Lecture 17: Energy Balance and Metabolism I Flashcards
Define Free energy and relate to exergonic and endergonic reactions
- Free energy
- The amount of energy liberated by complete oxidation of a food is called the free energy of oxidation
- Exergonic-
- negative change in G
- Endergonic
- positive change in G
Relate free energy to ATP breakdown
- The amount of free energy in each of the bonds of ATP is about 12,000 calories under the usual conditions of temperature and concentrations of the reactants in the body
- Trace basic pathway for glycolysis
- know where ATP and ADP is involved in the pathway
- know how galactose and glucose enter the pathway
- Galactose and glucose can be converted to fructose-6-phosphate and enter the glycolytic pathway
Describe the uptake of glucose
- via active sodium-glucose co-transport:
- active transport of sodium provides energy for absorbing glucose against a concentration gradient
- via faciliated transport:
- only transported form higher to lower concentrations
- (note the presence of insulin increases glucose transport x10)
Be able to trace the major steps involved in glycogenesis and glycogenolysis and the enzymes involved
- Enzymes
- Glucokinase
- Transfers phosphate from ATP to glucose
- Phosphatase
- Removes phosphate to allow Glucose-6-phosphate to leave cell
- Phosphorylase
- Catalyzes production of glucose-1-phosphate from glycogen
- Glucokinase
Know the end products of glycolysis
- Pyruvic acid (2 molecules)
- Hydrogen (4)
- release is catlayzed by a dehydrogenase
- ATP (2 molecules)
- 4 produced and two used means a net of 2
Know the end products of the conversion of pyruvic acid to acetyl-CoA
- Acetyl-CoA (2 molecules)
- Hydrogens (4)
- release is catalyzed by a dehydrogenase
- Carbon dioxide (2 molecules)
Know the fate of pyruvic acid when oxygen is not present
Leads to the production of lactic acid
Be able to trace the citric acid cycle and give the major intermediates
state where the citric acid cycle occurs in the cell
Occurs in the mitochondrial matrix
List the end products of the citric acid cycle
- Hydrogen (16)
- release is catalyzed by a dehydrogenase
- ATP (2 molecules)
- Carbon dioxide (4 molecules)
Define oxidative phosphorylation
the synthesis of ATP by phosphorylation of ADP for which energy is obtained by electron transport and which takes place in the mitochondria during aerobic respiration
- describe the fate of the hydrogen atoms and the electrons generated during glycolysis and the citric acid cycle
- name and compare the hydrogen ion carriers
- Hydrogens are removed in pairs
- one member of each pair becomes a hydrogen ion
- the other member of a pair combines with NAD+—-> NADH
- The fate of these electrons is that they enter the electron transport chain
List, in sequence, the components of the electron transport chain
- Flavoprotein
- several iron sulfide proteins
- Ubiquinone (Q)
- Cytochrome A3 (cytochrome oxidase)
- located on inner membrane
- can give up two electrons to oxygen
Describe the chemiosmotic mechanism
- electrons pass through chain, releasing large amounts of energy
- energy is used ot pump hydrogen ions from inner matrix into outer chamber between inner and outer membranes
- High concentration of H+ created in chamber
- Strong negative potential created in inner matrix
- H+ flow from high to low concentration through ATP synthetase
- Energy derived from H+ flow is used by ATPase to convert ADP to ATP
- For each 2 electrons that pass through electron transport chain, up to 3 ATP molecules are synthesized
- Note that the 2 pairs of hydrogens derived from the CAC enter the ETC at a later point and provide energy for 2 ATP molecules per hour.