PROTEINS & ENZYMES Flashcards
what are proteins?
proteins are functional units of the cell
what do proteins form?
enzymes, structural, transport, storage, signalling, receptors, gene regulation
what links monomers to form polymers?
dehydration reaction - forming peptide bonds between 2 amino acid monomers
how many amino acids make up a proteins?
20
what determines the structure and function of the protein?
side-chain R of the protein
what makes up a protein?
variable side chain (R group), Carboxyl group, Hydrogen atom and amino group
how does protein name come about?
by the two primary functional groups
how many essential and non-essential amino acid are there?
essential : 9 - cannot be synthesized by body
non-essential : 11 - can be synthesized by body
what are the functional group?
gives the molecule the properties and are centres of chemical reactivity
what are proteins composed of?
C, H, O, N & small amounts of other elements notably sulfur
what are the level of structures?
primary, secondary, tertiary, quarternary
what are primary structures?
linear order of amino acid joined together by as polypeptide
what are secondary structures?
localised folding of linear polypeptide resulting in alpha helix or beta pleated sheet or random loop
what are tertiary structures?
3d shape of a protein which closely links to its function
what are quarternary structures?
made up of 2 or more subunits of proteins
what are peptides and polypeptide?
peptide : 2 or more amino acids linked
polypeptide : chain of amino acids joined by peptide bonds
what determines amino acid sequence?
the genes - number and sequences of amino acid vary in proteins
what happens during secondary structure?
chemical and physical interactions causes the polypeptide chains to be folded or pleated into different shapes by hydrogen bonding between amino acids
what r group interactions contribute to tertiary structure?
hydrogen, ionic, disulphide bonding, hydrophobic interactions and van der waal’s force
what happens in quarternary structure?
the individual polypeptides join together to form a larger protein - all subunits must be present for protein to function
what causes protein to denature?
pH or heat cause irreversible change in protein shape
what are enzymes?
proteins which acts as a catalyst to speed up a chemical reaction
what does enzymes have?
enzymes have an active site where the substrate binds
what are substrates?
the molecules that an enzyme work on
what can enzymes do?
either break a single structure or join two or more substrate molecules together
what are the two mechanism of enzyme action?
lock and key - substrate must be compatible so that enzymes can modify the substrates
induced fit hypothesis - enzyme will mold itself to the shape of the molecule once the proper substrates makes contact with the enzyme
properties of an enzyme?
- all enzymes are proteins
- speed up biochemical reactions
- very specific (substrate-specific)
- lowers activation energy by lowering energy barrier allowing the reactants to react faster forming the products
- not damaged during the reaction - can be reused
what do some enzymes require?
cofactors - required in diet of organisms
factors that affect the rate of enzyme reaction?
temperature - must hit optimum temp ; high temp breals the disulphide bonds holding the tertiary structure - DENATURED
pH - must reach optimum pH (5-9)
substrate concentration - directly proportional at the start and no effect nearing the end as all enzymes are working at max. rate
enzyme concentration - directly proportional all the way if substrates are in excess
enzyme inhibitors - active enzymes is prevented from combing with its substrate
what type of enzyme inhibitors are there?
IRREVERSIBLE - Inhibitors are temporarily bound
REVERSIBLE - competitive and non-competitive
- Inhibitors bind permanently, permanently deactivating the enzyme
competitive inhibition
inhibitor competes with the substrate for the active site
non-competitive inhibition
inhibitor binds to the allosteric site and alters its shape
