Lecture 18: Energy Balance and Metabolism II Flashcards
How it ATP generated?
Combustion of carbohydrates, fatty acids, proteins
How is phosphocreatine used as a storage depot for energy?
Can be directly interchanged with ATP, used as storage since ATP cannot be stored
How is phosphocreatine used as an ATP buffer?
Keeps the concentration of ATP high in the presence of phosphocreatine
Essential Amino Acids
Cannot be synthesized by the body; MUST be obtained from diet
Non-essential Amino Acids
Formation depends on alpha-keto acid precursors; can be synthesized in the body
What enzyme is required to synthesize alanine from pyruvic acid?
Transaminase
What is a peptide linkage?
A bond formed between N-CO that connects amino acids, where H2O is released by condensation
How many high-energy phosphate bonds are needed to form one peptide linkage?
4 phosphate bonds
What are the resulting products of deamination?
Energy release and ammonia
Which of the following occurs in the mitochondria during the Ornithine/Urea cycle?
A. Arginine –> Urea + Ornithine
B. Citrulline + aspartate –> argininosuccinate
C. Ammonia + CO2 –> carbamoyl phosphate
D. Fumarate enters TCA cycle
C. Ammonia + CO2 –> carbamoyl phosphate
What are the 2 determinants of the chemical reaction rate?
- Concentration of enzyme
2. Concentration of substrate
How is the reaction rate influenced by high substrate concentration?
Reaction rate will be determined almost entirely by concentration of enzyme
How is the reaction rate influenced by high enzyme concentration?
Reaction rate will be directly proportional to concentration of substrate and enzyme
What is the major rate-limiting factor for almost all energy metabolism in the body?
ADP
Energy equivalent of oxygen
Energy liberated per liter of oxygen with average diet = 4.825 Cal
Basal Metabolic Rate
Minimum level of energy required for a person to “exist”; avg 70 kg male lying in bed all day uses 1650 Cal/day
How does thyroxine influence BMR?
Increases BMR by increasing reaction rates in cells
How does testosterone influence BMR?
Testosterone influences BMR 10-15%; related to increase in skeletal muscle mass
How does malnutrition influence BMR?
Results in marked reduction in metabolic rate
How does aging influence BMR?
BMR declines, related to loss of muscle mass/gain of adipose tissue
How does BMR differ between gender?
Male BMR slightly higher than female BMR; related to skeletal muscle mass
Glycogenolysis
Breakdown of glycogen to form glucose molecules
Gluconeogenesis
Formation of glucose
