Exam 3: Glycolysis Flashcards
What is a catabolic reaction
break down large molecules to smaller
extracts energy
anabolic reaction
small molecules into larger molecules, require energy input
Is glycolysis anaerobic or aerobic
anaerobic
What are the 2 stages of glycolysis
stage 1 energy input (2ATP used)
stage 2 energy output (use 2 ATP, produces 4ATP)
What kind of reaction is reaction 2 in glycolysis
glucose-6-phosphate –>
isomerization reaction
What is the first energy OUTPUT reaction in glycolysis (use diagram)
reaction 7:
glycerate 1,3 bisphosphate –>
What kind of reaction is ADP–>ATP
substrate level phosphorylation, a phosphate is taken from a substrate and transferred to ADP to produce ATP
What are the anaerobic and aerobic fates of pyruvate
anaerobic: fermentation
aerobic: CAC–>ETC
What is a better way to get energy from pyruvate? Fermentation or anaerobic glycolysis
anaerobic glycolysis
What is homolactic fermentation and when does it happen
pyruvate is transformed into lactate. Can be done during intense exercise
What is the purpose of fermentation
to regenerate NAD from NADH without using O2 allowing glycolysis to continue
Why does intense exercise cause muscle cramping?
because you build up lactate during homolactic fermentation making the pH levels go down and causing proteins to denature in muscles
What enzyme catalyzes homolactic fermentation
LDH lactate dehydrogenase
When does alcohol fermentation happen?
in bacteria, yeast.
What enzyme catalyzes alcohol fermentation
PDC pyruvate decarboxylase
Why can’t humans ferment alcohol?
We dont have the PDC enzyme encoded in our DNA.
What enzyme do humans have to break down alcohol when drinking, where is it what does it do
ADH1 alcohol dehydrogenase 1, in our gut, converts ethanol into acetyl aldehyde and regenerates NAD+ from it, NADH–> NAD+
what are the 3 places energy is -delta G in glycolysis in RBCs
hexokinase, PFK-1, pyruvate kinase.
Where are hexokinases 1-3 located
in the mitochondrial membrane
Talk about the affinity and inhibitors of hexokinase 1-3
small km, higher affinity for glucose
all inhibited by G-6-p
Where is hexokinase 4 located
liver, pancreas, intestine, brain
Talk about the affinity and inhibitors of hexokinase 4
larger km, less affinity for glucose, no inhibited by G-6-p, needs higher glucose concentration to be activated
what happens to glucose in pancreas and liver
liver: stores excess glucose
pancreas: acts as glucose monitor to signal insulin secretion
What does glucokinase or GK do
initiated by higher levels of glucose, binds to glucokinase regulatory protein GKRP, complex goes into nucleus and dissociated or separates, signals insulin secretion.
When and why is glucagon secreted
produced by alpha cells in pancreas, secreted when glucose levels are low
How does glucagon affect glycolysis and gluconeogenesis
causes glycolysis to slow down and gluconeogenesis to speed up. binds to receptor causing adenylate cyclase in membrane to activate it, catalyzes ATP–> CAMP. CAMP binds to PKA and activates it
When and why is insulin secreted
secreted by pancreatic beta cells when glucose levels are high
How does insulin affect glycolysis and gluconeogensis
binds to a receptor, activates ppp, increases glycolysis and decreases gluconeogenesis
Where does gluconeogenesis occur in the body
only in the liver
Where in the cell does gluconeogenesis occur
1st step in mitochondrial matrix, the rest in cytosol
What are the non carbohydrate progenitors of gluconeogenesis
pyruvate, lactate, glycerol and some AAs
What are the 3 places gluconeogenesis is different from glycolysis
hexokinase, PFK-1, pyruvate kinase
Explain the OAA oxaloacetate/ malate shuttle
a transport system to move OAA in the mitochondria to the cytosol to be converted into PEP, malate is a protein transporter that carries it across. NAD+–> NADH to bind in mitochondria. Vice versa to separate once crossed to cytosol.
What does the Cori cycle do
transports lactate from muscle to liver to go through gluconeogenesis
What is cortisol, when is it released, what does it do
steroid hormone that is released in response to stress, causes increase in gluconeogenesis enzyme. a type of longer term control
What are the 2 enzymes used in glycogen synthesis
phosphoglucomutase and glycogen synthase
Is glycogen synthesis creating any energy? Why?
no, a delta G=0 reaction because ultimately UDP is given back,
What enzyme is needed for glycogen degradation
glycogen phosphorylase
Describe glycogen degradation
glucose is taken off of non reducing end of glycogen chain by glycogen phosphorylase, bond is replaced by phosphate (not from ATP), glycogen is converted into G-1-P
How are glucagon and glycogen degradation/synthesis related
glucagon is released when blood glucose levels are low, causes more glycogen breakdown, producing more glucose
How are Insulin and glycogen degradation/synthesis related
insulin is released at high glucose levels, causes less glycogen breakdown and more glycogen synthesis
Who does epinephrine act like and what does it do to the glycogen synthesis/degradation process
acts like glucagon, activates adenyl cyclase and increases glycogen breakdown, decreases glycogen synthesis
In glycolysis __ moles of ATP are produced per mole of glucose
2 ATP
In anaerobic organisms pyruvate is used to regenerate cellular
NAD+
In animals excess glucose is stored as
glycogen
