TBL6 Metabolic Pathway Flashcards
Glycolysis occurs in the _____ of the cell.
cytosol
Glycolysis is an (aerobic/anaerobic) process.
anaerobic (does not require oxygen)
______ involves the formation then splitting of a high energy compound in 10 steps.
Glycolysis
The first step of glycolysis:
(Enzyme) will catalyse the transfer of a phosphate group from ATP to glucose, forming _______.
Hexokinase; forming glucose-6-phosphate
Second step of glycolysis:
Glucose-6-phosphate will be isomerised to form ________, by (enzyme).
Forms fructose-6-phosphate; catalysed by phosphoglucose isomerase
Third step of glycolysis:
(Enzyme) will then transfer a phosphate group from ATP to fructose-6-phosphate, forming ___________.
Phosphofructokinase; forming fructose-1,6-bisphosphate
4th step of glycolysis:
Fructose-1,6-bisphosphate will then be cleaved by (enzyme) to form ______________ and __________.
Cleaved by aldolase; forming
1) glyceraldehyde-3-phosphate
2) dihydroxyacetone phosphate (DHAP)
5th step of glycolysis:
Dihydroxyacetone phosphate (DHAP) will be converted into _________ by (enzyme).
converted into glyceraldehyde-3-phosphate; catalysed by triose phosphate isomerase (TPI)
____ deficiency can cause lower concentration of GALP in cells, making cellular respiration inefficient.
Triose phosphate isomerase (TPI)
6th step of glycolysis:
Glyceraldehyde-3-phosphate (GALP) will undergo oxidation by (enzyme) to form __________.
During this process, ______ is produced by reduction.
catalysed by GALP-dehydrogenase; forming 1,3-bisphophoglycerate
NADH is produced (from NAD+).
7th step of glycolysis:
1,3-bisphophoglycerate then undergoes _______ phosphorylation to form 3-phosphoglycerate, catalysed by (enzyme).
Formation of ATP also occurs.
substrate-level phosphorylation;
catalysed by phosphoglycerate kinase
8th step of glycolysis:
3-phosphoglycerate is then converted to __________ by (enzyme).
2-phosphoglycerate; catalysed by phosphoglycerate mutase
9th step of glycolysis:
2-phosphoglycerate then undergoes _______ by (enzyme) to form phosphoenolpyruvate.
dehydration by enolase
10th step of glycolysis:
Phosphoenolpyruvate then undergoes ________ phosphorylation to form ______. This reaction is catalysed by _________.
substrate-level phosphorylation; forming pyruvate;
enzyme: pyruvate kinase
The net products of glycolysis from one molecule of glucose are:
2 NADH, 2 ATP
Does substrate-level phosphorylation require oxygen?
No
After glycolysis, pyruvate can undergo three different pathways under varying conditions:
1) Alcoholic fermentation
2) Lactate fermentation
3) Link reaction to acetyl-CoA
In alcoholic fermentation,
pyruvate is first converted to _______ by the enzyme ________.
After which, the intermediate is converted to ethanol by the enzyme _________.
___ is regenerated in the process.
Pyruvate is first converted to ethanal by pyruvate decarboxylase via a decarboxylation reaction.
Ethanal is then reduced to form ethanol, catalysed by alcohol dehydrogenase.
NAD+
In lactic acid fermentation,
pyruvate is reduced to lactate by (enzyme). ___ is regenerated in the process.
enzyme: lactate dehydrogenase
NAD+ regenerated
Alcoholic fermentation is (reversible/irreversible).
irreversible
–> Ethanol CANNOTbe converted back to pyruvate once oxygen is available.
Lactate fermentation is (reversible/irreversible).
reversible
–> Lactate can be converted back to pyruvate in the liver to continue aerobic respiration.
________ is an important source of ATP in muscles which buffers the demand for ATP during intense exercise.
Creatine phosphate
(Enzyme) will convert creatine phosphate to creatine. It transfers the phosphate group on creatine phosphate to ADP, forming ATP.
Creatine kinase
The link reaction occurs in the _______.
mitochondrial matrix
The pyruvate dehydrogenase complex consists of 3 enzymes: ?
1) Pyruvate decarboxylase
2) Lipoamide-reductase transacetylase
3) Dihydrolipoyl dehydrogenase
The prosthetic group of Pyruvate Decarboxylase enzyme (part of the pyruvate dehydrogenase complex) is:
Thiamine pyrophosphate (TPP)
The prosthetic group of Lipoamide-reductase transacetylase is:
Lipoamide
The prosthetic group of Dihydrolipoyl dehydrogenase is:
FAD
______ is a Vitamin B1 deficiency resulting in damaged PNS, muscle weakness and decreased cardiac output.
This is due to the inability to form ____.
Beri-beri; TPP
The first step of the link reaction:
TPP of the pyruvate carboxylase will attack pyruvate and form __________.
Hydroxyethyl-TPP
2nd step of the link reaction:
Oxidation and transfer of _______ to lipoamide to form __________.
Lipoamide is reduced in the process.
Transfer acetyl group to lipoamide to form acetylipoamide
3rd step of link reaction:
Transfer of _____ group to CoA to produce _______.
Transfer of acetyl group to CoA to form acetyl CoA.
4th step of link reaction:
Regeneration of oxidised lipoamide by transferring protons to _____ to form _____.
Reduced lipoamide transfers protons to FAD to form FADH2.
5th step of link reaction:
Regeneration of oxidised FAD by transferring protons to ____ to form NADH.
NAD+
The products of the link reaction are:
2 acetyl-CoA
2 NADH2
2 CO2
Acetyl-CoA has a ______ bond which is a high energy linkage that is readily hydrolysed, allowing acetyl-CoA to donate the acetyl group to other molecules.
thioester bond
The Krebs’ cycle occurs in the _________.
mitochondrial matrix
Can Krebs’ cycle operate under anaerobic conditions?
No
The final products of the Krebs’ cycle per glucose molecule are:
2 FADH2
6 NADH
4 CO2
2 ATP
All enzymes involved in the Krebs’ cycle are soluble proteins in the mitochondrial matrix, except for ________ which lies on the inner mitochondrial membrane.
succinate dehydrogenase
1st step of TCA cycle:
Acetyl-CoA transfers the acetyl group to _______, forming _________. This is catalysed by __________.
Acetyl-CoA transfers the acetyl group to oxaloacetate (4C), forming citrate (6C).
Enzyme: Citrate synthase
2nd step of TCA cycle:
Citrate (6C) then undergoes isomerisation to form ________. This is catalysed by _______.
Isocitrate;
catalysed by aconitase
3rd step of TCA:
Isocitrate (6C) then undergoes oxidative decarboxylation by (enzyme) to form _______.
___ and ___ are produced in the process.
Isocitrate undergoes OD to form a-ketogluterate (5C), catalysed by isocitrate dehydrogenase.
NADH and CO2 are produced.
4th step of TCA:
a-ketogluterate then undergoes oxidative decarboxylation to form ______.
This is catalysed by ______.
NADH and CO2 are produced.
forms succinyl-CoA (4C)
enzyme: a-ketogluterate dehydrogenase
5th step of TCA:
Succinyl-CoA then undergoes ________ phophorylation to form ______.
This is catalysed by ________.
___ is formed in the process.
Succinyl-CoA then undergoes substrate-level phophorylation to form succinate.
This is catalysed by succinyl-CoA synthetase.
GTP is formed in the process.
6th step of TCA:
Succinate (4C) can then undergo oxidation to form _____.
This is catalysed by __________.
Fumerate (4C)
This is catalysed by succinate dehydrogenase.
7th step of TCA:
Fumerate can then undergo _____ to form malate, catalysed by ______.
Reaction: Hydration;
Product: Malate (4C)
Enzyme: Fumerase
8th step of TCA:
Malate (4C) can then undergo ________ to form ______, completing the cycle.
Enzyme involved:?
Reaction: Oxidation
Product: Oxaloacetate
Enzyme: Malate dehydrogenase
Amino acids are first degraded by removing the ______, which is excreted as urea.
amino group
________ occurs when the amine group is transferred from one amino acid to a keto acid to form a new pair of amino acids and keto acids.
Transamination reaction
Transamination reactions occur in the _______.
liver
Alanine (AA) can undergo a transamination reaction with ______ to form pyruvate and ______.
This is catalysed by ________.
Alanine + a-ketogluterate –> Pyruvate + Glutamate
Enzyme: Alanine aminotransferase
_______ are needed to transport NADH produced in the cytosol during glycolysis to the mitochondria, where it will be used for oxidative phosphorylation.
Mitochondrial shuttles
The glycerol phosphate shuttle produces ____ ATP per NADH.
1.5
The glycerol phosphate shuttle involves (enzyme) in the cytosol and the mitochondria.
glycerol-3-phosphate dehydrogenase
In the glycerol phosphate shuttle,
Cytosolic glycerol-3-phosphate transfers electrons from NADH to _________.
Mitochondrial glycerol-3-phosphate dehydrogenase then transfers the electrons from glycerol-3-phosphate to _____.
NADH –> glycerol-3-phosphate –> FAD –> Coenzyme Q (ETC)
The malate-aspartate shuttle produces ___ ATP per NADH.
2.5
Metabolism includes ______ and ______.
Catabolism and anabolism
Catabolism involves the use of _____ as the electron carrier.
NADH
Anabolism involves the use of _____ as the electron carrier.
NADPH
NADPH and NADH binds to different enzymes due to the _______ present on the NADPH, changing its conformation.
phosphate group
_______ is the process of re-oxidising NADH and FADH2 generated in the earlier parts of metabolism to produce ATP.
Oxidative Phosphorylation
NADH and FADH2 donates their ____ to the solvent surrounding the enzyme complex, while their ____ join the electron transport chain.
donates protons to surrounding; electrons join ETC
There are three membrane complexes and 2 mobile carriers on the electron transport chain.
They are:
1) NADH dehydrogenase complex
2) Ubiquinone/coenzyme Q
3) Cytochrome b-c1 complex
4) cytochrome-c
5) Cytochrome oxidase
Each unit on the ETC has a (higher/lower) affinity for electrons than the previous unit, allowing for sequential electron flow.
higher affinity
Cytochrome oxidase receives __ electrons from cytochrome c in the final electron transfer step and passes them to _____ to produce water.
4 electrons; oxygen
Why is molecular oxygen an ideal terminal electron acceptor?
It has a high affinity for electrons and provides a driving force for oxidative phosphorylation.
NADH donates electrons to _____ (complex) whereas FADH2 donates electrons to ______ (complex).
NADH –> NADH dehydrogenase complex
FADH2 –> Succinate dehydrogenase
Positive E value –> more easily (reduced/oxidised)
reduced
Protons are pumped from the _________ to the _______, generating a steep H+ concentration gradient across the membrane.
Actively transported from the matrix into the intermembrane space
________ (metabolic poison) inhibits the transfer of electrons from iron-sulfur centres in NADH dehydrogenase complex to ubiquinone.
Rotenone
_______ (poison) is a competitive inhibitor for succinate dehydrogenase, as it is structurally similar to succinate.
Malonate
_______ and ____ binds to the Fe3+ of the haem group in the cytochrome oxidase complex with high affinity. Haem group therefore cannot receive any electrons from cyt-c.
Cyanide and azides
______ is an antibiotic which inhibits oxidative phosphorylation by binding to the stalk of ATP synthase and blocking proton flow through the enzyme.
Ogliomycin
________ transports protons across the inner mitochondrial membrane, uncoupling oxidative phosphorylation from ATP production.
This markedly increases the metabolic rate and body temperature.
Dinitrophenol
________ is responsible for the regulated uncoupling of oxidative phosphorylation in newborns and hibernating animals, to generate heat from the dissipation of the proton gradient.
Thermogenin (UCP-1)
ATP is the inhibitor of _______ (enzyme) in glycolysis. It is therefore the rate-limiting step of glycolysis.
Phosphofructokinase
Arsenite and mercury have high affinity for sulfhydryl groups in reduced lipoamide, thus inhibiting the _________.
pyruvate dehydrogenase complex (PDC)
