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BIOL > Ch 6-2 > Flashcards

Ch 6-2 Flashcards

1
Q

What is activation energy (EA)?

A

The energy required to start a reaction by contorting bonds into unstable states.

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2
Q

True or False: Enzymes alter the Gibbs free energy (ΔG) of a reaction.

A

False

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3
Q

What do enzymes do to the activation energy of a reaction?

A

Enzymes lower the activation energy.

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4
Q

True or False: Catalysts are consumed during the reaction they speed up.

A

False

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5
Q

What term describes the molecule that an enzyme binds to during a reaction?

A

Substrate

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6
Q

What complex is formed when an enzyme binds to its substrate?

A

Enzyme-substrate complex.

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7
Q

Which of the following is NOT a way enzymes lower activation energy?
a) Proper orientation of substrates
b) Increasing temperature
c) Stretching bonds

A

B) Increasing temp

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8
Q

What is the ‘induced fit’ model of enzyme activity?

A

It suggests that the enzyme changes shape to better fit the substrate when it binds.

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9
Q

What is a cofactor?

A

A molecule that helps enzymes bind to substrates, which can be inorganic or organic.

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10
Q

True or False: Vitamins can act as organic coenzymes.

A

True

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11
Q

What happens to the rate of an enzymatic reaction as the concentration of substrate increases?

A

The rate increases until the enzyme becomes saturated.

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12
Q

At what point does increasing substrate concentration no longer increase the reaction rate?

A

When enzyme saturation occurs.

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13
Q

True or False: Enzymes can be reused after catalyzing a reaction.

A

True

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14
Q

What two major factors affect enzyme activity?

A

Temp and pH

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15
Q

What is the optimal pH range for most enzymes in the human body?

A

pH 6-8.

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16
Q

What happens to an enzyme when it is exposed to temperatures above its optimal range?

A

The enzyme can denature, losing its function.

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17
Q

What is competitive inhibition?

A

When a molecule competes with the substrate for the enzyme’s active site.

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18
Q

True or False: Noncompetitive inhibitors bind to the active site of the enzyme.

A

False. Noncompetitive inhibitors bind to a different part of the enzyme, changing its shape.

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19
Q

What is allosteric regulation?

A

Regulation of an enzyme’s activity through the binding of molecules at a site other than the active site.

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20
Q

True or False: Allosteric regulation can both increase and decrease enzyme activity.

A

True

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21
Q

What role does ATP play in allosteric regulation of catabolic pathways?

A

ATP acts as an inhibitor.

22
Q

What is feedback inhibition?

A

The end product of a metabolic pathway inhibits an earlier enzyme in the pathway.

23
Q

True or False: Feedback inhibition helps prevent the overproduction of a product.

A

True

24
Q

What is the term for enzymes that consist of multiple subunits and show cooperativity?

A

Allosteric enzymes

25
Q

In feedback inhibition, where does the final product bind to stop further production?

A

To one of the early enzymes in the pathway.

26
Q

What is the active site of an enzyme?

A

The region where the substrate binds to the enzyme.

27
Q

What determines the specificity of an enzyme for its substrate?

A

The enzyme’s three-dimensional shape and chemical characteristics.

28
Q

True or False: The active site of an enzyme typically interacts with only a few amino acids of the substrate.

A

True

29
Q

What mechanism allows hemoglobin to increase its reactivity with each oxygen molecule it binds?

A

Cooperativity

30
Q

True or False: The active site of an enzyme is rigid and cannot change shape.

A

False. The active site can change shape through induced fit.

31
Q

Is cellular respiration an anabolic or catabolic pathway?

A

Catabolic

32
Q

True or False: Cells operate as closed systems.

A

False. Cells operate as open systems.

33
Q

What is the ΔG of a system at equilibrium?

A

Zero

34
Q

What molecule provides energy for most cellular work?

A

ATP

35
Q

True or False: ATP hydrolysis releases energy.

A

TRUE

36
Q

How much energy is released by the hydrolysis of a single ATP molecule under cellular conditions?

A

Approximately 7.3 kcal/mol.

37
Q

What is the role of ATP in metabolism?

A

ATP transfers energy from exergonic to endergonic reactions.

38
Q

True or False: Enzymes are often compartmentalized in specific areas of the cell.

A

TRUE

39
Q

How does enzyme compartmentalization benefit the cell?

A

It increases the opportunity for enzymes and substrates to interact, speeding up reactions.

40
Q

What is a multienzyme complex?

A

A group of enzymes that work sequentially, with the product of one reaction becoming the substrate for the next.

41
Q

Where does cellular respiration primarily occur in eukaryotic cells?

A

In the mitonchondria

42
Q

True or False: All reactions catalyzed by enzymes are irreversible.

A

False. Many reactions catalyzed by enzymes are reversible.

43
Q

How does the concentration of products influence the direction of enzyme-catalyzed reactions?

A

Higher concentrations of products can drive the reaction in the reverse direction

44
Q

True or False: Catalysis by enzymes occurs at the same rate regardless of reactant concentration.

A

False. Reaction rates increase with higher substrate concentration until saturation is reached.

45
Q

What effect does pH have on enzyme activity?

A

Enzymes have an optimal pH, and deviations can reduce their activity or denature them.

46
Q

What is the lock-and-key model of enzyme specificity?

A

The enzyme’s active site is a perfect fit for the substrate, like a key fitting into a lock.

47
Q

True or False: Enzymes are highly specific and will not bind to compounds that are closely related to their substrate.

A

True

48
Q

What is the relationship between activation energy and reaction rate?

A

The lower the activation energy, the faster the reaction rate.

49
Q

What happens to an enzyme in an environment with an extremely low pH?

A

The enzyme may become denatured and lose its function.

50
Q

What is the transition state in a chemical reaction?

A

The unstable state where the reactant’s bonds have absorbed enough energy to break.

BIOL (31 decks)

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