Metabolic Processes

Question 1

Metabolism

Answer 1

is the sum of all chemical processes occurring in a cell

Question 2

Energy

Answer 2

the ability to do work

Question 3

Kinetic E

Answer 3

is by result of a motion, it can perform work by making other objects move

Question 4

Potential E

Answer 4

is stored in a motionless object dependent on its position (ie. chemical potential in glucose, when used in rxn will produce energy as in ATP)

Question 5

The First Law of Thermodynamics

Answer 5

Energy in a closed system is constant
Energy cannot be created or destroyed, but can be converted into different forms
If something experiences a gain in energy, then another will experience a loss

Question 6

Energy Changes During a Chemical Reaction

Answer 6

Bonds get broken in reactant side, but are formed in product side
As the bonds change, the position of the electrons change

Question 7

Bond energy

Answer 7

is the minimum amount of energy needed to break particular bonds

Question 8

Activation energy

Answer 8

the minimum amount of energy needed to start the reaction

Question 9

Transition State

Answer 9

is when the reactants are breaking and the bproducts are forming

Question 10

Endothermic reaction

Answer 10

occurs when energy is absorbed giving more potential energy to the products

Question 11

exothermic reactions

Answer 11

are when energy is released and therefore there is an increase in the reactants potential energy

Question 12

Steps to calculating bond energy

Answer 12

Write balanced chemical equation
Make drawings of molecules and determine their bonds and how many
Calculate net energy change for both the reactants an dproducts sides
BEr(products)-BEa(reactants)

Question 13

The second law of thermodynamics

Answer 13

Some energy becomes unusable when energy converts from one form to another
It increases the entropy of the universe

Question 14

Entropy

Answer 14

is a measure of disorder, it occurs when energy is expended into creating order, but it creates disorder again

Question 15

To keep a low level of entropy

Answer 15

You must expend a lot of energy, ie. DNA and proteins use a lot of energy to keep their structures

Question 16

Gibbs free energy

Answer 16

Energy left that can do work
They tell us metabolism and what reactions in our bodies provide this free energy and fuel
If it comes out negative, then it means reactants have more free energy than he products and are spontaneous ..more potential energy
If the free energy is positive then the reaction is not spontaneous

Question 17

Example of Free Energy Release
Negative G

Answer 17

The oxidation of glucose is an example of a reaction that releases free energy:
C6H12O6 1 6 O2 S 6 CO2 1 6 H2O ∆G 5 22870 kJ/mol of glucose oxidized
The negative ∆G value indicates that the reaction is spontaneous. Free energy is
released during the reaction, so the products have less free energy than the reactants.

Question 18

Positive G

Answer 18

Plants combine CO2 and H2O to create sugars through the process of photo-
synthesis. This reaction is the opposite of glucose oxidation and is an example of a
chemical reaction that has a positive ∆G value:
6 CO2 1 6 H2O S C6H12O6 1 6 O2 ∆G 5 12870 kJ/mol of glucose formed
The positive ∆G value indicates that the reaction is not spontaneous—it must gain
free energy to occur.

Question 19

Exergonic reactions

Answer 19

release negative free energy

Question 20

Endergonic reactions

Answer 20

absorbs positive free energy

Question 21

Coupled reactions

Answer 21

One reaction occurs and transfers its energy to trigger the next reaction.
In catabolic pathways free energy is released negative
In anabolic reactions free energy is absorbed positive

Question 22

ATP

Answer 22

is the universal currency of energy, used in every living organism
Has three types of functions: mechanical, transportation, and chemical work.

Question 23

Mechanical work

Answer 23

Contraction of muscle fibres, beating of cilia, movement of chromosomesduring mitosis and meiosis.

Question 24

Transport Work

Answer 24

Pumping substances across the concentration gradient

Question 25

Chemical Work

Answer 25

Energy supply for non-spontaneous reactions, endergonic reactions Things like DNA and protein synthesis

Question 26

Enzymes

Answer 26

are a catalytic protein that speed up chemical reactions

Question 27

Substrates

Answer 27

are the molecules that bind to enzymes, they lower the energy barrier so that the reaction may occur at a faster rates

Question 28

Induced Fit Hypothesis

Answer 28

Prior to binding, the enzyme changes its conformation so that the active site is more accurate for the substrate to fit The binding puts stress of the substrate bonds and allows for the breaking of them Ie the sucrose

Question 29

Cofactors and Coenzymes

Answer 29

Most enzymes require a cofactor which are non-protein groups that bind to an enzyme and are essential for the activity site they are often metals ie. the iron in hemoglobin for oxygen transport Coenzymes organic factors ie. NAD+, they derive from water soluble vitamins and do the same work function as cofactors

Question 30

Enzyme and substrate concentration

Answer 30

If there is excess substrate then the rate is proportional to enzyme concentration. This is b/c the # enzymes limit the reaction. Saturation level is a result of the enzymes at a constant concentration and an increasing substrate concentration, will speed up the rate of reaction to a certain point

Question 31

Enzyme Inhibitors

Answer 31

Lower the rate at which the enzyme catalyzes the reaction, they decrease the activity of the enzymes There are three different types of inhibition competitive, noncompetitive, and feedback inhibition *when the inhibitor is released, the enzyme activity returns to normal

Question 32

Competitive inhibition

Answer 32

is when an “imposter” competes with the substrate to get into the active site of the enzyme

Question 33

Non-competitive inhibition

Answer 33

is when an inhibitor binds to the enzyme, not at the active site and when it does, it changes the shape of the active site therefore preventing the substrate from binding

Question 34

Allosteric Control of Enzyme Activity

Answer 34

Allosteric sites are an extra binding site on an enzyme that bind regulation molecules Protein molecules and their functions are affected by a molecule binding to a seperate site, this is called allosteric regulation It can inhibit or activate a site ie. the site was distorted before and was changed after inhibition Feedback inhibition is a type of regulation, the inhibitor is like a dimmer switch and can slow down or speed up the biochemical pathway it prevents wastage

Question 35

pH and Temperature

Answer 35

Enzymes reach maximal activity between specific ranges Enzymes at the peaks on the graph are at their optimal value, however past their range they may endure denaturation Denaturation is when the enzyme/protein loses their shape and structure Temp increase is usually an increase in the rate of the reaction as kinetic motion increase Peak for most enzymes between 40-50 degrees

Question 36

Applications of Enzymes

Answer 36

People who are lactose intolerant lack the digestive enzyme lactase and that enzyme is what is needed to efficiently break down lactose. If not digested properly the bacteria in the gut consumes the lactose which leads to symptoms such as nausea and cramps. Enzymes in yeast convert sugar

Question 37

Enzymes and Activation Energy

Answer 37

Enzymes do not affect where a reaction begins or ends, but reduces the activation energy needed to start them

Question 38

Enzymes as Catalysts

Answer 38

Enzymes combine with reactants to speed up the reaction and then are released unchanged They lower the potential energy of the transition state and increase the rate They do not alter physical characteristics in any way

Question 39

How do enzymes lower the activation energy?

Answer 39

They bring molecules together because the substates need to collide to reach the transition stage. When the substrates bind to the enzyme, they are within enough distance for catalysis to occur. The alter the environment charges as the active sites contain ionic roups to attract and repel parts of the substrate. This stresses the bonds. They enzyme changes shape to strain or distort the molecule which may weaken chemical bonds. This reduces the energy needed to break the bonds. Induced Fit Model