Proteins Flashcards
What are proteins?
Polymers made of monomers called amino acids
What is the bond formed in proteins?
Peptide bond
5 examples of proteins
Enzymes, cell membrane proteins, hormones, immunoglobulin, haemoglobin, keratin, collagen
How is a dipeptide created?
When 2 amino acids are linked together
What is a polypeptide?
When many amino acids are bonded together by peptide bonds the molecule formed is a polypeptide
What is the opposite of condensation reactions?
Hydrolysis
What are the four levels of protein structure?
Primary, secondary, tertiary and quaternary structure
What is the primary structure?
The sequence of amino acids in a polypeptide bonded by covalent peptide bonds
What is secondary structure?
Compact structure of protein molecule resulting from regular coiling or folding chain of amino acids
What are the 2 shapes that can form within proteins due to hydrogen bonds?
Alpha- helix and beta-pleated sheet
What is tertiary structure?
Compact structure of protein molecule resulting from 3D coiling of already folded chain of amino acids
What are the 4 bonds to keep folded proteins in precise shape
Hydrogen bonds, disulfide bonds, ionic bonds and weak hydrophobic interactions
What is quaternary structure?
3-D arrangement of two or more polypeptides or of a polypeptide and non-protein components such as haem in protein molecule
What is a globular protein?
They are compact, roughly spherical in shape and soluble in water. Their nonpolar hydrophobic R groups are orientated towards the center of the protein and their polar hydrophilic R groups orientate themselves on the outside of the protein.
What are fibrous proteins?
They are long strands of polypeptide chains that have cross linkage is due to hydrogen bonds
Example of globular protein
Haemoglobin, enzymes
Example of fibrous protein
Collagen, keratin
Describe haemoglobin structure and function
They are oxygen caring pigments in red blood cells. They have a quaternary structure. They contain four polypeptide chains and each chains are globin proteins.
What causes sickle cell anemia?
Glutamic acid (polar) in the surface of a beta chain is replaced with a valine (non-polar)
Each polypeptide chain contains _____ group
Haem
Structure of collagen
3 polypeptide chains held together by hydrogen bonds and some covalent bonds to form triple helix
Primary structure of collagen
Every 3rd amino acid is glycine
Function of collagen
Flexible structural proteins forming connective tissues and has great tensile strength
