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AP Biology > Chapter 6: An Introduction to Metabolism > Flashcards

Chapter 6: An Introduction to Metabolism Flashcards

1
Q

What is metabolism?

A

the sum of all chemical reactions in an organism

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2
Q

What is a metabolic pathway?

A

A process that begins with a starting molecule which is then altered in a series of defined steps, resulting in a certain product

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3
Q

What two processes are included in the overall metabolic process?

A

Catabolic and Anabolic pathways?

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4
Q

What is catabolic?

A

A pathway that releases NRG together when complex molecules are broken down

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5
Q

What is an anabolic pathway?

A

A pathway which requires NRG to put together complex molecules

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6
Q

What is bioenergetics?

A

the study of how energy flows through living systems and is essential to look at in order to understand metabolic processes of the cell

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7
Q

What is energy?

A

the capacity to cause change.

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8
Q

What is chemical energy?

A

the potential energy available for release in a chemical reaction

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9
Q

What is thermodynamics?

A

The study of the energy transformations that occur in a collection of matter

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10
Q

What happens in an open system?

A

Energy and matter can be transferred between the system and its enviroment. Organisms are open systems, they absorb energy and release heat.

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11
Q

What is the first law of thermodynamics?

A

Energy can be transferred and transformed, but it can not be created or destroyed.

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12
Q

What is the second law of thermodynamics?

A

Every energy transfer or transformation increases the entropy of the universe

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13
Q

What does the quantity of entropy measure?

A

disorder or randomness

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14
Q

What is unusable heat associated with?

A

increased entropy

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15
Q

What is a spontaneous reaction?

A

a reaction that can proceed without requiring the input of energy, it is energetically favorable, and increases entropy of the universe

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16
Q

T/F: A spontaneous reaction requires the input of energy?

A

True, but just the activation energy

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17
Q

What is a nonspontaneous reaction?

A

a reaction that will happen only if energy is supplied and leads to a decrease in entropy

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18
Q

What is free energy?

A

the proportion of a system’s NRG that can perform work when temperature and pressure are uniform throughout the system

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19
Q

What is an exergonic reaction?

A

a spontaneous reaction that proceeds with the release of free energy

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20
Q

What is the common misconseption with the statement that breaking bonds releases energy?

A

breaking bonds DOES NOT release energy, it REQUIRES energy. The release of energy in a chemical reaction occurs when bonds are broken and new bonds are formed and the products have less free energy than the reactants had.

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21
Q

What is an endergonic reaction?

A

other, nonspontaneous reactions that can be made to proceed only with the addition of free energy

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22
Q

What is metabolic equilibrium equal to?

A

death

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23
Q

How is disequilibrium maintained?

A

because the products of one reaction do not build up, but are used in another reaction or expelled as waste from the cell

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24
Q

What are the three main types of work?

A

chemical work, transport work, and mechanical work

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25
Q

What powers cellular work, and how?

A

ATP, by coupling exergonic reactions to endergonic reactions

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26
Q

WHat is chemical work?

A

the pushing of endergonic reaction

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27
Q

What is transport work?

A

the pumping of substances across membranes

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28
Q

What is mechanical work?

A

contracting of muscles and movement

29
Q

What is energy coupling?

A

the use of an exergonic reaction to power an endergonic reaction

30
Q

How can the bonds of ATP be broken?

A

by hydrolysis, which is considered an exergonic reaction

31
Q

What is the change in G of hydrolysis in cellular respiration?

A

-7.3

32
Q

Explain the function of the phostphate groups in ATP/

A

The three phosphate groups in ATP have a negative charge which contributes to the instability of the molecule and high free energy. THis portion of the molecule could be compared to a compressed spring.

33
Q

How do cells use the energy released from hydrolysis.

A

With the help of enzymes, cells are able to use energy released by ATP hydrolysis to drive a chemical reaction that is endergonic

34
Q

How can two reactions be coupled to create a exergonic reaction

A

If the delta G of the endergonic reaction is less than the amount of energy released by ATP hydrolysis, the two reactions can be coupled so that the overall reaction is exergonic

35
Q

What is the key to coupling exergonic and endergonic reactions?

A

The formation of a phosphorylated intermediate which is more reacive

36
Q

Where does the energy required for the regeneration of ATP come from?

A

exergonic (catabolic) reactions in the cell

37
Q

What is ATP converted into?

A

ADP and phosphate, which are more stable

38
Q

What does the loss of a phosphate do?

A

makes ADP have less NRG and be more stable

39
Q

Is the regeneration of ATP an exergonic or endergonic reaction?

A

endergonic

40
Q

Is the breaking of ATP an exergonic or endergonic reaction?

A

exergonic

41
Q

What is the rate of reaction?

A

the speed at which a reaction moves toward equilibrium, which is controlled by concentration gradients and enzymes

42
Q

What is an enzyme?

A

a macromolecule that acts as a catalyst to speed up a reaction without being consumed by the reaction

43
Q

What is the activation energy?

A

the initial investment of energy necessary to break bonds in the reactants and get the reaction started

44
Q

What is activation energy often in the form of?

A

heat that the reactant molecules absorb from the surroundings

45
Q

What does the activation energy, when inputted, do?

A

allows the reactants to reach their transition state at which point they are unstable and primed to break and reform bonds

46
Q

Why is adding heat, even though it speeds up a reaction, not appropriate for most biological systems?

A

high temperatures denatures proteins and kills cells and it would speed up all reactions, not just the one needed

47
Q

How does an enzyme catalyze a reaciton?

A

by lowering the activation energy needed enabling the reactant molecules to absorb enough energy to reach the transition state at moderate temperatures

48
Q

What is a substrate?

A

the reactant that an enzyme acts on

49
Q

What is the enzyme-substrate complex?

A

the enzyme binds to its substrate

50
Q

What part of an ennzyme actually binds with the substrate?

A

the active site

51
Q

What is the specificity of an enzyme attributed to?

A

the compatible fit between the active site and the substrate

52
Q

Explain the concept of induced fit.

A

The active site does not fit rigidly like a lock and key. As the substrate enters the active site interaction of the R groups of the amino acids causes the enzyme to change its shape slightly so that the active site fits even more snuggly around the substrate

53
Q

T/F: Enzymes are anabolic

A

False - (kind of) Enzymes can be catabolic or anabolic depending on whether they break down or combine molecules respectively

54
Q

What are the four enzyme mechanisms that lower activation energy?

A

1.) The active site provides a template for the substrates to come together.
2.) The enzyme stresses and bends the chemical bonds that must be broken thus lowering activation energy.
3.) The active site provides a microenviroment that is conductive for the reaction to proceed.
4.) Direct participation of the active site in the chemcial reaction

55
Q

What are the factors that affect the rate of reaction?

A

Substrate concentration, enzyme concentration, temperature, and pH

56
Q

Explain how substrate concentration affects the rate of reaction?

A

Increasing substrate concentraition will increase the rate of reaction in direct proportion until all enzume molecules have their active site engaged. At that point the enzyme is said to be saturated. The only way then to increase the rate of reaction is to increase the amount of enzyme.

57
Q

Explain how enzyme concentration affects the rate of reaction?

A

Increasing the enzume concentration will increase the rate of reacition as long as there is enough substrate for enzymes to work on.

58
Q

Explain how temperature affects rate of reaction.

A

Enzyme rate will increase until a point where the enzyme denatures

59
Q

Explain how pH affects rate of reaction.

A

Most work best at a pH of 7 but will vary depending on the enzyme

60
Q

What are coenzymes?

A

organic molecules that aid enzymes in lowering activation energy. Many of these are vitamins that we get in our diet.

61
Q

What are cofactors?

A

inorganic enzyme helpers, which are usually minerals.

62
Q

What determines if an inhibitor is reversible or irreversible?

A

if an inhibitor attaches to the enzyme by a covalent bond it is usually irreversible but if it attaches by weak interactions the inhibition is reversible

63
Q

What do competitive inhibitors do?

A

reduce the productivitiy of enzymes by blocking substrates from entering the active site. This type of inhibition can be reversed by increasing the concentration of the original substrate.

64
Q

What do noncompetitive or allosteric inhibitors do?

A

do not directly compete with the substrate for active sites. Instead they bind to another part of the enzyme changing the enzyme’s shape so that it is less effective. The site of attachment is called the allosteric site.

65
Q

What is allosteric regulation?

A

the term used to describe any case in which a protein’s function at one site is affected by the binding of a regulatory molecule to a seperate site.

66
Q

What can allosteric regulation result in?

A

either activation or inhibition

67
Q

What happens in cooperativity?

A

the binding of one substrate molecule can stimulate the binding or activity at other active sites.

68
Q

What happens in feedback inhibition?

A

the end product of a metabolic pathway allosterically inhibits the enzyme from a previous step in the pathway. Most commonly used to maintain homeostasis by preventing overproduction of products in a cell (negative feedback).

69
Q
A

AP Biology (12 decks)

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