Proteins Flashcards
What are proteins
Proteins or polypeptides are macromolecules made up of unbranched chains of amino acids joined together via condensation reactions. Proteins allow for the manufacturing of enzymes, creation of hormones, development of tissue and fortifying the immune system.
Describe the structure of amino acids
It has an amino group that contains a Nitrogen biding to 2 hydrogens, a carboxyl group that contains carbon in a double bond with oxygen, and a single bond with oxygen that is bonded to a Hydrogen
There is also a side chain where carbon is bonded to hydrogen on one side and an R group on the other. The difference in the R group creates different amino acids.
How is glycine and alanine formed
Glycine is formed by swapping the R with Hydrogen
Alanine is formed b y swapping the R with CH3
How are peptide bonds formed
Peptide bonds are formed by the amine group on one amino acid undergoing a condensation reaction with the carboxyl group of another amino acid which also produces a molecule of water. The peptide bond is a covalent bond and links the C in the carboxyl group with the N in the amine group.
Describe the primary structure of proteins
The primary structure is the basic structure of amino acids in a chain. They have peptide bonds. It has a repeating sequence of N-C-C. The sequence of the amino acids determines the structural and biological properties of the protein.
What is the secondary structure of proteins
The secondary structure of proteins regular, recurring arrangements in space of adjacent amino acid residues in a polypeptide chain.
They consist of Alpha Helices and Beta pleated sheets. They bond via hydrogen bonding.
What are polypeptide chains
Polypeptide chains are polymers of amino acids joined together via peptide bonds
Describe the tertiary structure of proteins
The tertiary structure is the arrangement of the secondary structure into a 3-dimensional shape via complex folding. They bond via hydrogen, ionic and disulfide bonding, and hydrophobic interactions.
Describe the quaternary structure of proteins
The quaternary structure is when two or more polypeptides associate together to form a protein.They bond via hydrogen, ionic and disulfide bonding, and hydrophobic interactions.
Proteins can either be globular or fibrous. Describe these terms
Globular proteins are responsible for metabolic function are soluble in water as they have hydrophilic R groups on the surface and hydrophobic R groups internally in their center (e.g enzymes, hemoglobin)
Fibrous proteins serve a structural function and are not soluble in water (e.g. keratin and collagen)
Describe collagen
Collagen is made up of 3 polypeptide chains wound around one another in a triple helix held together by hydrogen bonds.Groups of the collagen molecule run parallel to each other to form fibrils that are then held together by covalent bonds to form fibers. Collagen has tremendous tensile strength which comes from fibers covalently bonding between lysine residues of adjacent fibers. The point where 1 molecule ends and another begins is staggered to avoid any weak points.
Describe haemoglobin
It is the oxygen-carrying respiratory pigment found in most animals. It forms compact spherical structures.
It is comprised of 4 polypeptide chains 2 Alpha globin chains and 2 Beta globin chains. It is formed into a compact shape and then linked to form the hemoglobin molecule.
It carries 4 oxygen molecules. The binding of the first oxygen is the hardest and it becomes easier for the 2nd to bind and that makes it easier for the 3rd to bind and that makes it easier for the 4th to bind.
Within the hemoglobin, the hydrophobic regions stay inwards to maintain the structure of the molecule and the hydrophilic regions stay outward to allow the molecule to be soluble in the cytoplasm of the red blood cells
