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BIOL 241 > Topic 2 - Thermodynamics > Flashcards

Topic 2 - Thermodynamics Flashcards

1
Q

What is a system? What are some examples? What does each biological system do?

A

Anything of interest to the biologist. This includes biochemical reactions, cells, organism, eco systems. Each biological system interacts with its surroundings.

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2
Q

What are surroundings?

A

Everything outside of a system.

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3
Q

What is an isolated system?

A

Energy and matter cannot exit or enter. An example is our universe.

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4
Q

What is a closed system?

A

Matter cannot leave or enter but energy can enter and leave. An example is a thermos.

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5
Q

What is an open system?

A

Both energy and matter can exit and enter. An example is cells, organisms.

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6
Q

What type of system are biological systems?

A

They are open systems. They acquire energy and matter from their surroundings whilst removing waste such as byproducts of metabolism and heat.

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7
Q

What is energy?

A

All biological systems needs energy. Energy is the ability to cause change.

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8
Q

What is work? What are some examples?

A

Work is the change that requires energy. Examples include DNA replication, protein synthesis, and metabolism.

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9
Q

What is potential energy?

A

It the stored energy due to the position of something.

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10
Q

What is kinetic energy?

A

It is energy due to motion and or change.

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11
Q

What is potential energy and kinetic energy in an atom?

A

The electrons further away have more potential energy. As it moves closer, its kinetic energy goes up.

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12
Q

What is the first source of cellular energy?

A

High energy electrons.

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13
Q

What determines amount of potential energy within a molecule?

A

The arrangement and positions of electrons in chemical bonds. A molecule with lots of non-polar (electrons shared equally) covalent bonds has greater potential energy than that of a polar-covalent bond as they are are farther form electrons thus Ep goes up.

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14
Q

What is the second source of cellular energy?

A

The second source of cellular energy is electrochemical gradients.

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15
Q

What is electrochemical gradients?

A

The universe hates concentration gradients. Concentration gradients have greater Ep; when there is equilibrium, there is less Ep.

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16
Q

What is the first law of thermodynamics?

A

The first law of thermodynamics is that energy cannot be created nor destroyed, it is transferred. It can change its locations and form, all energy transfers in and out from its surroundings.

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17
Q

What is Enthalpy (H)?

A

Enthalpy is the sum of Ep and Ek in a system. All molecules have Ep (arrangement of electrons in a molecule) and they all have Ek, which is the molecules moving or thermal energy.

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18
Q

What happens to the enthalpy when work occurs?

A

The system has a new and different enthalpy.

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19
Q

What happens if heat is released?

A

It is exothermic, thus products have less enthalpy than the reactants, change in H is negative.

20
Q

What happens if heat is absorbed =?

A

It is endothermic, thus reactants have less enthalpy than the products, thus change in H is positive.

21
Q

What is a spontaneous reaction? What is an example?

A

A spontaneous reaction is a reaction that can occur under the current system conditions (temp, pressure,[ ]). The oxidation of glucose is spontaneous as it is thermodynamically favourable to covert glucoses to CO2.

22
Q

Are spontaneous reactions instantaneous?

A

NO they are not, it is simply a possible reaction. If a reaction is spontaneous, it is non-spontaneous in the opposite direction.

23
Q

What is a non-spontaneous reaction?

A

A non-spontaneous reaction is a reaction that cannot occur under current conditions of the system.

24
Q

Does a spontaneous reaction determine if a rxn is endo or exo?

A

NO IT DOES NOT.

25
Q

What is entropy? (S)

A

Entropy is the measure of how dispersed energy is. All systems and surroundings have entropy.

26
Q

What happens to entropy as work occurs?

A

When work occurs, all systems and surroundings have a new entropy. (dispersion of energy in the universe changes).

27
Q

What does the + and - to entropy mean?

A

If energy is more dispersed, it is a positive change in entropy (S). If energy is less dispersed, it is a negative change in entropy (S).

28
Q

What is the second law of thermodynamics?

A

Total entropy of the universe is always increasing. Thus, every transformation and transfer MUST always increase the entropy of the universe.

29
Q

What does entropy determine?

A

Entropy determines if a reaction is spontaneous. Positive entropy means it is spontaneous, negative entropy means it is non-spontaneous.

30
Q

What is the equation of the total entropy?

A

It is Stotal = Ssystem + Ssurrounding. The S total always has to be spontaneous, this it always has to be positive.

31
Q

What is Free energy (G)?

A

All molecules have free energy. It is the measure of energy avaibule in a system to do work and carry out the change.

32
Q

What must reactants regarding free energy?

A

The reactants must have MORE free energy than the products for a change/work to occur.

33
Q

What does the + and = in free energy (G) mean?

A

A positive G means that there is free energy available, if G is negative that means there is no free energy available (products have more free energy).

34
Q

What is an exergonic reaction?

A

The change in free energy has to be negative, as there has to be a lot of energy available to carry out the change. It has to be spontaneous (S has to be positive), and free energy is released. Products have less free energy than the reactants.

35
Q

What is one of the free energy formulas?

A

G= -TStotal Stotal has to be positive as it is spontaneous and thus, entropy is positive.

36
Q

What are endergonic reactions?

A

These reactions have a positive free energy, so that means the products have more free energy. This also means there is not enough energy to carry out the change. The G is positive. Thus, this reaction is non-spontaneous and the entropy (S) is negative.

37
Q

What is the formula for the relationship between G, H and S?

A

G= H-TSsystem

38
Q

Are all biological reactions exergonic or endergonic? What happens if free energy is close to 0?

A

They are all exergonic; therefore, the free energy in reactants must be more than the products. If free energy is close to 0, this means the reaction can go in the opposite direction. At equilibrium, there is not enough free energy for the reaction to continue.

39
Q

What is standard free energy?

A

It is measured in a lab under “standard conditions”, which is much different than cellular conditions. If a tabulated G is positive, then the reverse reaction is spontaneous.

40
Q

What is metabolism?

A

It is the sum of all reactions in a cell.

41
Q

What is catabolism?

A

It is the breaking down of molecules too simpler ones. It is overall exergonic.

42
Q

What is anabolism?

A

It is making complex molecules from simpler ones.It is overall endergonic.

43
Q

How are two reactions connected?

A

They are connected if the first reaction’s product is the substrate for the second reaction.

44
Q

What are all reactions?

A

They are exergonic. They are spontaneous.

45
Q

What is ATP?

A

It is adenosine triphosphate and cells use it as short term potential energy storage molecule (high energy molecule).

46
Q

What are coupled reactions?

A

A single reaction with two things happening which are occurring at once in the the same place/

47
Q

By manipulating reactant and product concentrations….

A

Using coupled reactions, cells can change catabolic and anabolic reactions that would otherwise be endergonic to exergonic.

BIOL 241 (3 decks)

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