EXSS 376- Exam 1 (Metabolism) (Energy Breakdown/Bioenergetics)

exercise physiology

the study of how the body’s function and structure are altered acutely and chronically in response to physical activity

acute

the changes in human physiology that occur during exercise or physical activity

chronic

the alterations/adaptations in the structure and functions of the body that occur in response to regular participation in physical activity and exercise

energy

the performance of Work

bioenergetics

flow and energy exchange within a living system

metabolism

all the chemical reactions in the body

chemical biological work

biosynthesis of cellular molecules; e.g. glucose to glycogen

mechanical biological work

muscle contraction; e.g. elbow flexion

transport biologic work

transfer of substances among cells; e.g. electron transport chain

endergonic

chemical reactions that store or absorb energy with free energy increase for biologic work (uphill process)

exergonic

any physical or chemical process that releases energy to surroundings with free energy decline (downhill process)

energy release can be calculated from ____ produced

heat

1 calorie (cal) = the heat energy required to raise 1 g of water from ____ to ____ ( _degree)

14.5 to 15.5; 1

how many kcals does 1,000 cals equal?

1

1,000 cals equal how many dietary Calories?

1

if there is more available substrate, what happens to pathway activity?

it is increased or higher

if there is excess of a given substrate, what happens?

cells rely on that substrate more than others

what do enzymes do?

facilitate breakdown of substrates; lower activation energy needed for a chemical reaction

coenzymes

nonprotein organic substances that facilitate enzyme action by binding a substrate to its specific enzyme

what are factors that affect the rate of bioenergetics? (3)

• specific enzymes required

• more enzyme activity = more product

• rate limiting enzymes

rate-limiting enzyme

enzyme that has the important function to control the reactions overall rate; typically early in the reaction pathway

what sort of feedback loop affects bioenergetics?

negative

what are the three substrates used for fuel?

• carbohydrates

• fat

• protein

what substrate is commonly used for short/high intensity exercise?

carbohydrates

what substrate is commonly used for long exercise?

carbohydrates, with some fats

what are common macronutrient fuel sources? (6)

• triglycerol and glycogen molecules stored in muscle cells

• blood glucose

• free fatty acids

• intramuscular and liver derived carbon skeletons of amino acids

• anaerobic reactions in the initial phase of glucose breakdown

• PCr phosphorylates ADP under enzyme control

what three structures make up ATP?

• triphosphate

• ribose

• adenine

• ribose + adenine = adenosine

what catalyzes the breakdown of ATP and water to ADP and phosphate?

ATPase

why must ATP be continually resynthesized?

cells can only contain and store small quantities of ATP

what are the three ATP synthesis pathways?

• ATP-PCr system

• Glycolytic system

• Oxidative system

Is the ATP-PCr system anaerobic or aerobic?

anaerobic

Is the glycolytic system anaerobic or aerobic?

anaerobic

Is the oxidative system anaerobic or aerobic?

aerobicwh

where do anaerobic pathways typically occur in the cell?

the cytosol

where do aerobic pathways typically occur in the cell?

the mitochondria

what substrates typically undergo glycolysis in the cytosol? (4)

• Phosphocreatine

• Glucose/glycogen

• Glycerol

• Some deaminated amino acids

what substrates typically undergo aerobic pathways in the mitochondria? (3)

• Fatty acids

• Pyruvate from glucose

• Some deaminated amino acids

Do cells store more PCr or ATP?

PCr (4-6 times)

how long does it take the ATP-PCr system to reach its maximum energy yield?

3-15 seconds

what catalyzes the ATP-PCr system?

creatine phosphokinase (CK)

what happens to CK activity when ATP levels decrease?

CK activity increases

what happens to CK activity when ATP levels increase?

CK activity decreases

glycolysis

glucose breakdown

glycogenolysis

glycogen breakdown

gluconeogenesis

the formation of glucose from a non-sugar pre-cursore

what are common non-sugar pre-cursors used in gluconeogenesis? (3)

• lactate

• pyruvate

• amino acids

glycogenesis

glycogen synthesis

anaerobic (fast) glycolysis

results in pyruvate-to-lactate formation with the release of about 5% of energy within the original glucose molecule

aerobic (slow) glycolysis

results in pyruvate-to-acetyl-CoA-to-citric acid cycle and electron transport of the remaining energy within the original glucose molecule

what does glucose or glycogen convert to before glycolysis?

glucose-6-phosphate

about how many enzymatic reactions occur during anaerobic glycolysis?

10-12

what is the ATP yield for anaerobic glycolysis?

• 2 ATP for glucose

• 3 ATP for glycogen

about how long does anaerobic glycolysis sustain energy needs for all-out/high intensity activity?

15sec-2min

what are the three enzymes glycolysis is regulated by?

• hexokinase

• pyruvate kinase

• phosphofructokinase (PFK)

what is the rate limiting enzyme for glycolysis?

phopofructokinase (PFK)

what happens to PFK activity when ATP levels decrease?

PFK activity increases

what happens to PFK activity when ATP levels increase?

PFK activity decreases

what other two factors (not enzymes) regulate anaerobic glycolysis?

• Fructose 1, 6-biphosphate levels

• Oxygen abundance

can lactate be re-used as an energy source?

yes

what are the tree ways lactate can be used?

• lactate produced in the cytoplasm can be taken into the mitochondria and oxidized

• lactate can be transported via MCT transporters to other cells and oxidized there (lactate shuttle)

• lactate can recirculate back to the liver and be reconverted to pyruvate and then to glucose through gluconeogenesis

what is the process in which lactate is reconverted to pyruvate and then to glucose?

the Cori Cycle

what is the ATP yield for a glucose molecule that undergoes oxidation?

32-33 ATP

what is the ATP yield for a triacylglycerol that undergoes oxidation?

> 100 ATP

how many steps are in the Kreb’s cycle?

11

what are the two phases of aerobic glycolysis?

• citric acid cycle

• electron transport chain

what does pyruvate from anaerobic glycolysis convert to at the start of aerobic glycolysis?

Acetyl-CoA

oxidative phosphorylation synthesizes ATP by transferring electrons from ____ and _____ to oxygen

NADH; FADH2

what is the rate limiting enzyme for oxidative phosphorylation?

Isocitrate dehydrogenase

Around what step of the citric acid/krebs cycle does isocitrate dehydrogenase do its job?

step 5

what does a triglyceride breakdown to?

1 glycerol + 3 fatty acids

what yields more ATP: fat or glucose?

fat

what is faster: fat oxidation or glucose oxidation?

glucose oxidation

what stimulates the breakdown of triacylglycerol?

hormone-sensitive lipase

beta-oxidation

a series of steps where two-carbon acyl units are cleaved from a free fatty acid and then converted into acetyl-CoA for oxidation

what hormones effect the process of lipolysis? (4)

• epinephrine

• norepinephrine

• glucagon

• growth hormone

what two things can amino acids be converted to for energy?

• glucose (gluconeogenesis)

• acetyle-CoA