Metabolism 1 & 2 Flashcards
Four fates of acetyl coA
Lipogenesis
Cholesterol synthesis
Formation of ketone bodies
TCA cycle
What type of reaction is the TCA cycle?
Combustion reaction: produces H20, CO2, and ATP
Where does beta-oxidation take place?
In the mitochondria
What structures have the highest stores of glycogen?
Liver, heart/skeletal muscle
How does amino acid metabolism lead to TCA cycle propagation?
Proteins can be broken down either to acetyl coA or to an intermediate in the TCA cycle
Driving force for the coordination of metabolism
To provide the brain with glucose. (That and ketone bodies [during starvation] are the only source of fuel for the brain)
Hydration status in stored macromolecules
Proteins and carbohydrates are stored in a hydrated state; lipids are stored in an anhydrous state
Ratio of pancreatic amylase release to the amount of starch intake
There is a large excess of the enzyme released relative to the amount ingested
Relative amounts of sucrase and lactase
Sucrase is generally in great excess; lactase is less abundant
Products of bacterial breakdown of lactose left in the lumen
Lactic acid, methane, carbon dioxide, and hydrogen gas
How many mutations of the LCT gene have been identified?
9
Lactose anaphylaxis
Milk-induced allergic reaction in response to alpha S1 casein
Secondary lactose intolerance
Present in children who have recently had gastroenteritis that caused damage to the epithelial lining of the gut; once the epithelial lining is healed, the symptoms resolve
What long-term effects does insulin have on metabolism?
Glycolysis and glycogen synthesis
Net products of glycolysis
2 pyruvate, 2 ATP, 2 NADH, and 2 water
Daily glucose usage in the brain vs muscle
120 g vs 40 g
Where are the only glucagon receptors located?
On the liver
Fate of lysed glycogen in the liver
Once the glycogen is cleaved into G6P, the liver does not use it
Products of the pentose phosphate pathway
NADPH and ribose-5-phosphate
Red blood cell metabolism
They lack a nucleus and mitochondria, so they depend 100% on glycolysis
Function of GLUT2 having lower affinity for glucose
All the other GLUT transporters are saturated at normal concentrations of glucose; this allows GLUT2 to be the “override” transporter that is present for excess glucose after a carbohydrate-rich meal
Functional components of GLUT transporters
12 membrane-spanning helices with intracellular loop between 6th and 7th helices
How much of glucose is metabolized in an insulin-independent manner?
70%
Three mechanisms of regulation of regulatory enzymes in glycolysis
Allosteric in/activation, covalent modifications, and regulation of enzyme synthesis
Three regulated enzymes in glycolysis
Hexokinase/glucokinase
PFK-1
Pyruvate kinase
Glycolysis produces energy in the form of ___
NADH and ATP
What can pyruvate be used for in the presence of sufficient energy?
Can be used in protein synthesis
Significance of first phosphorylation step
Once glucose is phosphorylated, it is trapped inside the cell and will continue metabolism in one way or another
Most highly regulated step of the glycoloysis pathway
Aldolase A (splits F16BP into dihydroxyacetone phosphate and glyceraldehyde 3 P)
Deficiency of any of the glycolytic enzymes
Red blood cells become swollen and they burst, causing hemolytic anemia
Substrate-level phosphorylation during glycolysis
Occurs during the step where 13BPG is converted to 3PG by phosphoglycerate kinase
Glycolytic enzymes producing ATP
Pyruvate kinase and phosphoglycerate kinase
Three stages of glycolysis
Stage 1: prepping stage
Stage 2: splitting stage
Stage 3: oxidoreduction/phosphorylation stage
Allosteric regulation
Activates or inhibits enzyme activity; products of the enzyme will allosterically inhibit the enzymes in glycolysis, whereas substrates will activate them. Transient and easily reversible.
Covalent modification
In/activation of an enzyme based on phosporylation
Enzyme synthesis based on translation stability
Long-term control of enzyme activity
