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1st Term / PHA115 > Week 14 / Enzymes 1 > Flashcards

Week 14 / Enzymes 1 Flashcards

1
Q

Q: What are enzymes?

A

A: Specialized biological macromolecules that act as specific, efficient, and active catalysts of chemical reactions in aqueous solutions.

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2
Q

Q: What are most enzymes made of?

A

A: Most enzymes are globular proteins.

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3
Q

Q: Can enzymes be made of RNA?

A

A: Yes, some enzymes are RNA, such as ribozymes and ribosomal RNA.

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4
Q

Q: What is the main function of enzymes?

A

A: To speed up chemical reactions as highly specific and efficient catalysts.

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5
Q

Q: How are enzymes typically named?

A

A: By adding the suffix “-ase” to the name of their substrate or a word/phrase describing their catalytic action.

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6
Q

Q: On what basis are enzymes classified?

A

A: Based on the type of reaction they catalyze.

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7
Q

Q: What reaction is catalyzed by oxidoreductases?

A

A: Oxidation-reduction reactions.

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7
Q

Q: What reaction is catalyzed by transferases?

A

A: Transfer of functional groups.

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8
Q

Q: What reaction is catalyzed by hydrolases?

A

A: Hydrolysis reactions.

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9
Q

Q: What reaction is catalyzed by lyases?

A

A: Group elimination to form double bonds.

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10
Q

Q: What reaction is catalyzed by isomerases?

A

A: Isomerization.

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11
Q

Q: What reaction is catalyzed by ligases?

A

A: Bond formation coupled with ATP hydrolysis.

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12
Q

Q: What type of macromolecule are most enzymes?

A

A: Enzymes are proteins.

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13
Q

Q: What determines the specificity of an enzyme for its substrate?

A

A: The unique shape and chemical environment of the enzyme’s active site.

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13
Q

Q: What is the shape and structure of enzymes?

A

A: Enzymes have a globular shape and a complex 3D structure.

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13
Q

Q: What are metal ion cofactors?

A

A: Small inorganic ions that assist with enzyme catalysis.

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13
Q

Q: What is the role of the active site in an enzyme?

A

A: It determines which substrate(s) will bind and facilitates the catalytic reaction.

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14
Q

Q: What forms can cofactors take?

A

A: Cofactors may be:
Metal ions (e.g., Zn²⁺, Mg²⁺).

Organic/metallo-organic molecules (e.g., vitamins or coenzymes).

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15
Q

Q: What are cofactors, and why are they important?

A

A: Cofactors are non-protein “helper” molecules required by some enzymes for proper function.

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16
Q

Q: Can you name some examples of metal ion cofactors?

A

A: Examples include Mg²⁺, K⁺, Ca²⁺, Zn²⁺, Cu⁺, Co, and Fe.

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17
Q

Q: How can metal ion cofactors exist in relation to enzymes?

A

A:
Free ions: E.g., Na⁺, K⁺.
Coordination complexes: Held with the enzyme protein, e.g., Zn²⁺, Ca²⁺.

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18
Q

Q: What is the main role of metal ion cofactors in enzymes?

A

A: They assist in enzyme catalysis.

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19
Q

Q: What are coenzymes?

A

A: Organic cofactors that are loosely bound to enzymes and easily released.

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20
Q

Q: What are prosthetic groups?

A

A: Organic cofactors that are tightly bound to enzymes.

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21
Q

Q: What role do coenzymes typically play?

A

A: Coenzymes act as “co-substrates” or transient carriers of specific functional groups during enzymatic reactions.

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22
Q

Q: Where are most coenzymes derived from?

A

A: They are derived from vitamins, essential organic nutrients required in small amounts in the diet.

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23
Q

Q: Can you give examples of coenzymes and their vitamin sources?

A

A:
NAD: Derived from niacin (Vitamin B3).
FAD: Derived from riboflavin (Vitamin B2).
Coenzyme A: Derived from pantothenic acid.

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24
Q

Q: What is a holoenzyme?

A

A: The complete, catalytically active enzyme together with its bound coenzyme and/or metal ion.

25
Q

Q: What is the apoenzyme (or apoprotein)?

A

A: The protein part of an enzyme, without its coenzyme or cofactor.

26
Q

Q: Why are enzymes essential for life?

A

A: They catalyze (accelerate) biochemical reactions in the body, enabling the chemical reactions of life to occur quickly enough to sustain life.

27
Q

Q: How do enzymes affect the pace of biochemical and physiological reactions?

A

A: They speed up reactions that would otherwise proceed very slowly or not at all.

28
Q

Q: What would happen to life’s chemical reactions without enzymes?

A

A: Most reactions would occur so slowly (or not at all) that life could not exist.

29
Q

Q: What is metabolism?

A

A: The sum of all chemical reactions that take place in an organism.

30
Q

Q: What are the two main types of metabolic reactions?

A

A:

Anabolism (Anabolic reactions): Formation of bonds between molecules, catalyzed by anabolic enzymes.

Catabolism (Catabolic reactions): Breaking of bonds between molecules, catalyzed by catabolic enzymes.

31
Q

Q: What role do enzymes play in metabolism?

A

A: Enzymes catalyze cellular metabolic reactions, making them faster and more efficient.

31
Q

Q: What is anabolism?

A

A: A biosynthetic process that builds complex molecules from simpler ones.

32
Q

Q: What type of bonds are involved in anabolic reactions?

A

A: Formation of bonds between molecules.

32
Q

Q: Do anabolic reactions consume or release energy?

A

A: They are energy-utilizing processes, consuming more energy than they produce (endergonic).

33
Q

Q: What type of chemical reaction is typical of anabolism?

A

A: Dehydration synthesis reactions, which release water (e.g., carbohydrate and protein synthesis).

34
Q

Q: What is catabolism?

A

A: A degradative process that breaks down complex molecules into simpler ones.

34
Q

Q: Can you give an example of an anabolic process?

A

A: Synthesis of proteins from amino acids or carbohydrates from monosaccharides.

35
Q

Q: What type of bonds are involved in catabolic reactions?

A

A: Breaking of bonds between molecules.

36
Q

Q: Do catabolic reactions consume or release energy?

A

A: They are energy-releasing processes, producing more energy than they consume (exergonic).

37
Q

Q: What type of chemical reaction is typical of catabolism?

A

A: Hydrolytic reactions, which use water to break chemical bonds (e.g., digestion of carbohydrates).

38
Q

Q: Can you give an example of a catabolic process?

A

A: Digestion of carbohydrates into simple sugars like glucose.

39
Q

Q: What is activation energy (E)?

A

A: The initial energy required for a chemical or metabolic reaction to proceed.

40
Q

Q: Why is activation energy needed in chemical/metabolic reactions?

A

A:
To increase collisions between reactant molecules.

To shift reactant molecules into a ‘transition state’, where bonds can be broken and new ones formed.

41
Q

Q: Why can’t most metabolic reactions proceed at ambient temperature without enzymes?

A

A: Activation energy is usually too high for the reactions to occur significantly at normal body temperature.

42
Q

Q: How do enzymes help in metabolic reactions?

A

A: Enzymes lower the activation energy, allowing metabolic reactions to proceed at a faster rate.

43
Q

Q: How do enzymes function in biochemical reactions?

A

A: Enzymes act as catalysts, speeding up reactions without being consumed or chemically altered.

44
Q

Q: What do enzymes provide to lower activation energy?

A

A: Enzymes provide an alternative pathway or mechanism for the reaction.

45
Q

Q: How do enzymes interact with reactants (substrates)?

A

A: Enzymes bind to substrates and form an intermediate, which is released when the product is formed.

46
Q

Q: How do enzymes bind to their substrates?

A

A: Enzymes bind their substrates with high specificity, determined by the 3D arrangement of atoms in the enzyme’s active site.

46
Q

Q: How do enzymes affect the equilibrium of a reaction?

A

A: Enzymes accelerate the rate of the reaction without shifting or changing the equilibrium. The equilibrium is simply reached faster with the enzyme.

47
Q

Q: What is the ES complex?

A

A: The enzyme-substrate (ES) complex is formed when the enzyme binds to the substrate at its active site.

47
Q

Q: What is the ‘Lock and Key’ model of enzyme action?

A

A: The ‘Lock and Key’ model is a simplistic model where the substrate fits perfectly into the enzyme’s active site, forming weak chemical bonds, like a key fitting into a lock.

48
Q

Q: How does the substrate interact with the enzyme in the ‘Lock and Key’ model?

A

A: The substrate fits precisely into the 3D structure of the enzyme’s active site, and weak chemical bonds are formed between the substrate and the enzyme.

49
Q

Q: What is the ‘Induced Fit’ model of enzyme action?

A

A: The ‘Induced Fit’ model is a more accurate model where the binding of the substrate causes the enzyme to undergo a conformational change, leading to a tighter fit.

50
Q

Q: How does the enzyme change in the ‘Induced Fit’ model?

A

A: The enzyme changes shape when the substrate binds, bringing chemical groups into position to catalyze the reaction more effectively.

51
Q

Q: What factors affect enzyme function?

A

A:
Enzyme concentration
Substrate concentration
Temperature
pH
Salinity

51
Q

Q: How does enzyme concentration initially affect reaction rate?

A

A: As enzyme concentration increases, the reaction rate increases because more enzyme molecules lead to more frequent collisions with the substrate.

52
Q

Q: What happens to the reaction rate when enzyme concentration continues to increase?

A

A: Eventually, the reaction rate levels off because substrate concentration becomes the limiting factor, and not all enzyme molecules can find a substrate to bind to.

53
Q

Q: How does substrate concentration initially affect reaction rate?

A

A: As substrate concentration increases, the reaction rate increases because more substrate leads to more frequent collisions with the enzyme.

54
Q

Q: What happens to the reaction rate as substrate concentration continues to increase?

A

A: The reaction rate levels off when all enzyme active sites become engaged (saturated), and the maximum rate of reaction is reached.

55
Q

Q: How does temperature initially affect enzyme reaction rate?

A

A: As temperature increases, the reaction rate increases because molecules move faster, leading to more frequent collisions between the enzyme and substrate.

56
Q

Q: What happens to the reaction rate as temperature continues to increase?

A

A: At high temperatures beyond the optimum, the reaction rate decreases because the enzyme may denature, disrupting the bonds in the enzyme and between the enzyme and substrate.

57
Q

Q: What is the optimum temperature for enzyme-catalyzed reactions?

A

A: The optimum temperature is the temperature at which the reaction rate is highest, due to the greatest number of molecular collisions between the enzyme and substrate.

58
Q

Q: What happens when the temperature exceeds the optimum?

A

A: The enzyme may denature, losing its 3D shape (tertiary structure), which reduces its ability to bind to the substrate.

1st Term / PHA115 (37 decks)

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