Biology: Unit 4

How does feedback inhibition work?

A cellular control mechanism in which an enzyme that catalyzes the production of a particular substance in the cell is inhibited when that substance has accumulated to a certain level, thereby balancing the amount provided with the amount needed.

Define active site

A small port on an enzyme where the substrate fits in. This is where the chemical reaction occurs.

Define reactants

A substance that takes part in and undergoes a change during a reaction

Define Eactivation

The minimum amount of energy required to convert a normal stable molecule into a reactive molecule.

Differentiate between Catabolism and Anabolism.

Anabolism is when enzymes take two substrates and make it into one product. This will require energy but is important to life because it is how the body makes complex molecules. It takes two basic substrates to make a complex product. Catabolism is when an enzyme breaks down a substrate into two products. This outcome comes along with energy, which explains how it can power our whole body the way it does. If catabolism produces more energy than anabolism needs then there will be a build up of fat to store energy.

Describe the role of cofactors in enzyme action, distinguishing between organic and inorganic molecules as co-factors.

Cofactors aid in catalysing reactions, some enzymes require them to catalyse substrates. There are two groups organic and inorganic. Organic cofactors generally are found in vitamins, inorganic cofactors are also essential to some enzymes.

Differentiate between competitive and non-competitive inhibition.

Competitive inhibitors have the same structure as the substrate, they fit right into the enzyme and stay there. Not allowing any substrates to be catalysed by the enzyme, thus rendering the enzyme useless. Non-competitive inhibitors attach themselves to parts other than the active site of the enzyme. This means disrupts the enzyme therefore greatly lowering its ability to catalyse substrates.

Define entropy

Disturbance or messiness

Rate of reaction / enzyme activity vs Enzyme Concentration

Drastic increase when enzyme concentration is increased. The rate is much greater.

Rate of reaction / enzyme activity vs Substrate concentration

The more concentrated the substrate the faster the the enzyme will be catalysing reactions because right when it is done it can move to the next one.

Explain how enzymes speed up reactions.

Enzymes do this by lowering the activation energy required to start the reaction.

Compare exergonic and endergonic reactions in terms of free energy.

Exergonic - A process with a net release of energy Endergonic - A process that takes free energy from its surroundings

Laws of Thermodynamics.

First law of thermodynamics - Energy can neither be created nor destroyed. It can only change forms. In any process, the total energy of the universe remains the same. Second law of thermodynamics - The entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium. Energy can change forms but it will also remain at the same value governs energy transformations.

What does it mean to say that enzymes are denatured.

It means that their full shape isn't complete because it isn't bonded with a substrate so it is missing part of it. Also if an enzyme loses its shape it will become denatured and rendered useless.

Closed VS Open Systems

Open System: A system in which energy and matter can pass through freely. Closed System: A system in which only energy can pass freely.

Explain the role of Enzymes in the metabolic pathway.

Our body weight is controlled by Catabolism minus Anabolism. Enzymes are what catalyse both of these, they are what allows our body to move by Catabolism, and they are what allows our body to burn energy through making complex molecule by Anabolism. Without enzymes we wouldn't be able to live because there wouldn't be energy to allow us to move, thus making it essential in the metabolic pathway.

Differentiate between Potential and Kinetic Energy

Potential energy is energy ready to go. For example ATP is potential energy and so is a gasoline. Kinetic energy is energy in motion like a moving car.

How does ATP drive cellular work through chemical energy?

Provide chemical energy to allow Mechanical Function for cells Active transport of ions and molecules Synthesis and breakdown of large molecules

The factors that affect an enzymes function and why this occurs.

Temperature, Acidity and Basicity, and Concentration. The temperature affects how fast the molecules move and puts strain on H-bonds. Acidity and Basicity interfere with the ionic and covalent bonds. Concentration will change how often they collide, a high concentration of either will increase the collision rate.

Describe what the activation energy is for a chemical reaction.

The amount of energy needed for the chemical reaction to take place.

Rate of reaction / enzyme activity vs temperature

The closer the temperature to 37 degrees, the greater the enzyme activity. Enzyme denaturation can occur at greater temperatures.

Explain energy coupling and how it is used to drive cellular work.

The free energy released from the exergonic process is absorbed by the endergonic process. Phosphate group transfer is the basis to most cellular work, since energy coupling is essentially phosphorylation it drives cellular work.

Rate of reaction / enzyme activity vs surface area

The greater the surface area the easier it is for the enzymes to catalyse the reactions.

Define substrate

The material or substance on which an enzyme acts.

Define products

The substance produced after the chemical reaction

Rate of reaction / enzyme activity vs pH

This depends on the specific enzyme and what it is catalysing however a ph of 7 or neutral tends to be beneficial.

Explain the induced-fit model of enzyme function.

This model shows the enzyme in a shape before the substrate has entered its active site. Once a substrate enters the active site the enzyme changes shape meaning that the enzyme's shape changes. This still means that generally only one substrate fits for one enzyme.

Why is chemical energy so important to living things?

To stay alive, cells must be able to release the energy stored in bonds.

Define enzyme-substrate complex

When the substrate bonds with the enzyme active site, and an enzyme-substrate complex is formed.

Explain phosphorylation by ATP.

When water is added to ATP, the product is ADP + Energy + Phosphate. The energy is used for cellular processes. To turn the ADP back into ATP, you take ADP and a Phosphate. Then take energy from Respiration or photosynthesis to create ATP and H2O