Enzymes 1.8 U1 Flashcards
What are ex of physical and chemical changes and what is equilibrium/homeostasis?
2H2+O2 —> 2H2O H2O(l) —> H2O(g)
Chemical Physical
Equilibrium is when a reaction goes both ways( <—->)
Chemical vs Physical Reaction?
Chemical reactions involve the breaking and/or forming of bonds. This is DIFFERENT from a physical change, like something changing state or being cut into pieces. One common misconception is that something melting/boiling/freezing/etc is a chemical reaction. It is NOT. In order for something to be a chemical change/reaction, the chemical itself must be changing in some way. So for example, if you have an ice cube that melts, it is still water. If you boil water, it is STILL H2O, it just happens to now be a gas versus a liquid. So, those would both be physical changes. If you were to take water and break it apart into hydrogen and oxygen gas, though, that would then be a chemical change, because it is no longer H2O.
What is a coefficient in terms of a reaction?
When looking at a chemical reaction, the number in front of a substance is called the coefficient, and it tells you how many of that particular substance is needed for the reaction to occur. In this example with water, you need 2 molecules of H2 and only 1 molecule of O2, in order to form 2 molecules of H2O.
What are the letters to know the states of matter?
Some chemical reactions will have a letter in parentheses after each substance. The letter tells you what state of matter that substance is in. For example, if this reaction said O2 (g), that would tell you that it is oxygen gas specifically. “g” for gas, “l” for liquid, “s” for solid, “aq” for aqueous (dissolved)
Exothermic Reaction?
An exothermic reaction releases energy from the system in the form of heat.
. Exothermic reactions can happen on their own (“spontaneously”)
- The reaction is colder than surroundings
Endothermic Reaction?
An endothermic reaction absorbs energy from its surrounding in the form of heat.
endothermic reaction cannot happen unless there is an input of energy.
- The reaction is hotter than surroundings
Know the potential energy diagram?(how do you determine if its endo or exothermic based off the graph?)
We call these types of graphs “potential energy diagrams”. You can determine if a reaction is endothermic or exothermic by looking at the energy level of the products versus the reactants.
Explain the example reaction of the formation of water?
2H2(g)+O2 —> 2H2O(g) + Energy
this reaction releases energy, and happens spontaneously
in order to reverse this reaction, you have to input energy, it doesn’t occur on its own!
EX. You have to run an electric current through water to decompose it into hydrogen and oxygen gas!
What is activation energy(Ea)? and their relation to exo/endothermic reactions?
Energy needed to start a reaction
In the case of an exothermic reaction, the reactants are at a higher energy level as compared to the products, as shown below in the energy diagrams. In other words, the products are more stable than the reactants. Overall ΔH for the reaction is negative, i.e., energy is released in the form of heat.
In the case of an endothermic reaction, the reactants are at a lower energy level compared to the products—as shown in the energy diagram below. In other words, the products are less stable than the reactants. Since we are forcing the reaction in the forward direction towards more unstable entities, overall ΔH for the reaction is positive, i.e., energy is absorbed from the surroundings.
What is a catalyst?
speeds up chemical reaction by lowering activation energy
Reusable!
What is an enzyme?
a biological catalyst (protein!)
Reusable!
what does the enzyme actually do to the substrate to make the activation energy lower?
The answer depends on the enzyme. Some enzymes speed up chemical reactions by bringing two substrates together in the right orientation. Others create an environment inside the active site that’s favorable to the reaction (for instance, one that’s slightly acidic or non-polar). The enzyme-substrate complex can also lower activation energy by bending substrate molecules in a way that facilitates bond-breaking, helping to reach the transition state.
Factors that may affect the active site and enzyme function include:
Temperature. A higher temperature generally makes for higher rates of reaction, enzyme-catalyzed or otherwise. However, either increasing or decreasing the temperature outside of a tolerable range can affect chemical bonds in the active site, making them less well-suited to bind substrates. Very high temperatures (for animal enzymes, above 40∘C or 104∘F) may cause an enzyme to denature, losing its shape and activity.
pH. pH can also affect enzyme function. Active site amino acid residues often have acidic or basic properties that are important for catalysis. Changes in pH can affect these residues and make it hard for substrates to bind. Enzymes work best within a certain pH range, and, as with temperature, extreme pH values (acidic or basic) can make enzymes denature.
What is Denature?
Breaking of enzyme down
What are substrates?
Reactants
