Lecture 14: Energy Balance and Metabolism I Flashcards
Define free energy and relate to exergonic and endergonic reactions.
Difference in free energy when 1 mole of each reactant is converted to 1 mole of each product at 1 atm
Negative = exergonic reaction
Positive = endergonic reaction
Relate free energy to ATP breakdown.
Free energy is negative when ATP is broken down
Trace basic pathway for glycolysis; know where ATP and ADP is involved in the pathway. Know how galactose and glucose enter the pathway.
Galactose uses ATP to become Galactose-1-phosphate
Glucose uses ATP to become Glucose-6-phosphate
Fructose uses ATP to become Fructose-6-phosphate
Galactose and glucose can be converted to fructose-6-phosphate and enter glycolytic pathway
Describe the uptake of glucose.
Glucose is transported into the tissue cells by active sodium-glucose cotransport and facilitated transport
Be able to trace the major steps involved in glycogenesis and glycogenolysis and the enzymes involved.
Glucokinase: transfers phosphate from ATP
Phosphatase: removes phosphate
Phosphorylase: catalyzes production of glucose-1-phosphate from glycogen
Know the end products of glycolysis.
Pyruvic acid - 2
Hydrogens - 4
ATP - 2
Know the end products of the conversion of pyruvic acid to acetyl-CoA.
Acetyl-CoA - 2
Hydrogens - 4
Carbon dioxide - 2
Know the fate of pyruvic acid when oxygen is not present.
It converts to lactic acid
Be able to trace the citric acid cycle and give the major intermediates.
Net reaction: 2 Acetyl-CoA + 6H2O + 2 ADP -> 4 CO2 + 16 H + 2 CoA + 2 ATP
State where the citric acid cycle occurs in the cell.
Mitochondrial matrix
List the end products of the citric acid cycle.
Hydrogens - 16
ATP- 2
Carbon dioxide - 4
Define oxidative phosphorylation.
The oxidation of hydrogen to form more ATP
State where oxidative phosphorylation occurs.
On mitochondrial cristae
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.
Fate of hydrogens -
Hydrogens are removed in pairs
One member of each pair becomes a hydrogen ion
The other member of a pair combines with NAD+ - NADH
Fate of electrons -
Enter electron transport chain
List, in sequence, the components of the electron transport chain.
Flavoprotein
Several ion sulfide proteins
Ubiquinone
Cytochrome A3
Describe the chemiosmotic mechanism.
Electrons pass through chain, releasing large amounts of energy
Energy is used to pump hydrogen ions from inner matrix into outer chamber between inner and outer membranes
High concentration of H+ is created in chamber
Strong negative potential created in inner matrix
H+ ions flow from high to low concentration through ATP synthetase
Energy derived from H+ flow is used by ATPase to convert ADP to ATP
Describe the pentose phosphate pathway and explain what it is primarily used for.
`The pentose phosphate pathway is a cyclical pathway in which one molecule of glucose is metabolized for each revolution of the cycle
This pathway is mostly used for the synthesis of fats and other substances
Describe the transport mechanism for hydrogen ions in the pentose phosphate pathway.
Hydrogens generated from this pathway are bound to NADP+ instead of NAD+
Describe how triglycerides are synthesized from glucose.
Glucose either undergoes the glycolytic pathway or the pentose phosphate pathway.
The glycolytic pathway directly synthesizes triglycerides.
The pentose phosphate pathway synthesizes fatty acids which are then formed into triglycerides
Review the basic chemical structure of triglycerides and identify the three most common fatty acids in the human body.
Stearic acid
Oleic acid
Palmitic acid
Explain how triglycerides are absorbed from the intestinal lumen.
Most triglycerides are digested into monoglycerides and fatty acids
Intestinal epithelial cells resynthesize these into triglycerides that enter the lymph as chylomicrons
Define chylomicrons and explain how they are transported and removed from the blood. What is the role of lipoprotein lipase?
Resynthesized triglycerides that enter the lymph
Lipoprotein lipase hydrolyzes chylomicron triglycerides, releasing fatty acids and glycerol
Compare fat to carbohydrates as an energy source and explain under what conditions fat is used for energy.
Fatty acids can be used for fuel or again synthesized into triglycerides
All normal energy requirements of the body can be provided by the oxidation of fatty acids without using carbohydrates r proteins as an energy source
Conditions that increase utilization of fat for energy
-Starvation
-Diabetes mellitus
Define lipoprotein and compare the various types of lipoproteins.
Lipoproteins transport lipids in the blood
