Carbohydrates 2.0 Flashcards
Define glycolysis
Cellular reaction splitting glucose to produce ATP without requiring oxygen
Products of glycolysis
Pyruvate
or
Lactic acid
ATP
Whats doe glycolysis do
substrate level phosphorylation
Gylcolysis is essential for what
Red blood cells
and vigorously exercising muscle
Whats is the two phases to glycolysis
preparation phase
pay of phase
For 1 Glc passing through the preparatory phase what is formed
2 molecules of G-3-P
Whats is needed at preparatory phase of glycolysis
2 ATP
How much ATP is gained at payoff phase of glycolysis
4ATP
What is the NET gain of glycolysis
2 ATP
What causes phosphorylation of glucose
hexokinase
phosphohexose isomerase catalyses what
G6P - fructose 6 phosphate
When is glycolysis fixed
when fructose 1 6 biphosphate is produced as only needed for glycolysis
what causes cleavage in glycolysis
highly symmetrical arranged energised molecule that makes it easy to split and from isomers
After cleavage what is doubled and can only participate in glycolysis
glyceraldehyde 3 phosphate
preparation phase ends when
after cleavage
After cleavage end products are all
Doubled
oxidation of glyceraldehyde 3 phosphate produces what
2 NADH
phosphoglycerate kinase and pyruvate kinase catalyses what reaction in glycolysis and produces
substrate-level phosphorylation reaction
ATP
why does NAD+ need to be regenerated
limited supply in cell
the pyruvate to lactate reaction allows
regeneration of NAD+
what is the redox balance
NAD+ produced at end of glycolysis transported back to the top, always replenished
NO NAD
NO GLYCOLYSIS
where does limited NAD+ in the cell come from
niacin
what is the role of NAD+
reduction of intermediate metabolites
NADH—-> NAD+ is
dehydrogenase
Pyruvate can be dehydrogenased to
ethanol
lactate
When is pyruvate converted to lactate
cells lacking O2
Vigorously exercising muscle
RBC’s – lack mitochondria
Two enzymes catalysing pyruvate to ethanol
Pyruvate decarboxylase
Alcohol dehydrogenase
when pyruvate is converted to lactate what is oxidised
NADH
when muscles don’t receive O2 fast enough how is ATP produced
substrate-level phosphorylation
what are the product of substrate-level phosphorylation,
lactate
Lactate in converted to glucose by what process
gluconeogensis
The interaction between the liver and the muscle to produce ATP and lactate is called the
Cori cycle
Whats repays the oxygen debt to the muscles
the liver
In the presence of oxygen what is pyruvate oxidised to
acetyl coA
Where is pyruvate oxidised
mitochondria
Whats happens to the NADH when pyruvate is oxidised
later gives up Hion to respiratory chain
how many glycolysis reactions are reversible
7
Whats do irreversibel reactions have
large –ve ΔG
What is Gluconeogenesis
glucose can be generated from other non-carbohydrate molecules
what does Gluconeogenesis respond to
Hormone controls
Gluconeogenesis is not reverse glycolysis because
irreversible reactions in glycolysis is bypassed
Irreversible reaction in glycolysis are
DePhosphorylation and Phosphorylation reactions
G + ATP —> G6P
F6P + ATP —->
phosphoenoylpyruvate +ADP —> pyruvate and ATP
Glucogenesis occurs when
ATP conc is high and acetyl coA is low
In glucognesis pyruvate carboxylase synthesises what
pyruvate acid to oxaloacetate
how is oxaloacetate settled out of mitochondria
by malate
Muscle tissues difference in Gluconeogenesis is
lactate dehyrogenased to pyruvate first
what happens to G-6-P and F-1,6-bisP in Glucoeogenesis can’t be phosphorylated as is energetically unfavourable
hydrolysed
Catalyst of bypass reactions in Glucoeogenesis
Glucose 6-phosphatase
Fructose 1,6-bisphosphatase
pyruvate carboxylase
What is the end product of Glucoeogenesis and why
Glucose 6-phosphatase as traps glucose in cells
Where does the final step to make free glucose occur
the lumen
Whats happens after G-6-P is shuttled into the lumen
glucose is shuttled back into cytoplasm
where is most fructose metabolised
liver
fructose catabolised by
adipose tissue
what does the pentose phosphate pathway produce for all organisms
NADPH
pentose phosphate pathway
Converts G-6-P to a pentose phosphate (5C)
pentose phosphate is a precursor to
ATP, RNA and DNA
Whats the two parts to pentose phosphate pathway
oxidative irreversible
non-oxidative reversible
When is non oxidative phase of pentose phosphate pathway required
when lots of NADPH is needed
adipocytes generate alot of FA
Non oxidative phase is circular as
G-6-P can convert pentose phosphate then back to G6P
non reversibel oxidative phase of pentose phosphate pathway required when
Molecules need to be broken down
lots of nucleotides are required e.g. rapid cell division
When is NADP+ used for
anabolism from simple precursors inhibits oxygen (antioxidant)
When is NAD+ used
glycolysis and the citric acid cycle
is NADP+ used for metabolism?
No
Etahnol reduces glycogenesis because
uses livers supply of NAD+
what is Ethanol broken down to
acetly coA
inhibits gluconeogenesis leads to
lacticacidaemia (increased [blood lactate])
hypoglycaemia (decreased [blood Glc])
Black water fever is due to G-6-P dehydrogenase deficiency what does this cause
low RBC NADPH levels
damaging free radicals and H2O2 to build up so damages the RBC membranes
Overproduction of PEP is called
PEPCK
what does PEPCK cause
produces an overload of energy
what is the common metabolic pathway for all “fuel” molecules
Citric acid cycle
where does citric acid cycle occur
mitochondria
Does citric acid cycle produce ATP directly
No
What is the point of citric acid cycle
It removes e-’s and passes them on to form NADH and FADH2
What is acetyl coA oxidised from
pyruvate from glycolysis or fatty acids
Series of reactions of 3 subunit pyruvate dehydrogenase enzyme to form acetyl coA
decarboxylation of the pyruvate molecule,
oxidation,
transfer of the CoA
Pyruvate to acetly coA also produces
2 electrons through NADH intermediates
How many subunits does pyruvate dehydrogenase
three
what do the intermediate molecules that make up the citric cycle
constant
How many turn of the citric cycle per molecule
two
what is pyruvate dehydrogenase regulated by
ATP
To much ATP inhibits what
pyruvate dehydrogenase
what enzymes control the re-direction of cellular resources
α-ketoglutarate
isocitrate dehydrogenase
what happens when isocitrate dehydrogenase is inhibited as a control point in the citric cycle
there is build up citrate that is shuttled back into cytoplasm activating phosphofructokinase to stop glycolysis
what is the result of deactivating α-ketoglutarate in citric cycle
build up ketoglutarate which is then used for the production of amino acids
what pathway is citric acid
amphibolic pathway
what is amphibolic
serves both catabolic and anabolic processes
what happens when energy needs are met through citric acid cycle
intermediates produce the building blocks of nucleotide bases, heme groups and proteins
Build up of acetly CoA triggers what reaction
Pyruvate carboxylase converting pyruvate to oxalocaetate
What is there an increased concentration of when energy demands are met
Acetly coA
Over production of ATP cause what pathway
pyruvate to oxalocaetate to produce glucose
what is anaplerotic reactions
form the intermediates of a metabolic pathway
pyruvate to oxalocaetate to produce glucose is an example of what reaction
anaplerotic reaction
