metabolism overview and glycolysis Flashcards
catabolism
-break down of fuels into useable forms of energy
-energy generated by oxidation of carbon to CO2 using O2
-coupled with generation of reducing equivalents
anabolism
-biosynthesis of molecules from smaller molecules
-requires input of energy (ATP or NADPH)
biochemical reactions ae commonly regulated by ______ or _______ control
feedback or feedforward
rate-limiting or commitment steps?
-where metabolic regulation usually occurs
-rate-limiting steps: the slowest step in the pathway
-commitment steps: the first irreversible step unique to the pathway (usually has high energy substrates like ATP)
what is a futile cycle? give one example
-formed by irreversible reactions in opposite directions
-activation of both reactions would waste cellular energy
-minimize energy loss, reactions only in one direction should be active at given time (glycolysis vs glucogenesis)
-liver uses between glucose and glucose 1 phosphate to maintain blood glucose levels
regulation of metabolism
-transcriptional/translational regulation (slow)
-protein degradation (slow)
-allosteric regulation (fast)
-post translational modification (fast)
-compartmentation (fast)
transcription/translational regulation
-slow
-induction of genes
protein degradation
-slow
-ubiquitin-proteasome pathway
-lysosomal proteolysis
post translational modification
-fast
-phosphorylation
allosteric regulation
-activators and inhibitors
-fast
compartmentation
-fast
-shuttling substrates to a compartment for biochemical reactions
-fatty acid biosynthesis in the cytosol and oxidation in the mitochrondria
difference in metabolism between organs
-different organs utilize metabolic pathways to perform their functions
-organs cooperate tightly to optimize the systemic physiological responses to nutritional status, physical activity, etc
glycolysis overview
-happens in the cytosol
-input: glucose
-output: 2 pyruvate
-energy harvested: 2 ATP and 2 NADH
_______ increases the number of glucose transporters on the cell membrane
insulin
except on the liver
reactions coupled with ATP hydrolysis are usually_____
irreversible
glucose 6 phosphate is also used in __________ and _______
glycogen synthesis and pentose phosphate pathway
the production of ______ is the commitment step of glycolysis
fructose 1-6 bisphosphate
AMP as signaling molecule
-ATP, ADP, and AMP are maintained in equilibrium in cytosol
-[ATP]»[ADP]»[AMP]
-small decrease in [ATP] results in significant increase in [AMP]
-cells sense its energy status using AMP as signal
-AMP activated protein kinase. has a critical role in cellular energy homeostasis
____ steps are rarely regulated
reversible
enzymes keep the reactions near _____
equilibrium
Fructose 1,6 bisphosphate activates pyruvate formation through
feedforward control
pyruvate is also used to make alanine
pyruvate
-product of glycolysis
-transported to mitochondria for the conversion to acetyl CoA
-can be used to make glucose through gluconeogenesis
glycogen synthesis and breakdown
-liver and muscles store excess glucose as glycogen
-glycogen synthesis and breakdown are tightly regulated
-liver regulates blood glucose levels using glycogen
utilization of fructose
-fructose does not increase blood insulin levels
-requires different kinases from glycolysis
-same splitting enzyme as glycolysis is used, but fructose 1 phosphate is poor substrate for enzyme
-excess amounts will accumulate in liver, depleting ATP and phosphate, causing sever liver damage
Which of the following metabolites cannot be a carbon source for gluconeogenesis
pyruvate
lactate
alanine
acetyl coa
acetyl CoA
