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Bio II > Lecture 2: Energy in Life > Flashcards

Lecture 2: Energy in Life Flashcards

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Biology 101 flashcards
1
Q

The terms Phototroph and Chemotroph reflects different ways of obtaining __________ .

A

Energy

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2
Q

5 forms of energy in life

A
  1. Radiant Energy
  2. Chemical Energy
  3. Thermal Energy
  4. Mechanical Energy
  5. Electrical Energy
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3
Q

Energy is not “circulated”, it_______.

A

Flows (no matter created or lost but its transformed, creating a cycle)

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4
Q

What is the first law of thermodynamics?

A

Energy can be transformed or transferred but cannot be created or destroyed

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5
Q

What is the second law of thermodynamics?

A

Energy transfer or transformation is not 100% efficient as some energy is “lost” as the entropy of the universe increases.

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6
Q

What is energy lost as, as organisms transform/transfer energy?

A

heat

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7
Q

Why do organisms require energy?

A

Organisms use energy to power biological work.

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8
Q

What kinds of work do organisms carry out?

A

A. Synthesizing molecules to build complex structures and to reproduce.
B. Movement of the body, cells, and substances within cells.
C. Transport of chemicals across the cell membrane. (cellular level)

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9
Q

What type of work is this?

A

Synthesizing work

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10
Q

What type of work is this?

A

Movement work

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11
Q

What type of work is this?

A

Transport work (neuron)

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12
Q

What happens when a nonspontaneous process is coupled with a spontaneous process?

A

The overall process is made spontaneous.

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13
Q

What does most energy coupling in cells rely on?

A

ATP hydrolysis

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14
Q

Name these three spontaneous reactions

A

(a) Gravitational Motion
(b) Diffusion
(c) Chemical Reaction

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15
Q

What are the two factors that determine the spontaneity of a process?

A

1.The change in potential energy.
2.The change in the degree of order.

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16
Q

If the end state of a process has lower potential energy than the starting state, …

A

the process tends to be spontaneous

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17
Q

If the end state of a process is less ordered than the starting state, …

A

the process tends to be spontaneous

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18
Q

What is the Gibbs Free-Energy change Formula?

A
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19
Q

Explain the Gibbs Free-Energy Formula

A

*Free-energy is used to determine if a process is spontaneous or not

*To determine this, it is necessary to assess the combined contributions of change of potential energy and changes in disorder.

*In the formula, enthalpy (ΔH) is “the change in potential energy” and entropy (ΔS) is the “changes in disorder”.

*The TΔS term simply means that entropy (S) becomes more important in determining free-energy change as the temperature of the molecules increase.

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20
Q

What does exergonic means?

A

ΔG < 0: Process is spontaneous

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21
Q

What does endergonic means?

A

ΔG > 0: Process is non-spontaneous

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22
Q

What does it mean when ΔG = 0?

A

Process is at equilibrium.

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23
Q

What does ΔG represent in an exergonic process?

A

represents the energy available to carry out work when a process occurs.

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24
Q

What does ΔG represent in an endergonic process?

A

represents the energy required to carry out a process.

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25
Q

What are the characteristics of a Spontaneous process?

A

*Can be used to carry out work.

*Proceed towards equilibrium (ΔG=0)

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26
Q

What type of process is that?

A

Spontaneous Process (isolated hydroelectric system)

27
Q

What happens in this process if it is a closed system?

A

A spontaneous process reaches equilibrium in a close system and work stops.

28
Q

What type of process is that?

A

*Dynamic Equilibrium

*Forward process occurs at the same rate as the reverse process.

29
Q

What is Chatelier’s Principle on chemical equilibrium?

A

Chemical equilibrium can be disturbed (or prevented) by changing parameters.

30
Q

What happens in this process if it is an opened system?

A

A spontaneous process does not reach equilibrium in an open system and work continues. (opened hydroelectric system)

31
Q

Are organisms open or close systems? Explain.

A

*Open

*Most chemical reactions in cells do not reach equilibrium (ΔG = 0).

*Reactants and products are maintained at steady-state (stable) concentrations not equilibrium concentrations, so reactions remain exergonic (ΔG < 0).

32
Q

Do reactions such as: ATP -> ADP +Pi reach equilibrium?

A

No, ATP keeps carrying out work in the steady state of concentrations in the organism.

33
Q

Is the “steady-state” in an organism the same as “equilibrium”?

A

No, it’s just steady concentrations for the body to keep carrying exergonic reactions.

34
Q

What is ATP?

A

*Adenosine triphosphate (ATP) is the energy currency used for most work in the cell via energy coupling.

*ATP has high chemical energy and hydrolysis is highly exergonic.

35
Q

What is this process?

A

Energy production as ATP is hydrolyzed

36
Q

What does ATP consist of (structure)?

A
37
Q

Which of the four classes of biomolecules is ATP associated with?

A

Nucleic Acids

38
Q

ATP is a multifunctional molecule in cells. Can you provide an example of a use other than energy currency?

A

Cellular signalling (cell communication): hydrolysis of ATP (phosphorylation/dephosphorylation) activates/deactivates target proteins.

39
Q

What is the result of the hydrolysis of the bond between the two outermost phosphate groups in ATP?

A

It results in the formation of ADP (adenosine diphosphate) and Pi (inorganic phosphate, H2PO4−) in a highly exergonic reaction.

40
Q

How is the hydrolysis of ATP characterized in terms of energy, and what is the significance of the term “exergonic”?

A

*The hydrolysis of ATP is characterized by the release of energy, and it is described as an exergonic reaction.

*Exergonic means that the reaction releases more energy than it consumes.

41
Q

Why is the hydrolysis of ATP considered exergonic? (Think of delta G and what determine it)

A

A. The hydrolysis of ATP is considered exergonic because there is a large drop in potential energy when the more stable ADP and Pi are formed from ATP.
B. The entropy of the product molecules is much higher than that of the reactants.

42
Q

Why might ATP have high potential energy making it less stable? Hint: are there repulsive charges in the molecule?

A

The three negatively charged phosphate groups contain a lot of potential energy and the electrostatic repulsion makes the molecule less stable.

43
Q

What would be the result of ATP hydrolysis in a test tube, and how is the energy released during this process manifested?

A

ATP hydrolysis in a test tube would result in the loss of energy, which is released as heat.

44
Q

How do cells utilize the energy released from ATP hydrolysis?

A

Cells use the energy released from ATP hydrolysis to make things happen.

45
Q

How does ATP hydrolysis drive endergonic processes in cells, and what are some examples of these processes?

A

ATP hydrolysis provides energy to alter molecules and drive endergonic reactions in cells. Examples include macromolecular synthesis, active transport, and mechanical work like muscle contraction.

*(important point here is that “ATP hydrolysis is used to alter a target molecule and drive an endergonic process.”)

46
Q

What are the three types of work associated with ATP hydrolysis?

A

A. Synthesis work
B. Transport work
C. Mechanical work

47
Q

Explain how ATP can carry Synthetic Work.

A
  • Phosphorylation of a reactant increases its potential energy and produces an “activated” reactant.
  • Converts an endergonic reaction into an exergonic reaction.
  • ATP powers synthetic work in this way.
48
Q

Explain the process of “Activating” a Reactant.

A
49
Q

Explain how ATP can carry transport work.

A
  • Phosphorylation of a protein causes the protein to change its shape.
  • The change in shape will change the activity of the protein.
  • Protein phosphorylation is ATP used for transport work.
  • Protein phosphorylation is also used to regulate the activity of other proteins.
50
Q

What does it mean to Phosphorylate?

A

Chemical reaction to add a phosphate group to a component.

51
Q

Explain how ATP can carry out Mechanical Work.

A

*Non-covalent interaction of ATP with a motor protein and its hydrolysis causes the protein to change its shape and change its interaction with the cytoskeleton.

*Causes movement at a molecular level.

*Basis of movement at a cell level and organismal level.

52
Q

Examples of ATP carrying mechanical work?

A

*muscle contraction, separation of sister chromatids, transport of vesicles along the cytoskeleton, etc

53
Q

How can sources of energy obtained through photosynthesis or ingestion be utilized and stored in organisms?

A

it can be transformed into usable energy and stored in organisms.

54
Q

What processes are involved in transforming the energy from glucose into ATP?

A

Cellular respiration & fermentation

55
Q

How is ATP utilized within cells to facilitate various activities?

A

ATP can be used to power cellular work.

56
Q

Give examples of energy transformation and what type of energy is being transformed?

A

*Cellular respiration, fermentation: chemical energy to chemical energy

*Photosynthesis: radiant energy to chemical energy

57
Q

Why do organic molecules like carbohydrates and fats make good fuels in energy metabolism?

A

because they have high chemical energy

58
Q

What is chemical energy, and how is it determined in a molecule?

A

the potential for a molecule to be transformed in a chemical reaction, and it is determined by the bonds in that molecule.

59
Q

How is high chemical energy associated with the breakdown of a molecule?

A

High chemical energy is associated with a large decrease in free energy when that molecule is broken down.

60
Q

What factor is associated with the amount of chemical energy in an organic molecule used as a fuel?

A

The more C-H bonds in an organic molecule (used as a fuel), the more chemical energy in that molecule, making it a better fuel.

61
Q

What term is used to describe the electrons in a nonpolar bond, and why?

A

“high energy” or “hilltop” electrons because they are equally shared between the two atoms.

62
Q

How are the electrons in a polar bond characterized, and what term is used to describe them?

A

“low energy” or “bottom” electrons because they are tightly associated with the electronegative atom.

63
Q

Which molecule is the best fuel? Why?

A

fatty acid, because it has the highest chemical energy (per gram)

Bio II (21 decks)

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