Bio U3 AOS2

• For random errors, repeat the experiment to increase the precision of the results.
• Enzymes are a type of globular protein that catalyse (speed up) biological reactions by lowering the activation energy of the reaction.
• Enzymes are not used up in a reaction and can facilitate several reactions or be reused.
• Globular proteins are water soluble and shaped like a sphere or a globe upon folding.
• Co-enzymes cycle from unloaded to loaded to unloaded based on ATP -> ADP -> ATP cycle and help enzymes to function.
• Co-enzymes carry electrons, or hydrogen ions (or protons) through a biochemical reaction and are re-used.
• Enzymes have a 3D shape (tertiary or quaternary structure) and are specific for one substrate.
• Substrates bind to the active site of an enzyme, allowing the formation of a new product.
• The enzyme holds onto the substrate in the correct orientation.
• The process of enzyme function involves the enzyme having an active site where the reaction will take place.
• If the enzyme doesn't have the correct shape for the active site yet, a co-enzyme may fill up that region and form an optimal enzyme.
• Substrate moves to the enzyme, binds to the specific active site of a specific enzyme, but may not perfectly fit due to small gaps.
• The active site of the enzyme will change shape to allow the substrate to bind fully to the active site, a process known as the induced fit model.
• In the case of a perfect fit between the enzyme and substrate, this model is called the lock and key model.
• Once the substrate is bound, the activation energy is lowered and the reaction can take place.
• The substrate will be converted into its product by either combining two substrates to form one product, or breaking down a substrate into two products.
• The newly formed product detaches from the enzyme's active site, and a new substrate may bind to the empty enzyme.
• Competitive inhibition occurs when the inhibitor binds to the active site and competes with the substrate for binding to the enzyme, blocking the binding of the substrate to the enzyme (preventing stage 1).
• Competitive inhibition decreases the rate of reaction (slower to convert substrate into product), although with enough time, the competitive inhibitor will reach the reaction rate of a normal enzyme.
• Non competitive inhibition occurs when the inhibitor does not bind to the active site, but causes a change in the 3D shape of the enzyme, blocking the enzyme from functioning (preventing stage 2).
• Non competitive inhibition decreases the amount of product that can be made, preventing the maximum reaction rate even with high substrate levels.
• Enzyme denaturation: When an enzyme is outside its optimal conditions it can become denatured, which means that it will lose its 3D shape and consequently stop functioning.
• This happens in non ideal pH levels for example, where the different level of pH to what the enzyme is used to will begin to denature the enzyme itself.
• Enzymes may denature when they are above its optimal temperature.
• Most enzymes are not stand alone, as they tend to be a part of a series of biochemical reactions (metabolic reactions).
• A series of biochemical reactions controlled by enzymes.
• If one enzyme denatures, then it will impact the product formation and may inhibit the whole biochemical pathway.
• When answering a question about enzymes, always refer to the specific enzyme, for example, RuBisCo is involved in the calvin cycle, rather than writing the enzyme is involved in the calvin cycle.
• An enzyme cannot denature in low temperatures (only high temperatures).
• Enzymes can be regulated by other molecules, and enzyme inhibitors result in a reduction in their rate of reaction, or it may stop the reaction all together.
• Inhibitors act by preventing the substrate from binding to the active site.
• Inhibition can be reversible (temporary loss of enzyme activity) or irreversible (permanent loss of enzyme activity).
• Most enzyme inhibitors are released as a defence mechanism (against pathogens) or are drugs (used in medicine).
• For systematic errors, change either the method or the instrument used to measure the dependent variable to increase accuracy.
• Photosynthesis


  Process in plants using light energy to produce glucose and ATP.
• Chloroplast


  Organelle in plant cells where photosynthesis occurs, containing grana and stroma.
• Grana


  Stacks of thylakoid discs in chloroplasts, containing chlorophyll for light-dependent reactions.
• Thylakoid


  Disc-shaped membrane structure within chloroplasts, site of light-dependent reactions.
• Chlorophyll


  Green pigment in thylakoid membranes that captures light energy for photosynthesis.
• Stroma


  Fluid-filled space in chloroplasts where light-independent reactions occur, also known as the Calvin cycle.