Energy, Catalysis and Biosynthesis Flashcards

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1
Q

Second Law of Thermodynamics

A

Systems will change spontaneously toward arrangements with greater entropy. Therefore, the degree of disorder (entropy) will always increase over time.

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2
Q

What is entropy?

A

The dispersal of energy

A campfire is an example of entropy. The solid wood burns and becomes ash, smoke and gases, all of which spread energy outwards more easily than the solid fuel.

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3
Q

Why is entropy always increasing?

A

Changes towards ‘disorder’ are overwhelmingly more likely than those towards ‘order’.

Example: Releasing Heat
Everything done has an amount of inefficiency so energy gets loss in some way, increasing disorder to the system.

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4
Q

If creating and growing requires ‘order’ in cells, how is the second law of thermodynamics obeyed?

A

In the process of cells growing and creating chemical functions, some energy is inevitably loss in the form of heat, increasing entropy

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5
Q

What is the first law of thermodynamics?

A

Energy cannot be created or destroyed. They can be converted from one form to another.

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6
Q

How do cells manage to create and maintain order despite ever increasing entropy?

A

Cells use a tremendous amount of energy to create and maintain order. Cells get their energy from light and food and convert them to a usable energy.

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7
Q

Free Energy

A

Energy that can be harnessed to do work or drive chemical reactions

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8
Q

What determines whether a chemical reaction can occur?

A

Delta G

Reactions that create disorder by decreasing the amount of free energy of the system because they are energetically favorable. Basically, a reaction can only occur if delta g is negative.

Energetically favorable reactions have a negative Delta G

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9
Q

What does it mean for change in free energy to be zero

A

The reaction is at equilibrium, meaning the rate of the forward reaction equals the rate of the reverse reaction. All reactions tend to proceed towards equilibrium.

Note: the concentration of reactant and product may NOT be equal.

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10
Q

How does delta g naught relate to K

A

It is directly proportional. If K is bigger, delta g naught is more negative, thus there is more free energy and more favorable.

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11
Q

What is a coupled reaction?

A

A reaction where the the free energy of a favorable transformation and a unfavorable transformation join into a new reaction to drive unfavorable reaction.

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12
Q

Coupled Reaction- Activated Carrier

A

Activated Carrier: ATP

Glucose + Fructose -> Sucrose = 23 kj/mol (unfavorable)

but when we add ATP
Glucose - ATP + Fructose -> Sucrose + P = -7.5 kj/mol (favorable)

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13
Q

What is an activated carrier? What is it use for?

A

Small organic molecules that contain one or more energy-rich covalent bonds. In a cell setting, cells used activated carrier to carry out unfavorable reaction.

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14
Q

What is a catabolic pathway?

A

Catabolic pathways are those that generate energy by breaking down larger molecules.
Energy is released when breaking down larger molecules

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15
Q

What is an anabolic pathway?

A

Anabolic pathways are those that require energy to synthesize larger molecules. Anabolic pathway used the energy generated from catabolic pathway to synthesize larger molecules.

Anabolic pathway is powered by catabolic pathway.

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16
Q

How does catabolic pathway contribute to creating order in cell?

A

The catabolic pathway break down foodstuff into smaller molecules, thereby generating
both a useful form of energy for the cell and some of the small molecules
that the cell needs as building blocks.

17
Q

How does anabolic pathway contribute to order in the cell?

A

Anabolic pathway use the generated energy (catabolic pathway produces energy when breaking down molecules ) to synthesize larger molecules.

18
Q

What is oxidation?

A

Losing an electron for another compound to gain an electron (reduction)

19
Q

What is reduction?

A

Gaining an electron

20
Q

How does cell obtain energy by the oxidation of organic molecule?

A

Cellular Respiration

Cellular respiration is an oxidative process where glucose is being oxidized. This produces energy for the cells.

21
Q

Hydrogenation

A

Hydrogenation: chemical reaction between a compound and H2.

Electron usually gets transfer with a proton. Therefore, an increase in the number of C–H bonds, in an organic molecule indicates a reduction

22
Q

Dehydrogenation

A

Chemical reaction that involves the removal of hydrogen, usually from an organic molecule.

Electron usually gets transfer with a proton. Therefore, a decrease in the number of C–H bonds, in an organic molecule indicates an oxidation.

23
Q

What are enzymes?

A

Proteins that binds onto substrate, responsible for its (nearly all) chemical transformation that occur in cell.

24
Q

What is an activation energy?

A

The minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport.

25
Q

What are substrates?

A

Molecules that enzymes bind to

26
Q

What must cells need in order to undergo chemical reactions, without the aid of raising their temperature?

A

Cells require enzyme. With heat, the activation is provided. However, because cells cannot raise their temperature, they require the aid of enzymes to reduce the activation rate for cells to undergo a chemical reaction. Even energetically favorable reaction need a boost which enzymes provide.

27
Q

What is the relationship between heat and enzymes?

A

It is true that heat raise the rate of enzyme activity. However, there is an optimal temperature for enzymes. Boiling enzyme will not cause it to be more productive; it will denature it.

28
Q

Characteristic of Enzymes

A

-Enzymes increase the rate of reactions by reducing the activation energy
- Each type of enzyme is highly specific, catalyzing only a single type of reaction.
-Does not change the equilibrium point of a reaction; enzymes accelerate the forward and reverse reaction at the same rate

29
Q

How can we measure enzyme performance?

A

By measuring how rapidly enzymes can process its substrate

30
Q

How do we measure an enzyme’s performance to a substrate?

A

Using a test tube, a fixed amount of enzymes and different concentration of substrates are added. Then, the maximum velocity of an enzyme can be measured

31
Q

What does Michaelis constant tell us?

A

Amount of substrate that allows the enzyme to reach half of its maximal speed.

It also tells us the enzyme’s affinity to its substrate.
A small KM indicates that a substrate binds very tightly to the enzyme. A big KM indicate weak binding.

32
Q

What are competitive inhibitors?

A

Molecules that block enzyme activity by competing with the substrate for the same binding site on the enzyme. They resemble the substrate enough to tie up the enzyme, but they differ enough in structure to avoid getting converted to product.

33
Q

Why don’t competitive inhibitors change the maximum velocity of enzymes?

A

Because the addition of more substrate will swamp the enzyme active site, out-competing the inhibitor, and eventually allowing the uninhibited Vmax to be achieved.

34
Q

How does Competitive inhibitors affect Km?

A

Increase KM
Because of competition with the inhibitor for the active site, more substrate must be added to achieve a half-maximal catalytic rate.

35
Q

What are Non-Competitive Inhibitors

A

Molecules that bind on an enzyme’s allosteric site, changing the shape of the enzyme so that it no longer function.

Substrate and non-competitive inhibitors can both simultaneously bind to the enzyme.

36
Q

How do non-competitive inhibitors affect KM

A

Noncompetitive inhibitors do NOT change because inhibitor binds the free enzyme and the enzyme-substrate complex with the same affinity.

37
Q

How do non-competitive inhibitors affect the maximal velocity of an enzyme?

A

Noncompetitive inhibitors lower Vmax because they inhibit the enzyme even if more substrate is added.