CH 10 Metabolism EXAM 1

Question 1

Define metabolism.

Answer 1

Metabolism is the sum of all the chemical reactions in a cell.

Question 2

Describe anabolism.

Answer 2

Anabolism is the buildup of small molecules to create large molecules, requiring energy (endergonic). Examples include photosynthesis, DNA synthesis, and protein synthesis.

Question 3

Explain catabolism.

Answer 3

Catabolism is the breakdown of large molecules into small molecules, releasing energy (exergonic). Examples include glycolysis and the Krebs cycle.

Question 4

How do anabolism and catabolism differ?

Answer 4

Anabolism involves the buildup of small molecules into large molecules and is endergonic, while catabolism involves the breakdown of large molecules into small molecules and is exergonic.

Question 5

What role do enzymes play in metabolism?

Answer 5

Enzymes are needed in both anabolism and catabolism as they speed up chemical reactions.

Question 6

Describe dehydration synthesis.

Answer 6

Dehydration synthesis is a reaction that synthesizes a polymer by losing water, resulting in a longer polymer.

Question 7

Explain hydrolysis.

Answer 7

Hydrolysis is a reaction that breaks down a polymer by using water to break a bond, adding a water molecule in the process.

Question 8

How does energy change in anabolism?

Answer 8

In anabolism, energy is required, making it an endergonic process.

Question 9

How does energy change in catabolism?

Answer 9

In catabolism, energy is released, making it an exergonic process.

Question 10

Describe hydrolysis in the context of polymers.

Answer 10

Hydrolysis is the process of breaking down a polymer by using a water molecule to break a bond.

Question 11

How do enzymes affect chemical reactions in the body?

Answer 11

Enzymes speed up reactions by acting as organic catalysts and lowering the activation energy required for a chemical reaction.

Question 12

Define the characteristics of enzymes.

Answer 12

Enzymes are primarily made of proteins, speed up reactions, lower activation energy, have a unique shape and specificity, possess an active site for substrate binding, are not used up in reactions, can be reused, can be regulated, and are subject to denaturation.

Question 13

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

Answer 13

The active site is the region on the enzyme where the substrate binds, facilitating the chemical reaction.

Question 14

Explain the difference between apoenzyme and holoenzyme.

Answer 14

An apoenzyme is the inactive protein component of an enzyme, while a holoenzyme is the active form, consisting of the apoenzyme plus a cofactor.

Question 15

How do cofactors and coenzymes assist enzymes?

Answer 15

Cofactors are non-protein molecules, often metal ions like iron or zinc, that assist enzyme function, while coenzymes are organic molecules, often vitamins, that help enzymes work properly.

Question 16

Describe how enzymes are generally named.

Answer 16

Enzymes are typically named based on their substrate or the reaction they catalyze, such as lactase for lactose or polymerase for DNA.

Question 17

What are exoenzymes and endoenzymes?

Answer 17

Exoenzymes are enzymes that act outside the cell, while endoenzymes function within the cell.

Question 18

How can enzymes be regulated?

Answer 18

Enzymes can be regulated through various mechanisms, including the presence of inhibitors or activators that affect their activity.

Question 19

What happens to enzymes during denaturation?

Answer 19

During denaturation, enzymes lose their unique shape and functionality, often due to changes in temperature or pH.

Question 20

Describe the function of exoenzymes.

Answer 20

Exoenzymes are involved in breaking down large, complex molecules into smaller subunits that can be easily absorbed by the cell.

Question 21

Define endoenzymes and their role in cellular processes.

Answer 21

Endoenzymes are enzymes that function inside the cell, catalyzing reactions necessary for normal cellular processes.

Question 22

How do constitutive enzymes differ from regulated enzymes?

Answer 22

Constitutive enzymes, like those in glycolysis, are always present and ready to function, while regulated enzymes, such as the Lac operon in E. coli, are only produced or activated when needed.

Question 23

Explain feedback or end-product inhibition.

Answer 23

Feedback or end-product inhibition occurs when the final product of a metabolic pathway blocks an early reaction, shutting down the entire series to prevent waste.

Question 24

Describe competitive inhibition in enzyme activity.

Answer 24

In competitive inhibition, a normal substrate competes with a competitive inhibitor for the active site of an enzyme. If the substrate wins, the reaction proceeds; if the inhibitor wins, the reaction is blocked.

Question 25

What is non-competitive inhibition?

Answer 25

Non-competitive inhibition occurs when an inhibitor binds to an allosteric site on the enzyme, changing its shape and preventing the substrate from binding to the active site.

Question 26

Define an allosteric site in the context of enzyme function.

Answer 26

An allosteric site is a unique region of an enzyme, distinct from the substrate binding site, that influences the enzyme’s catalytic activity.

Question 27

How does penicillin act as a competitive inhibitor?

Answer 27

Penicillin acts as a competitive inhibitor by competing with the normal substrate for the active site of the enzyme, blocking the reaction.

Question 28

What role do heavy metal ions play in non-competitive inhibition?

Answer 28

Heavy metal ions act as non-competitive inhibitors by binding to the allosteric site of an enzyme, altering its shape and preventing substrate binding.

Question 29

Explain the significance of PFK in glycolysis regarding feedback inhibition.

Answer 29

PFK (phosphofructokinase) is an example of feedback inhibition, where the final product binds allosterically to inhibit an early step in glycolysis, preventing wasteful reactions.

Question 30

Describe protein denaturation and its effects on proteins.

Answer 30

Protein denaturation refers to the loss of a protein’s native structure, resulting in a biologically inactive protein.

Question 31

Identify factors that can lead to protein denaturation.

Answer 31

Factors that can denature a protein include physical and chemical conditions such as pH, salt concentration, temperature, and other environmental factors.

Question 32

Define oxidation and reduction in terms of electron transfer.

Answer 32

Oxidation is the loss of electrons, while reduction is the gain of electrons.

Question 33

Explain the role of coenzymes NAD+ and FAD in electron transfer.

Answer 33

NAD+ and FAD are involved in electron transfer by stripping glucose of electrons and adding hydrogen, forming NADH and FADH2, which transfer H+ electrons to the electron transport system to produce ATP.

Question 34

How does ATP function as an energy molecule?

Answer 34

ATP is a good energy molecule because it packs a lot of energy, storing significant potential energy within the strong covalent bonds between its phosphate groups.

Question 35

Differentiate between substrate-level phosphorylation and oxidative phosphorylation.

Answer 35

Substrate-level phosphorylation is less efficient and involves directly transferring a phosphate group from a high-energy substrate molecule to ADP to produce ATP, as seen in glycolysis and the Krebs cycle.

Question 36

Describe the process of oxidative phosphorylation.

Answer 36

Oxidative phosphorylation uses the energy from electron transfer along the electron transport chain to create a proton gradient, which drives ATP synthesis through ATP synthase. It requires oxygen.

Question 37

Define glycolysis and its key characteristics.

Answer 37

Glycolysis is a metabolic process that starts with glucose (a 6-carbon molecule) and occurs in the cytoplasm. It produces a net of 2 ATP and 2 NADH, is anaerobic, and results in 2 pyruvate. It involves substrate-level phosphorylation.

Question 38

How many ATP and NADH are produced in glycolysis?

Answer 38

Glycolysis produces a net of 2 ATP and 2 NADH.

Question 39

Where does glycolysis occur in the cell?

Answer 39

Glycolysis occurs in the cytoplasm.

Question 40

What is the end product of glycolysis?

Answer 40

The end product of glycolysis is 2 pyruvate.

Question 41

Explain the transition reaction and Kreb’s cycle.

Answer 41

The transition reaction and Kreb’s cycle start with pyruvate and occur in the mitochondria. They produce a net of 2 ATP and 8 NADH, and involve substrate-level phosphorylation.

Question 42

How many ATP are produced in the transition reaction and Kreb’s cycle combined?

Answer 42

The transition reaction and Kreb’s cycle combined produce a net of 2 ATP.

Question 43

What type of phosphorylation occurs during glycolysis?

Answer 43

Glycolysis involves substrate-level phosphorylation.

Question 44

How many NADH are produced in the transition reaction and Kreb’s cycle?

Answer 44

The transition reaction and Kreb’s cycle produce a total of 8 NADH.

Question 45

Where does the transition reaction and Kreb’s cycle take place?

Answer 45

The transition reaction and Kreb’s cycle take place in the mitochondria.

Question 46

What is the starting material for the transition reaction?

Answer 46

The starting material for the transition reaction is pyruvate.

Question 47

Describe the role of oxygen in oxidative phosphorylation.

Answer 47

Oxygen acts as the final electron acceptor in oxidative phosphorylation.