold into each other ——> beta pleated sheets
This is due to the hydrogen bonds between the amino group of one amino acid and the carboxyl group of another.
What happens when two amino acids join together?
Through a condensation reaction.
Hydrogen from the amino group and hydroxyl from the carboxyl group react together.
Form a peptide bond.
Loss of water.
What is the first level of protein structure?
Primary structure
initial polypeptide chain held together by peptide bonds.
What is the third level of protein structure?
Tertiary structure
More bonds start to form between different parts of the polypeptide chains.
Determines 3D shape of protein.
Done through the interaction of the amino acid R group as different R groups have different properties.
Can form hydrogen bonds/ ionic bonds.
Disulphide bonds are the strongest bonds and formed when two cysteine bonds interact.
What is the fourth level of protein structure?
Interactions between two or more polypeptide chains.
What are globular proteins?
Round/spherical, complex, 3D shapes which are water soluble because they have a hydrophilic R group on the surface of the protein to interact with water molecules.
Describe haemoglobin.
Made from 4 polypeptide subunits (2 alpha and 2 beta).
Function is to bind reversibly to oxygen to transport them to body tissues.
Each subunit contain the prosthetic group haem (conjugated protein).
Contains Fe2+ which binds to the oxygen.
Quaternary structure changes slightly to carry more oxygen.
Describe insulin
Globular protein which has 2 polypeptide bonds.
Held together by disulphide bonds.
Needed for the regulation of blood glucose concentrations.
Describe amylase.
Globular protein which catalyses the breakdown off starch.
Present in saliva.
Has single polypeptide chain.
Describe catalase.
Enzyme that catalyses the decomposition of hydrogen peroxide to water and oxygen.
Quaternary structure with four prosthetic haem groups. (Fe2+)
What is a fibrous protein?
Strong rod shaped protein, insoluble non complex 3D shape.
Structural roles in bones and tendons.
What is a conjugated protein?
Globular portion with a prosthetic group (non protein component)
Describe collagen.
Made by 3 polypeptide chains wound together to form a triple helix.
Large number of H-bonds form between polypeptide chains.
Stabilises quaternary structure of proteins and has strong cross links.
