chapt 3

What is metabolism?

The sum of all chemical reactions that occur in the body.

What are the two general categories of metabolic reactions?

Anabolic reactions and catabolic reactions.

What are anabolic reactions?

The synthesis of molecules.

What are catabolic reactions?

The breakdown of molecules.

What is bioenergetics?

The process of converting foodstuffs (fats, proteins, carbohydrates) into usable energy for cell work.

What are endergonic reactions?

Reactions that require energy to be added to the reactants.

What are exergonic reactions?

Reactions that release energy.

What are coupled reactions?

Reactions in which the energy released by an exergonic reaction drives an endergonic reaction.

What is oxidation?

The removal of an electron.

What is reduction?

The addition of an electron.

What happens to a molecule that loses an electron?

It is oxidized.

What happens to a molecule that gains an electron?

It is reduced.

What are enzymes?

Cellular proteins that act as catalysts to increase the speed of reactions.

How do enzymes increase the speed of reactions?

They lower the energy of activation.

What factors regulate enzyme activity?

Temperature and pH.

What do kinases do?

Add a phosphate group.

What do dehydrogenases do?

Remove hydrogen atoms.

What do oxidases do?

Catalyze oxidation-reduction reactions involving oxygen.

What do isomerases do?

Rearrange the structure of molecules.

What is glucose?

Blood sugar.

What is glycogen?

The storage form of glucose in the liver and muscle.

What is glycogenolysis?

The breakdown of glycogen to glucose.

What are fatty acids?

The primary type of fat used by skeletal muscle.

What are triglycerides?

The storage form of fat in muscle and adipose tissue.

What is lipolysis?

The breakdown of triglycerides into glycerol and fatty acids.

Is protein a primary energy source during exercise?

No, protein is not a primary energy source during exercise.

What is ATP?

Adenosine triphosphate, the universal energy source for cells.

What does ATP consist of?

Adenine, ribose, and three linked phosphates.

How is ATP synthesized?

ADP + Pi → ATP.

What are the immediate energy systems?

ATP, phosphocreatine, and the adenylate kinase (myokinase) reaction.

What are the non-oxidative energy systems?

Fast glycolysis and fast glycogenolysis.

What are the oxidative energy systems?

Oxidative phosphorylation using glucose, glycogen, fatty acids, and amino acids.

How long does stored ATP provide immediate energy?

Approximately 2 seconds.

What enzyme breaks down ATP?

ATPase.

What is phosphocreatine?

A high-energy phosphate that can rephosphorylate ADP to form ATP.

What enzyme is responsible for using phosphocreatine to rephosphorylate ATP?

Creatine kinase.

How long can phosphocreatine provide additional immediate energy?

About 10 more seconds.

What is the adenylate kinase (myokinase) reaction?

ADP + ADP → ATP + AMP.

What is fast glycolysis?

The breakdown of glucose to produce ATP and lactate.

What are the two stages of glycolysis?

Energy investment and energy generation.

How many ATP are used during the energy investment phase of glycolysis?

2 ATP.

How many ATP are produced during the energy generation phase of glycolysis?

4 ATP.

What is the net ATP production from glycolysis?

2 ATP.

What happens to one 6-carbon glucose molecule during glycolysis?

It is broken down into two 3-carbon molecules.

Where does glycolysis occur?

In the cytosol.

What is the end product of glycolysis?

Pyruvate.

What can pyruvate become under anaerobic conditions?

Lactate.

What are electron carrier molecules?

Molecules that transport hydrogens and associated electrons.

What is the reduced form of NAD?

NADH.

What is the reduced form of FAD?

FADH2.

What is the citric acid cycle also called?

The Krebs cycle.

Where does the citric acid cycle occur?

In the mitochondria.

What is the main function of the citric acid cycle?

It completes the oxidation of fuels and provides electrons for the electron transport chain.

What happens to pyruvic acid before entering the citric acid cycle?

Pyruvic acid is converted to acetyl-CoA.

What is beta-oxidation?

The process by which fatty acids are converted into acetyl-CoA.

Where does beta-oxidation occur?

In the mitochondria.

What is the electron transport chain?

A series of carriers that transfer electrons and use their energy to produce ATP.

Where does oxidative phosphorylation occur?

In the mitochondria.

How much ATP does 1 NADH produce?

2.5 ATP.

How much ATP does 1 FADH2 produce?

1.5 ATP.

What is the final electron acceptor in aerobic respiration?

Oxygen.

How many total ATP can be produced from one glucose molecule according to the lecture?

32 ATP.

What is a rate-limiting enzyme?

An enzyme that regulates the rate of a metabolic pathway.

What happens when ATP levels are high?

ATP inhibits ATP production.

What happens when ATP levels are low and ADP + Pi levels are high?

ATP production is stimulated.

What effect does calcium have on aerobic ATP production?

Calcium stimulates aerobic ATP production.

What is the rate-limiting enzyme of the ATP-PC system?

Creatine kinase.

What is the rate-limiting enzyme of glycolysis?

Phosphofructokinase (PFK).

What is the rate-limiting enzyme of the citric acid cycle?

Isocitrate dehydrogenase.

What is the rate-limiting enzyme of the electron transport chain?

Cytochrome oxidase.

What determines the contribution of aerobic and anaerobic energy systems?

The duration and intensity of exercise.

Which energy systems contribute more during short-term, high-intensity activities?

Anaerobic energy systems.

Which energy system contributes more during long-term, low-to-moderate-intensity exercise?

Aerobic energy systems.