If glucose enters cells by facilitated diffusion, it will leave the same way, so how do you keep it there?
phosphorylation
What term describes sets of enzymes that have different amino acid sequences but catalyze the same reaction?
isoenzymes
Glucokinase A. has a Km lower than the normal blood glucose concentration. B. has glucose-6—phosphatase activity. C. is found in muscle. D. is inhibited by glucose-6-phosphate. E. none of the above.
E. none of the above.
Red cells have lactate dehydrogenase primarily so that
they can regenerate NAD+ to keep glycolysis going
when liver PFK 2 is targeted by insulin, it will
become a fructose- 2,6- BP synthetase
Glucose is broken down via ______ for energy
glycolysis
Glycolysis overview
breakdown of glucose to pyruvate under aerobic condition
under anaerobic conditions, Glycolysis
produces lactate
glucose enters the cell via
facilitated diffusion
How is glucose kept in the cell?
phosphorylation
addition of phosphate makes glucose
charged
kinase that is specific for glucose
glucokinase
kinase that can phosphorylate glucose and other hexes
hexokinase
hexokinase is inhibited by
its product, G6P
glucokinase is not inhibited by G6P products which allows
liver to act as a glucose dump
glucokinase has a ___ km which means
high Km which means it has low affinity ofr glucose thus it is hard to get saturated and can bind to glucose of of the blood
Hexokinase has a ____ km which means
low km, which means that it has high affinity for glucose
not associated with obesity or high lipid levels; patients still make insulin
Type II Diabetes
MODY is associated with
mutation in Glucokinase gene
what happens to MODy in the liver
it cannot binds properly bind to glucose
MODY is also associated with genes for transcription factors that
promote insulin release
Because Mutant Glucokinase cannot take up glucose to metabolize leading to
reduced glycolysis leading to lower insulin release
ATP causes closing of ______ channel leading to _________ via rush of ______ which leads to depolarization and _____ release
ATP causes closing of K+ channel leading to depolarization via rush of calcium which leads to depolarization and insulin release
Glucose is brought into _________ via Glucokinase and undergoes _____ to create ATP
Glucose is brought into Beta-pancreatic cells via glucokinase and undergoes glycolysis to create ATP
_____ is very important in RBCs
Glycolysis
Why doe RBCs depend on glycolysis for ATP production
lack of mitochondria
glycolysis provides muscle
energy for exercise
initial exercise uses the ________ glycolysis
anaerobic
as you continue to exercise, you switch to the _______ energy system as the tissue oxygenates, which still uses glycolysis but adds the ________
As you continue to exercise, you switch to the aerobic energy system as the tissue oxygenates, which still uses glycolysis but adds the TCA cycle
_____ or _______, glycolysis produces energy in the form of ATP
Aerobically or anaerobically
glycolysis occurs in the
cytoplasm
Glucose is phosphorylated to ______ by ______ then converted to _________
Glucose is phosphorylated to G6P by hexokinase/glucokinase, then converted to F6P
F6P is ________ to make ______ which is broken down to _____ and ______, which can be interconverted
F6P is phosphorylated to make F-1,6-bisP which is broken down to G3P and DHAP, which can be interconverted
what happens in the first phases of glycolysis?
2 ATP are used to generate 2 phosphorylated 3 carbon intermediate
what must be made to generate ATP?
high energy phosphate
which enzyme shows negative cooperativity?
Glyceraldehyde 3-Phosphate Dehydrogenase
what do you need to keep glycolysis going?
NAD+
enzyme resists the loss of ____ that occurs when glycolysis is proceeding at a _____ rate as in _______ muscle
Enzyme resists the loss of NAD+ that occurs when glycolysis is proceeding at a high rate as in anaerobic muscle
reversibly accepts 2e- and 1H+ from the subtrate
NAD+
Rxn of NAD+—>NADH is a
redox rxn, beucase NAD+ is reduced and the substrate is oxidized
cells are set up to have a ____________ as it wants to have a ready supply of _______ for biological oxidation
cells is set up to have a high NAD+/NADH ratio as it wants to have a ready supply of NAD+ for biological oxidation
Niacin is derived from
vitamin B3 and synthesized also from tryptohan
deficient in niacin leads to
Pellagra
Pellagra D3 involves
dermatitis, diarrhea and dementia
D4 of pellagra?
die
action of enolase and results in
creates double bond adjacent to phosphate making high energy phosphoenolpyruvate
Pyruvate kinase generate
ATP and turns PEP into pyruvate
1,3 BPG generates
2 molecules of ATP
Net yield of ATP in glycolysis
2 ATP; 2 consumed and 4 made
lactate DH regenerates
NAD+
what happens if you run out of NAD+ during anaerobic conditions?
Cannot use ETC or TCA to regenerate NAD+
creates some important metabolites for other pathways
glycolysis
three regulated enzymes in glycolysis
hexokinase, pFK 1, pyruvate kinase
Hexokinase is inhibited by
product
what is the key regulated step in glycolysis
PFK1
PFK 1 inhibitor
ATP
PFK1 promoter
AMP
Allosteric inhibitor of PFK1
citrate
PFK1 is strongly affected by
positive regulator F-2,6-BP
Pyruvate kinase has feedforward regulation by
F-1,6-BP
Pyruvate kinase is inhibited by
phosphorylation and alanine
enzyme that controls F-2,6-BP levels
PFK2
PFK2 activates
PFK1 and glycolysis by making F-2,6-BP
PFK2 is inhibited by and what happens?
inhibited by glucagon, leading to its phosphorylation and degrading F-2,6-BP which reduces activity of PFK2 and glycolysis
Insulin activity to PFK2
drives the dephosphorylation of PFK2 and stimulates synthesis of F-2,6-BP which stimulates PFK1 and glycolysis
insulin action towards rate of glycolysis
increases
2-F-deoxyglucose targets
hexokinase
2-F-deoxyglucose is a
competitive inhibitor of hexokinase rxn.
2-F-deoxyglucose can be used
in PET imaging to find metastasis
targets glyceraldehyde 3 Phosphate DH
arsenate
targets enolase
fluoride
glycogen storage disease
Tauri’s dx
Pyruvate kinase has 4 isozymes
M1, M2, L and R
R-Pyruvate kinase is found only in
red blood cells
Tauris tx
high protein diet
Glycolytic anemia
faulty R-pyruvate kinase
muscle has _____ PFK isozyme while RBC’s have _____ isozyme
muscle has 1 and RBC’s has 3