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Flashcards in Metabolism Deck (98):
1

Autotrophs

organisms that obtain their carbon from in an inorganic form (such as CO2)

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Photosynthesis

using solar energy to convert inorganic carbon into organic carbon

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Chemosynthesis

Using chemical energy to convert inorganic carbon into organic carbon

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Heterotrophs

Organisms that take in carbon already in an organic form from other organisms

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Metabolism

All enzyme catalyzed reactions in a cell

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Catabolism

Degrading reactions, typically release energy

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Anabolism

Building reactions, typically requires energy

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ATP

Adenosine Triphosphate, an energy carrier or transmitter, not an energy store. A nucleoside triphosphate with Adenine as the nucleoside base.

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Nucleoside triphosphate

A class of molecule to which ATP belongs. A nucleoside base, attached to a ribose molecule bonded to a chain of three phosphate molecules. The bonds between phosphate molecules have lots of energy.

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ADP

Adenosine Diphosphate

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Energy released in going from ATP to ADP

30.5Kj

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phosphorylation

A reaction where phosphate is added to something, for example to ADP to make ATP

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Substrate level Phosphorylation

Phosphate moves from one substrate to another

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NAD+ and FAD

nicotinamide adenine dinucleotide and Flavin adenine dinucleotide respectively, they act as electron acceptors

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Aerobic Respiration

Fuel is completely oxidized to CO2 and ATP is generated through both substrate level Phosphorylation and oxidative phosphorylation

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What form of NAD+ and FAD is oxidized

NAD+ and FAD

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what form of NAD+ and FAD is reduced

NADH and FADH2

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Glycolysis

the first stage of ATP generation of any kind in which glucose is converted through a 10 step process to pyruvate

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1st step of glycolysis

glucose is phosphorylated to glucose-6-phosphate, consuming 1 ATP

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2nd step of glycolysis

glucose-6-phosphate is isomerised to fructose-6-phosphate

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3rd step of glycolysis

fructose-6-phosphate is phosphorylated to fructose-1,6-bisphosphate, this consumes 1 ATP

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4th step of glycolysis

fructose-1,6-bisphosphate is cleaved to produce dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P)

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DHAP

dihydroxyacetone phosphate

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G3P

glyceraldehyde-3-phosphate

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5th step of glycolysis

DHAP is isomerised to G3P, there are now two G3P molecules that proceed through the reaction

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6th step of glycolysis

G3P is oxidized to 1,3-bisphosphoglycerate, this reduces one NAD+ and consumes one phosphate

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7th step of glycolysis

1,3-bisphosphoglycerate is dephosphorylated to 3-phosphoglycerate generating 1 ATP

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8th step of glycolysis

3-phosphoglycerate is converted to 2-phosphoglycerate

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9th step of glycolysis

2-phosphoglycerate is converted to phosphoenolpyruvate

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10th step of glycolysis

phosphoenolpyruvate is dephosphorylated to pyruvate generating 1 ATP

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Overall reaction of glycolysis

glucose + 2ADP + 2Pi + 2NAD+ -> 2pyruvate + 2ATP + 2NADH

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Fermentation

A process of breaking down pyruvate that serves to oxidize NADH such that the cell does not run out of NAD+ required for glycolysis

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where does ethanol fermentation occur

The cytoplasm of yeast cells

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what is the process of ethanol fermentation

pyruvate gives off CO2 making acetaldehyde which further converts to ethanol. NADH is oxidized in the process

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what is the overall reaction of ethanol fermentation and glycolysis

glucose + 2ADP + 2Pi -> 2ethanol + 2CO2 +2ATP

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where does lactic acid fermentation occur

in the cytoplasm of muscle cells and microbes

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what is the process of lactic acid fermentation

pyruvate converts to lactate and NADH is oxidized

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what is the overall reaction of lactic acid fermentation and glycolysis

glucose + 2ADP + 2Pi -> 2lactate + 2ATP

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TCA Cycle

The section of ATP generation after glycolysis where pyruvate is oxidized to CO2. Also called the krebs cycle or the citric acid cycle

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TCA Cycle

The section of ATP generation after glycolysis where pyruvate is oxidized to CO2. Also called the krebs cycle or the citric acid cycle

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CoA

Co-enzyme A, an enzyme that activates pyruvate allowing it to enter into the mitochondria and the TCA Cycle

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TCA

tricarboxylic acid

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Step 1 of the TCA Cycle

Pyruvate (3C) is decarboxylated to acetyl CoA (2C) realising 1 CO2 and producing 1 NADH

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Step 2 of the TCA Cycle

Acetyl CoA (2C) is combined with oxaloacetate (4C) to produce citrate (6C)

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Step 3 of the TCA Cycle

Citrate (6C) is isomerised to isocitrate (6C)

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Step 4 of the TCA Cycle

Isocitrate (6C) is oxidized to alpha-ketoglutarate (5C) producing 1CO2 and 1NADH

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Step 5 of the TCA Cycle

alpha-ketoglutarate (5C) is oxidized to succinyl CoA (4C) producing 1CO2 and 1NADH, at this stage the pyruvate has been completely oxidized

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Step 6 of the TCA Cycle

Succinyl CoA is converted to Succinate producing 1GTP through substrate level Phosphorylation

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GTP

Guanosine triphosphate, basically just ATP

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Step 7 of the TCA Cycle

Succinate is oxidized to fumerate, producing 1 FADH2

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Step 8 of the TCA Cycle

fumarate is converted to malate

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Step 9 of the TCA Cycle

malate is oxidized to oxaloacetate, producing 1 NADH. Oxaloacetate then goes to step 2.

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Glycerol Phosphate shuttle

In the presence of oxygen NADH from glycolysis is oxidized alongside dihydroxyacetone phosphate reducing to 2-glycerol-3-phosphate. 2-glycerol-3-phosphate can travel into the mitochondria and oxidized back to dihydroxyacetone phosphate allowing FAD to oxidize to FADH2. The dihydroxyacetone phosphate then leaves the mitochondria and continues through glycolysis.

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How many moles of ATP are produced from 1 mol of glucose

36, 2 from glucose, 30 from TCA/ETC and 4 from the G3P shuttle

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The overall reaction of ATP generation

glucose + 6O2 + 36ADP + 36Pi -> 6CO2 +6H2O + 36ATP

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How much energy is released from glucose, trapped in ATP and what is the efficiency

2870Kj released, 1098Kj trapped. efficiency is 38%

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Electron Transport Chain

A series of redox reactions resulting in the reduction of O2 to H2O that serves to re-oxidise electron acceptors and generate ATP

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Cytochrome

general name for proteins that contain iron ions that van be either oxidized (Fe3+) or reduced (Fe2+)

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what is the sequence of chemicals in the electron transport chain

NADH -> NADH oxidoreductase -> coenzyme q -> cytochrome b -> cytochrome c1 -> cytochrome c -> cytochrome (a+a3) -> O2 to H20

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at what step does FADH2 enter the chain

FADH2 passes it's electron to coenzyme q

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How much ATP is released from NADH and FADH2

3 ATP from NADH and 2 ATP from FADH2

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Why does NADH not just immediately react to H20

Thos would be less efficient as the energy released would only have the potential to be captured by one ATP instead of 3

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Where does oxidative Phosphorylation/ETC occur

in the intermembrane space of the mitochondria/in the inner membrane of the mitochondria

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Respiratory Control

regulation of oxidative Phosphorylation by ADP levels, preventing the coupled process of ETC occurring hence preventing he unnecessary catabolism of fuel

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Chemiosmotic theory

Energy released during the ETC forve H+ ions across the inner mitochondrial membrane into the intermembrane space, the resulting electrochemical gradient causes H+ ions to flow back across the membrane through ATP synthase, the gradient's energy is hence used by ATP synthase to synthesize ATP

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ATP Synthase

a protein imbeded in the inner mitochondrial membrane that is used to synthesize ATP in line with the chemiosmotic theory

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What reaction does ATP synthase make use of

ATP + H2O ADP + Pi + H+

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Translocase proteins

proteins that allow ADP and Pi to enter the mitochondria and ATP to exit the mitochondria

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2,4-dinitrophenol

a chemical that uncouples ETC and oxidative phosphorylation by shuttling protons across membranes

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How are other saccharides metabolized

They are cleaved into monosaccharides (in the digestive track/inside bacteria/by enzymes excreted by bacteria) and then reactes into a chemical used in glycolysis, resulting in the same ATP output as glucose

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amylase

an enzyme that breaks down starch and glycogen

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cellulase

an enzyme that breaks down cellulose

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How are triglycerides metabolized

glycerol proceds through glycolysis (with a net gain of 1 ATP) and the fatty acid chains are split into acetyl CoA and procced through the TCA Cycle

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how are proteins metabolized

the a NH2 groups of amino acids are removed through deamination and the the left over bits are fed into the TCA Cycle

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Gluconeogenesis

synthesis of glucose from non-carbohydrate precursors mostly occuring in the liver and kidneys

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Where do precursors feed in to gluconeogenesis

lactate and some amino acids are converted to pyruvate, other amino acids are converted straight to oxaloacetate

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pyruvate kinase

enzyme associated with the reaction of phosphoenolpyruvate to pyruvate

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phosphofructokinase

enzyme associated with the reaction of fructose-6-phosphate to fructose-1,6-bisphosphate

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hexokinase

enzyme associated with the reaction of glucose to glucose-6-phosphate

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4 essential enzymes for gluconeogenesis and their location

pyruvate carboxylase (mitochondria), phosphoenolpyruvate carboxykinase (cytoplasm), fructose-1,6-bisphosphatase (cytoplasm), glucose-6-phosphatase (endoplasmic reticulum)

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step 1 of gluconeogenesis

pyruvate is carboxylated to oxaloacetate in the mitochondria requiring one ATP and using pyruvate carboxylase

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step 2 of gluconeogenesis

oxaloacetate is temporarily converted to malate so it can leave the mitochondria before being oxidized back, NAD+ is used as an electron acceptor

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step 3 of gluconeogenesis

oxaloacetate is decarboxylated and phosphorylated to phosphoenolpyruvate requiring one GTP and using phosphoenolpyruvate carboxykinase

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step 4 of gluconeogenesis

phosphoenolpyruvate is converted to 2-phosphoglycerate

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step 5 of gluconeogenesis

2-phosphoglycerate is converted to 3-phosphoglycerate

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step 6 of gluconeogenesis

3-phosphoglycerate is phosphorylated to 1,3-bisphosphoglycerate requiring 1 ATP

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step 7 of gluconeogenesis

1,3-bisphosphoglycerate is reduced and dephosphorylated to glyceraldehyde-3-phosphate, oxidizing one NADH to NAD+

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step 8 of gluconeogenesis

half the G3P is converted to DHAP

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step 9 of gluconeogenesis

one G3P and DHAP are combined to make fructose-1,6-bisphosphate

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step 10 of gluconeogenesis

fructose-1,6-bisphosphate is dephosphorylated to fructose-6-phosphate using phosphofructokinase

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step 11 of gluconeogenesis

fructose-6-6-phosphate is isomerised to glucose -6-phosphate

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step 12 of gluconeogenesis

glucose-6-phosphate is dephosphorylated to glucose using hexokinase

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Overall formula for gluconeogenesis

2pyruvate + 4ATP + 2GTP + 2NADH -> glucose + 4ADP + 2GDP +6Pi + 2NAD+

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Photosynthesis

A series of reactions converting CO2 to organic sugars using solar energy

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where does photosynthesis occur

chloroplasts, a type of plastid

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what are the two phases photosynthesis

energy transduction (converting light to chemical energy-light dependent) carbon assimilation (carbon is converted to organic sugars-light independent)

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describe energy transduction

light passes through leaves, hitting the thylakoid where membrane bound proteins use light to oxidize water creating an energy gradient with protons going from the stroma to the thylakoid lumen. the ETC makes NADPH and ATP synthase makes ATP

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equation for carbon assimilation

6CO2 + 12H2O -> C6H12O6 + 6H20 + 6O3 this uses ATP and NADPH