Chapter 3/4: Bioenergetics and Exercise Metabolism Flashcards
1 g of carbohydrates yields
4 kcal of energy
1 g of fat yields
9.5 kcal of energy
1 g of protein yields
4 kcal of energy
storage form and location for carbohydrates
glycogen in the liver & muscle
define glycogenesis. performed by what enzyme?
synthesis of glycogen by glycogen synthase
define glycogenolysis. performed by what enzyme?
breakdown of glycogen to glucose by glycogen phosphorylase
define gluconeogenesis
synthesis of glucose from non-carb sources (e.g. amino acids or lactate)
define glycolysis
breakdown of glucose to pyruvate or lactate; mediated by the rate-limiting enzyme phosphofructose kinase
storage form and location for fats
stored as triglycerides in muscle and adipose tissue
define lipogenesis
synthesis of triglycerides from glycerol and free fatty acids
define lipolysis. performed by what enzyme?
breakdown of triglycerides into glycerol and free fatty acids by lipases
which component of triglycerides is not an important muscle fuel during exercise?
glycerol
define beta-oxidation
breakdown of free fatty acids to acetyl coA, which then enters the Krebs cycle
when are proteins used as an energy source?
extreme endurance races or starvation
how are proteins used as an energy source?
muscles can directly metabolize branch chain amino acids and alanine; the liver can convert alanine to glucose
define lactate shuttle
lactate produced in one tissue and transported to another is converted to acetyl-CoA and enters the Krebs cycle
define Cori cycle
lactate can be converted to glucose in the liver
how much ATP do we have in storage?
store only small amounts (~100 g) until needed; body must constantly synthesize new ATP
does the synthesis of ATP require oxygen
can occur in the presence or absence of oxygen
formula for the synthesis of ATP
ADP + Pi + energy —> ATP
formula for the breakdown of ATP
ATP + water (ATPase) —> ADP + Pi + energy
3 ATP synthesis pathways
1) ATP-PC system
2) glycolysis
3) oxidative phosphorylation
does the ATP-PC system require oxygen
no; anaerobic
ATP yield of the ATP-PC system
1 mol ATP / 1 mol phosphocreatine