Bio 190A > Chapter 6 - Utilizing Energy > Flashcards

Chapter 6 - Utilizing Energy Flashcards

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1
Q

What is energy?

A

The ability to promote change or do work (examples: light, heat, mechanical, chemical potential, electrical/ion gradient)

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2
Q

What is potential energy?

A

Stored energy, due to structure or location (think of a bow an arrow)

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3
Q

What is chemical potential energy?

A

The energy in bonds between atoms (biologically important form of potential energy)

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4
Q

What is kinetic energy?

A

Energy than an object had because of its motion, associated with movement (think of a baseball bat hitting a ball)

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5
Q

What is the first law of thermodynamics?

A

Energy cannot be created or destroyed, but it can be transformed from one type to another

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6
Q

What is the second law of thermodynamics?

A

A transfer of energy from one form to another increases the entropy (degree of disorder)

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7
Q

What is free energy?

A

Useable energy, the amount of energy available to do work

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8
Q

How do the laws of thermodynamics relate to living things?

A

They are fundamental to the metabolic process that sustains life

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9
Q

How does the change in free energy determine the direction of a chemical reaction?

A

A change in free energy will determine if a reaction occurs spontaneously

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10
Q

What is a spontaneous reaction?

A

A reaction that occurs in a particular direction without being driven by an input of energy

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11
Q

What is an exergonic reaction?

A

The products have less free energy than the reactants (free energy is released during the reaction)

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12
Q

What is an endergonic reaction?

A

The products have more free energy than the reactants (free energy must be added during the reaction)

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13
Q

How do cells use the energy released by ATP hydrolysis to drive endergonic reactions?

A

Endergonic reactions can be couples to an exergonic reaction; ATP hydrolysis is an exergonic reaction that often couples up with other reactions

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14
Q

What will a reaction be if the coupled endergonic and exergonic reaction if the overall free energy charge for both is negative?

A

The reaction will be spontaneous

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15
Q

What is a catalyst?

A

An agent that speeds up the rate of chemical reaction without being consumed during a reaction

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16
Q

How do enzymes increase the rates of chemical reactions by lowering activation energy?

A

They act as biological catalyst that lower the activation barrier which makes their transition state come faster

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17
Q

Once reactants achieve a transition state, original bonds have reached their ___

A

Limit and can create products

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18
Q

How do enzymes bind their substrates with high specificity and undergo an included fit?

A

The enzyme-substrate complex is formed when an enzyme and substrates bind (enzyme undergoes conformational changes upon substrate binding)

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19
Q

What is Affinity?

A

The attraction of an enzyme for a substrate

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20
Q

What is the difference between an enzyme with a strong affinity and an enzyme with a weak affinity?

A

Strong: the enzyme binds even when substrate concentration is low
Weak: the enzyme only binds at high substrate concentration

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21
Q

What is Vmax in enzyme activity?

A

The maximal rate of a reaction

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22
Q

What is KM in enzyme activity?

A

The substrate concentration where velocity is half the max

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23
Q

Cells often use ______ _______ to regulate enzyme activity

A

Reversible inhibitors

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24
Q

What is a competitive inhibitor?

A

Bond noncovalently to the active site (Km increases-more substrate is needed to achieve the same velocity)

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25
What is a noncompetitive inhibitor?
Bind to a distinct regulatory site, an allosteric site (lowers Vmax without affecting KM)
26
Some enzymes require various types of non-protein molecules or ions to function, what are the functions of three of these molecules?
**Prosthetic group**: small molecule, permanently attached to the enzyme **Cofactor**: an ion that temporarily binds to an enzyme **Coenzyme**: an organic molecule that participates in a reaction but is left unchanged
27
How do factors (like temperature and pH) influence enzyme activity?
If an enzyme is not in its optimal state, it can become denatured or be disrupted (example: a low or high pH can disrupt the ionic bonds in an enzyme)
28
What is a metabolic pathway?
Chemical reactions that are coordinated with each other
29
What is a catabolic reaction?
Break down larger molecules into smaller ones and are typically exergonic
30
What is an anabolic reaction?
Synthesize larger molecules from smaller ones and are typically endergonic
31
How are catabolic reactions used to generate building blocks to make larger molecules and to produce energy intermediates?
Since they break down larger molecules, it allows for recycling of organic building blocks
32
What is an example of an energy intermediate?
ATP or NADH
33
What is a redox reaction and the two different types?
- Involves the transfer of electrons - Oxidation and Reduction
34
What is a reduction reaction?
The gaining of electrons (RIG)
35
What is oxidation?
The removal of electrons (OIL)
36
A substance that has been oxidized has ____ energy stored in its bonds
Less
37
A substance that has been reduced has ____ energy stored in its bonds
More
38
What might cells use in order to carry out important redox reactions and what are some examples?
They use NAD+/NADH Example: reactions that breakdown food molecules like glucose or fat
39
What are the three ways metabolic pathways are regulated?
Gene regulation--increasing or decreasing gene expression for genes that encode certain enzymes Cell signaling--signals from their environment and adjust their metabolic activity Feedback inhibition (frequently used)--a product of a pathway binds a pathway enzyme at an allosteric site (decreases activity)
40
What are the 4 metabolic pathways needed to break down glucose to CO2?
1) Glycolysis 2) Pyruvate oxidation 3) Citric acid cycle 4) Oxidation phosphorylation
41
What is cellular respiration?
The process where living cells obtain energy from organic molecules
42
What is aerobic respiration?
Uses O2 during the process of oxidizing organic molecules and generates CO2
43
Where in the cell does glycolysis take place?
Cytosol
44
What are the 3 phases of glycolysis?
**1) Energy investment phase 2) Cleavage phase 3) Energy liberation phase**
45
1 molecule of glucose is transformed into _______
2 molecules of pyruvate
46
What are the net products (or what is generated) of glycolysis?
2 ATP and 2 NADH
47
True or False: Glycolysis cannot occur in the absence of oxygen.
False, Glycolysis can occur in the presence or absence of oxygen
48
Where in the cell does pyruvate oxidation occur?
The mitochondrial matrix
49
How is pyruvate oxidized?
Via pyruvate dehydrogenase
50
2 pyruvate molecules from glycolysis go in and total _______, _______, and _______ in its breakdown
2 acetyl CoA, 2 NADH, and 2 CO2
51
What is a metabolic cycle?
Some molecules enter while other leave + the process is cyclical because some molecules are regenerated
52
Where in the cell does the citric acid cycle occur?
The mitochondrial matrix
53
How does an acetyl group enter the citric acid cycle?
It converts from acetyl CoA into citrate
54
What are the net products of the citric acid cycle?
4 CO2, 6 NADH, 2 FADH2. and 2 ATP (via GTP)
55
Where in the cell does oxidative phosphorylation occur?
The inner mitochondrial membrane
56
What happens in oxidative phosphorylation?
Utilizing high energy electrons stored in NADH and FADH2 to generate a H+ gradient
57
What is the electron transport chain?
Protein complexes and small organic molecules embedded in the inner mitochondrial membrane
58
How does the electron transport chain produce a H+ electrochemical gradient?
Energy that is released during movements of electrons is used to pump H+ across the membrane
59
How does ATP synthase utilize the H+ gradient to synthesize ATP (aka Chemiosmosis)?
The flow of H+ through the ATP synthase enzyme causes conformational changes, resulting in the synthesis of ATP
60
Why is it that cells rarely achieve their maximal amount of ATP?
- NADH is used in anabolic pathways (NADH is substantial to the H+ electrochemical gradient) - H+ gradient is used for other purposes
61
What are the net products of oxidative phosphorylation?
ATP, NAD+, FAD, and water
62
How does ATP synthase spin to produce ATP?
It is a rotary machine, meaning it makes ATP as it spins
63
What are the connections between carbohydrate, protein, and fat metabolism?
All three of these macromolecules go through the same stages of cellular respiration (just at different steps)
64
An environment that lacks oxygen can be described as ________
Anaerobic
65
How do certain microorganisms make ATP using a final electron acceptor in the electron transport chain that is not oxygen?
1) **Anaerobic respiration** (uses a substrate other than O2 as the final electron acceptor) 2) **Fermentation** (produces ATP through substrate-level phosphorylation)
66
Glycolysis requires NAD+, which means under anaerobic conditions, NAD+ __________ and must be __________ to keep glycolysis running
Decreases and Regenerated (which is how cells make ATP in anaerobic conditions)
67
How do muscle cells use fermentation to synthesize ATP under anaerobic conditions?
Muscles produce lactic acid in fermentation which oxidizes NADH to NAD+, allowing glycolysis to continue
68
How do yeast cells use fermentation to synthesize ATP under anaerobic conditions?
Yeast produces ethanol in fermentation which oxidizes NADH to NAD+, allowing glycolysis to continue
Bio 190A
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