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- Also known as Respiration. - Comprises of these different
processes depending on type of organism:
I. Anaerobic Respiration II. Aerobic Respiration
Comprises of these stages: glycolysis: glucose 2 pyruvate + NADH fermentation: pyruvate lactic acid or ethanol cellular respiration:
Comprises of these stages: Oxidative decarboxylation of pyruvate Citric Acid cycle Oxidative phosphorylation/ Electron Transport
Chain(ETC)
STARCHY FOOD
α – AMYLASE ; MALTASES
Glycolysis in cytosol
Brief overview of catabolism of glucose to generate energy
Glucose converted to glu-6-PO4
Start of cycle
2[Pyruvate+ATP+NADH]
- Krebs Cycle
- E transport chain
Aerobic condition; in mitochondriaAnaerobic
condition
Lactic Acid fermentation in muscle.
Only in yeast/bacteria Anaerobic respiration or
Alcohol fermentation
Pyruvate enters as AcetylcoA
Glucose
Cycle : anaerobic
Show time..
1st stage of glucose metabolism → glycolysis An anaerobic process, yields 2 ATP
(additional energy source) Glucose will be metabolized via gycolysis;
pyruvate as the end product The pyruvate will be converted to lactic acid
(muscles → liver) Aerobic conditions: the main purpose is to
feed pyruvate into TCA cycle for further rise of ATP
Fig. 17-1, p.464
The breakdown of glucose to pyruvate as summarized:
Glucose (six C atoms) → 2 pyruvate (three C atoms)2 ATP + 4 ADP + 2 Pi → 2 ADP + 4 ATP (phosphorylation)Glucose + 2 ADP + 2 Pi → 2 Pyruvate + 2 ATP (Net reaction)
Fig. 17-2, p.465
Louis Pasteur- French biologist- did research on fermentation which led to important discoveries in microbiology and chemistry
p.467
Step 1 Glucose is phosphorylated to give gluc-6-phosphatePreparation phase
Fig. 17-3, p.468
Table 17-1, p.469
Fig. 17-4, p.470
p.470a
Step 2 Glucose-6-phosphate isomerize to give fructose-6-phosphate
p.470b
Step 3 Fructose-6-phosphate is phosphorylated producing fructose-1,6-bisphosphate
Fig. 17-6, p.471
p.471a
Step 4 Fructose-1,6-bisphosphate split into two 3-carbon fragments
p.471b
Step 5 Dihydroxyacetone phosphate is converted to glyceraldehyde-3-phosphate
p.472
Step 6
Payoff phase
Glyceraldehyde-6-phosphate is oxidized to 1,3-bisphosphoglycerate
Fig. 17-7, p.473
p.474a
Fig. 17-8, p.475
p.476
Step 7 Production of ATP by phosphorylation of ADP
p.477a
Step 8 Phosphate group is transferred from C-3 to C-2
p.477b
Step 9 Dehydration reaction of 2-phosphoglycerate to phosphoenolpyruvate
p.478
Step 10 Phosphoenolpyruvate transfers its phosphate group to ADP → ATP and pyruvate
Fig. 17-10, p.479
Control points in glycolysis
p.479
Conversion of pyruvate to lactate in muscle
Fig. 17-11b, p.481
Fig. 17-11a, p.481
Pyruvate decarboxylase
Fig. 17-12, p.482
p.482
Acetaldehyde + NADH → Ethanol + NAD+
Glucose + 2 ADP + 2 Pi + 2 H+ → 2 Ethanol + 2 ATP + 2 CO2 + 2 H2O
Carbohydrate metabolism
Gluconeogenesis
Conversion of pyruvate to glucose Biosynthesis and the degradation of many important
biomolecules follow different pathways There are three irreversible steps in glycolysis and the
differences bet. glycolysis and gluconeogenesis are found in these reactions
Different pathway, reactions and enzyme
p.495
STEP 1
is the biosynthesis of new glucose from non-CHO precursors.
this glucose is as a fuel source by the brain, testes, erythrocytes and kidney medulla
comprises of 9 steps and occurs in liver and kidney the process occurs when quantity of glycogen have been
depleted - Used to maintain blood glucose levels. Designed to make sure blood glucose levels are high
enough to meet the demands of brain and muscle (cannot do gluconeogenesis).
promotes by low blood glucose level and high ATP inhibits by low ATP occurs when [glu] is low or during periods of fasting/
starvation, or intense exercise pathway is highly endergonic *endergonic is energy consuming
STEP 2
The oxalocetate formed in the mitochondria have two fates:
- continue to form PEP- turned into malate by malate dehydrogenase and leave the mitochondria, have a reaction reverse by cytosolic malate dehydrogenase
Reason?
Fig. 18-12, p.502
Controlling glucose metabolism• found in Cori cycle• shows the cycling of glucose due to gycolysis in muscle and gluconeogenesis in liver
As energy store for next exercise
• This two metabolic pathways are not active simultaneously.• when the cell needs ATP, glycolisys is more active•When there is little need for ATP, gluconeogenesis is more active
Cori cycle requires the net hydrolysis of two ATP and two GTP.
OHATPHNADHPyruvate
PADPNADeglu i
222422
222cos
iPGDPADPNADeGlu
OHGTPATPHNADHPyruvate
6242cos
624422 2
iPGDPADP
OHGTPATP
422
422 2
Fig. 18-13, p.503
The Citric Acid cycle
Cycle where 30 to 32 molecules of ATP can be produced from glucose in complete aerobic oxidation
Amphibolic – play roles in both catabolism and anabolismThe other name of citric acid cycle: Krebs cycle and
tricarboxylic acid cycle (TCA)Takes place in mitochondria
Fig. 19-2, p.513
Fig. 19-3b, p.514
Steps 3,4,6 and 8 – oxidation reactions
5 enzymes make up the pyruvate dehydrogenase complex: pyruvate dehydrogenase (PDH) Dihydrolipoyl transacetylase Dihydrolipoyl dehydrogenase Pyruvate dehydrogenase kinase Pyruvate dehydrogenase phosphatase
Conversion of pyruvate to acetyl-CoA
p.518
Step 1 Formation of citrate
Table 19-1, p.518
Step 2 Isomerization
Fig. 19-6, p.519
cis-Aconitate as an intermediate in the conversion of citrate to isocitrate
Fig. 19-7, p.521
Step 3
Formation of α-ketoglutarate and CO2 – first oxidation
p.521
Step 4 Formation of succinyl-CoA and CO2 – 2nd oxidation
p.522
Step 5 Formation of succinate
p.523a
Step 6
Formation of fumarate – FAD-linked oxidation
p.524a
Step 7 Formation of L-malate
p.524b
Step 8 Regeneration of oxaloacetate – final oxidation step
Fig. 19-8, p.526
Krebs cycle produced:• 6 CO2
• 2 ATP• 6 NADH• 2 FADH2
Table 19-3, p.527
Fig. 19-10, p.530
Fig. 19-11, p.531
Fig. 19-12, p.533
Fig. 19-15, p.535
Overall production from glycolysis, oxidative decarboxylation and TCA:
Oxidative decarboxylatio
n
Glycolysis TCA cycle
- 2 ATP 2 ATP
2 NADH 2 NADH 6 NADH , 2 FADH2
2 CO2 2 Pyruvate 4 CO2
Electron transportation system