3.3 Nutrition and Energy Systems

Question 1

Annotate a diagram of the ultrastructure of a generalized animal cell.

3.1

Answer 1

Question 2

Annotate a diagram of the ultrastructure of a mitochondrion.

3.2

Answer 2

Question 3

Define the term cell respiration.

3.3

Answer 3

Cell respiration is the controlled release of energy in the form of ATP from organic compounds in cells.

Question 4

Explain how adenosine can gain
and lose a phosphate molecule.

3.4

Answer 4

Bonds btw. 3 inorganic phosphate groups are very energy-rich. Energy is released when ATP molecule combines w/ water, loosing its last phosphate.

Reverse process is phosphorylation- ATP synthesized by adding phosphate group to compound adenosine diposphate (ADP)

Question 5

Explain the role of ATP in muscle contraction.

3.5

Answer 5

Muscle contraction/elongated muscle fibers require large amount of energy. Muscle fibers have biochemical capacity to produce ATP using energy sources (carbs/fats).

Nervous system stimulates muscle fibers to contract -> contractile proteins (actin & myosin) use ATP to provide chemical energy to drive contraction process.

Muscle has sufficient ATP for only 2 seconds of muscular activity, exercise longer than 2 seconds needs to come from another ATP source

• source of ATP is in biochemical pathway within muscle cell: energy system
• performance off energy systems influences contraction of muscle -> can influence performance

Question 6

Describe the re-synthesis of ATP by the ATP–CP system.

3.6

Answer 6

Creatine Phosphate (PCr)- High energy compound present in muscles.
Creatine Kinase Reaction- liberates chemical energy to synthesize ATP

• ANAEROBIC ENERGY SYSTEM
• Creatine Phosphate + ADP + H+ ↔ Creatine + ATP
• PCr broken down to provide phosphate molecule for re-synthesis of ATP that was used during initial stages of exercise (first 2 sec)
• Occurrs quickly & very important in hard exercise (e.g. sprints)
• Reaction can occur in both directions: when at rest & muscle recovers from exercise ATP can be used to refill PCr store in muscle

Question 7

Describe the production of ATP by the lactic acid system.

3.7

Answer 7

*ANAEROBIC ENERGY SYSTEM
*
Glycolysis-metabolic pathway in cytoplasm that releases energy in glucose as ATP & produces pyruvate. When oxygen is absent (high intensity exercise) or mitochondria in limited supply pyruvate is converted to lactate and 2 ATP. Small ATP supply can meet demands of high intensity exercise when PCr input fades for a short while until lactic acid accumulation reduces muscle pH -> discomfort & muscle contraction ability decreases.

Question 8

Explain the phenomena of oxygen deficit and oxygen debt.

3.8

Answer 8

Oxygen Deficit: The body needs oxygen from the moment we begin to exercise. The body gets into oxygen deficit because oxygen need and oxygen supply do not match .

Oxygen debt is now known as excess postexercise oxygen consumption (EPOC).

• EPOC: During recovery, oxygen use continues at a rate greater than what is needed at rest.
• additional oxygen demands persist during recovery, needed for processes like restoration of tissue & myoglobin oxygenation

Question 9

Describe the production of ATP from glucose and fatty acids by the aerobic system.

3.9

Answer 9

Glucose Oxidation
Glycolysis

• glucose broken down into 2 pyruvate & 2 ATP
• hydrogen ions (electrons) released

If oxygen is present, AEROBIC Energy system= Krebs cycle
* pyruvate converted to acetyl CoA which enters Krebs cycle in mitochondria
* chemical reactions convert it to water & CO2
* hydrogen ions (electrons) released

Released hydrogen ions carried to electron transport chain (ETC) by coenzymes where energy to form ATP is produced

Fat Oxidation
Fatty acid molecules enter mitochondria, beta oxidation remove 2-carbon units from fatty acid chains

• beta-oxidation enzymes in mitochondria matrix
• process produces acetyl CoA which has same fate in oxidation metabolism as that produced from glucose
• fat cant be used anaerobically

Question 10

Discuss the characteristics of the three energy systems and their relative contributions during exercise.

3.10

Answer 10

Question 11

Evaluate the relative contributions of the three energy systems during different types of exercise.

3.11

Answer 11

As exercise intensity increases, describe the change in energy requirement and provision (of ATP):

• As exercise intensity increases, so too does the requirement for ATP. At higher intensity exercise, ATP requirements immediate and in a large amount. At lower intensity exercise, ATP requirement is more slow and constant

Explain which energy systems are predominatly used for the following exercise intensities: Rest, Moderate, Brisk and Maximal

• Rest: Aerobic (Fat and Carb). Moderate: Aerobic, Anaerobic (Lactic). Brisk: Anaerobic (Lactic), Aerobic (Carb) Maximal: PCr, Anaerobic

Explain the use of Fatty Acids and Carbohydrates (Glucose) as exercise intensity increases.

• Glucose is used throughout all exercise intensities (Aerobic at low intensity, Anaerobic Lactic Acid at higher intensities. Fatty Acids are only used at lower intensity exercise. Above 90% of max exercise, no fatty acids are used as fuel.