Proteins
- Created by: Mazza24
- Created on: 23-11-15 21:13
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- Proteins
- contain the elements C,H,O,N,S
- are large polymers formed from amino acid sub-units.
- there are 20 different types of amino acids = infinite possible amino acid arrangements
- are large polymers formed from amino acid sub-units.
- shape
- function- is closely related to its shape
- determines the protein by the sequence of amino acids in the protein
- differences
- differ through having different R-groups
- Condensation
- With the loss of water peptide bonds are formed between the amino acids
- takes place between one of the amino group of the amino acids and the carboxyl group of another linking the carbon and nitrogen together
- two amino acids joined together form a dipeptide
- hydrolysis
- peptide bond can be broken with the release of the two constituent amino acids with the addition of water
- many amino acids joined together with peptide bonding= polypeptide
- protein structure
- Secondary
- amino acids in a poly peptide chains contain -NH and -C=O on either sides of the peptide bonds
- the O of the carboxyl gp, has a negative charge where as the N of this Amino gp, has a positive charge. This causes hyrdrogen bonds to form
- most common types:
- a-helic- hydrogen bonds are formed between the amino acids occuring at regular intervals. These hyrdogen bonds twist them into a spiral shape
- beta- pleated sheet
- more rigid and less flexible configurations than a-helix. formed by sections of the polypeptide chain into anti parallel directions lying adjacent to each other.
- hydrogen bonds form between -C=O and NH groups
- amino acids in a poly peptide chains contain -NH and -C=O on either sides of the peptide bonds
- Tertiary
- further folding of secondary structure - gives it its unique 3D shape
- consequence of a range of bonds formed between the R-groups of amino acids in the chain
- bonds
- hydrogen
- relatively weak and easily broken
- ionic
- formed between amino and carboxyl groups. are stonger than hydrogen bonds but are damaged by changes of pH
- disulphide
- colvanet bonds formed bwtween R-groups of sulfur containing amino acids. are very strong and are important in giving strength to structural proteins such as collagen.
- hydrogen
- further folding of secondary structure - gives it its unique 3D shape
- primary
- quarternary
- consist of two or more polypeptides bonded together
- some quarternary proteins contain non-protein components (prosthetic groups) that are intergranal in their function. These conjugated proteins include glycoprotein- is important in structure
- e.g. Haemoglobin
- Secondary
- types of protein
- fibrous
- consist of polypeptides arranged in chains that form fibres or sheets. these parallel chains are linked by cross-bridges to form very strong and stable molecule. are invariably structural in function.
- e.g. collagen - wound round each other and held together by hydrogen bonds. Collagen is found in tendons that link muscle to bone.
- consist of polypeptides arranged in chains that form fibres or sheets. these parallel chains are linked by cross-bridges to form very strong and stable molecule. are invariably structural in function.
- globular
- have a metabolic role and include enymes and antibodies. proteins ability to form very specific 3-D shapes is crucial to their role as enzymes and antibodies
- e.g. haemoglobin
- have a metabolic role and include enymes and antibodies. proteins ability to form very specific 3-D shapes is crucial to their role as enzymes and antibodies
- fibrous
- contain the elements C,H,O,N,S
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