Studied by 5 people
Catalyst
A substance that increases the rate of a chemical reaction. Eg. MnO2
Enzyme
Biological catalysts made by living ells, used for reactions that would proceed too slowly at cellular temperature to sustain life processes. Eg. Digestion
Substrate
Reactants converted to products in enzymes
Outline the structure and function of globular proteins
Have precise tertiary or Quaternary structure so that the folds of the peptide allow certain amino acid side chains to form an active site.
Outline the structure of active sites
Active sites are where substrates bind to be converted into products, typically close to the surface of the enzyme. Has a 3D shape and chemical proteins that match the substrate. Creating specificity for enzymes and substrates, so they vary in size.
Outline the function of active site
Catalyze reactions quickly and release products, so that some enzymes can perform thousands of reactions. If altered by environment or chem changes, results in loss of catalytic function.
Outline cyclical pathways
Chemical transformations in metabolic pathways happen in small steps. Occurs in nine steps, each catalyzed by a different enzyme to convert glucose into pyruvate.
Anabolic Reactions
Reactions that build large larger molecules from smaller ones, requires energy input.
Catabolic Reactions
Reactions that generally break down large molecules into smaller ones, releasing energy.
Transition state
Intermediate stage during which reactant/substrate bonds are being broken, while product bonds are beginning to form.
Activation energy
Energy input required to react the transition state in a chemical reaction
Exothermic
Chemical changes that result in a net release of energy as new bonds are made
Exergonic
Chemical changes that result in a release of energy used to do work. Eg. Use of ATP in a pump protein
Endergonic
Chemical changes that store energy in another molecules eg. making ATP
Outline the functions of heath from metabolic reactions
Heat is used to maintain a body temperature higher than the environment in bird and mammals. Can sometimes require cooling mechanisms such as perspiration.
Enzymes-substrate specificity
The ability of an enzyme’s active site to bind certain substrate molecules but not others.
Define Absolute Enzyme specificity
Specificity to only one substrate.
Define Broad Enzyme specificity
Works on multiple substrates.
Define Denaturation
Small disruptions to an enzyme’s property or shape resulting in the loss of function.
State the function of non-substrate molecules in an allosteric site
These molecules cause an increase or decrease in activity of the enzyme by changing the shape of its active site.
Outline Competitive inhibitors
Somewhat resemble substrates, but cannot be broken down by the enzyme. The temporarily bind to the active site, which blocks substrate molecules from being able to bind, resulting in slowed enzyme activity.
Outline level of inhibition
Relative to the ratio of an inhibitor to a substrate. As substrate concentration increases, inhibition decreases because the likelihood of substrate arriving at the active site before the inhibitor becomes higher. However non-competitive inhibitors stay effective at high substrate concentration due to their allosteric site.
Outline feedback inhibition
Enzyme inhibition is part of the bigger picture of regulating the different pathways of metabolic reactions. Regulation ensures that enough necessary products are produced.
Define end product
Often an intermediate/product towards the end of a pathway acting as an allosteric inhibitor of an enzyme early in the pathway.
Outline irreversible inhibition
Usually bond covalently to an active site, permanently stops its function.
Define mechanism-based inhibitors
Can be specific to an enzyme, where the inhibitor resembles the substrate. Considered to be toxic to biological systems
Outline Mechanism-based inhibitors
Can be lethal if the enzyme is involved in a vital process and in a high concentration.
Summarize Penicillin and its effects
Forms a covalent bond with the active site of transpeptidase. Transpeptidase would otherwise create the cross links needed to keep a bacterial cell wall strong enough to resist busting when in hypotonic solution. In the presence of penicillin, bacteria suffer from cell lysis.
Outline the steps of interactions between substrates and enzymes
(1) Substrate approaches the active site via diffusion, then electrostatic attraction takes place. (2) As the substrate binds, it causes a change in the active site that destabilizes bonds in the substrate and favors bond formation of the product(s). (3) If a second substrate is involved, it will bind in a different part of the active site. (4) Product bonds form, products are emptied out of the active site due to their different properties.
Substrate-active site collision
They encounter each other via the random motion of diffusion
Outline the requirement for effective colllisions
Requires a precise orientation, which enzymes can help achieve if the substrate is in very close proximity.
Outline reactions in cell cytoplasm
Relatively small substrates compared to enzymes, so while both are free-floating, substrate measurement is critical.
Outline the process if a enzyme is immobilized
Substrates must move towards them, usually down a concentration gradient.
Outline intercellular enzymes
Comes from ribosomes. Eg. Glycolysis reactions occurring in the cytoplasm
Outline extracellular enzymes
Made by ribosomes embedded in the endoplasmic reticulum, which forms vesicles that secrete these exoenzymes. Eg. digestive enzymes are secreted into the intestines of animals to break down macromolecules.
Define Metabolism
The complex network of interdependent chemical reactions within an organisms
Outline the steps for metabolic reactions to form pathways
(1) Arranges in chains or cycles, where each product is a substrate for the next step. (2) Catalyzed by enzymes specific to each step, which requires organisms to make many different enzymes. (3) Controlled by regulating the number of enzymes or inhibiting their function.
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