Term
| Why do we need to breath? |
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Definition
to make water
2 H2 + O2 → 2 H2O + energy |
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Term
| What is cellular respiration? |
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Definition
| Making water, the productive way |
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Term
| What are the three parts of cellular respiration? |
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Definition
Glycolysis
Citric Acid Cycle
Oxidative phosphorylation |
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Term
| What are the two parts of glycolysis? |
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Definition
Energy investment
Energy Payoff |
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Term
| What does the citric acid cycle require before the cycle? |
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Definition
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Term
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Definition
◦ Glucose is oxidized to pyruvate
NADH and ATP are formed
sugar splitting
◦ Two phases:
Energy investment
IN: Glucose, 2ATP
OUT: 2G3P
Energy payoff
IN: 2G3P
OUT: 4 ATP, 2 NADH,
2 Pyruvate
◦ Ten enzyme-mediate steps
◦ All intermediates are phosphorylated |
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Term
| What is the citric acid cycle? |
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Definition
◦ Pyruvate derivative is oxidized to CO2
NAD, FADH2 and ATP are formed |
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Term
| What is the oxidative phosphorylation? |
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Definition
◦ Electron transport chain creates proton gradient
Gradient used to form ATP |
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Term
| What comes in and out of energy investment? |
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Definition
Energy investment
IN: Glucose, 2ATP
OUT: 2G3P |
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Term
| What comes in and out of energy payoff? |
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Definition
Energy payoff
IN: 2G3P
OUT: 4 ATP, 2 NADH,
2 Pyruvate |
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Term
| What enzymes are used in glycolysis? |
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Definition
Kinase
Isomerase
Dehydrogenase |
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Term
| Describe energy investment |
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Definition
Step 1
The step one in glycolysis is phosphorylation. This step glucose is phosphorylated by the enzyme hexokinases. In this process, ATP molecule is consumed. A phosphate group from the ATP is transferred to the glucose molecules to produce glucose-6-phosphate.
Glucose (C6H12O6) + Hexokinase + ATP → Glucose-6-phosphate (C6H11O6P1) + ADP
Step 2
The second stage of glycolysis is an isomerization reaction. In this reaction the glucose-6-phosphate is rearranged into fructose-6-phosphate by the enzyme glucose phosphate isomerase. This is a reversible reaction under normal conditions of the cell.
Glucose-6-phosphate (C6H11O6P1) + Phosphoglucoisomerase → Fructose-6-phosphate (C6H11O6P1)
Step 3
In the third step of glycolysis is a phosphorylation reaction. In this step the enzyme phosphofructokinase is transfers phosphate group to form fructose 1,6-bisphosphate. Another ATP molecule is used in this step.
Fructose 6-phosphate (C6H11O6P1) + phosphofructokinase + ATP → Fructose 1,6-bisphosphate (C6H10O6P2) + ADP
Step 4
This step in glycolysis is a destabilization step, where a the action of the enzyme aldolase splits fructose 1,6-bisphosphate into two sugars. These sugars are isomers of each other, they are dihydroxyacetone phosphate and glyceraldehyde phosphate.
Fructose 1,6-bisphosphate (C6H10O6P2) + aldolase → Dihydroxyacetone phosphate (C3H5O3P1) + Glyceraldehyde phosphate (C3H5O3P1)
Step 5 of glycolysis is an interconversion reaction. Here, the enzyme triose phosphate isomerase interconverts the the molecules dihydroxyacetone phosphate and glyceraldehyde phosphate.
Dihydroxyacetone phosphate (C3H5O3P1) → Glyceraldehyde phosphate (C3H5O3P1)
This step marks the end of the preparatory or the investment phase of glycolysis. So at the end here, the 6-carbon glucose molecule is split into two three-carbon molecules with the expense of two ATP molecules. |
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Term
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Definition
The second phase of glycolysis is known as the pay-off phase of glycolysis. This phase is characterized by gain of the energy-rich molecules ATP and NADH.
Step 6
This step of glycolysis is a dehydrogenation step. The enzyme triose phosphate dehydrogenase, dehydrogenates glyceraldehyde 3-phosphate and adds an inorganic phosphate to form 1,3-bisphosphoglycerate. Firstly, the enzyme action transfers a H- (hydrogen) from glyceraldehyde phosphate to the NAD+ which is an oxidizing agent to form NADH. The enzyme also adds a inorganic phosphate from the cytosol to the glyceraldehyde phosphate to form 1,3-bisphosphoglycerate. This reaction occurs with both the molecules produced in the previous step.
2 Glyceraldehyde phosphate (C3H5O3P1) + Triose phosphate dehydrogenase + 2H- + 2P + 2NAD+ → two 1,3-bisphosphoglycerate
(C3H4O4P2) + 2NADH + 2H+
Step 7
Step 7 of glycolysis is a substrate-level phosphorylation step, where the enzyme phosphoglycerokinase transfers a phosphate group from 1,3-bisphosphoglycerate. The phosphate is transferred to ADP to form ATP. This process yields two molecules of 3-phosphoglycerate molecules and two molecules of ATP. There are two moleculesof ATP synthesized in this step of glycolysis.
2 molecules of 1,3 bisphophoglycerate (C3H4O4P2)+ phosphoglycerokinase + 2 ADP → 2 molecules of 3-phosphoglycerate (C3H5O4P1) + 2 ATP
Step 8
This step of glycolysis is a mutase step, occurs in the presence of the enzyme phosphoglycerate mutase. This enzyme relocates the phosphate from the 3-phosphoglycerate molecule ar third carbon position to the second carbon position, this results in the formation of 2-phosphoglycerates.
2 molecules of 3-phsophoglycerate (C3H5O4P1) + phsosphoglyceromutase → 2 molecules of 2-Phosphoglycerate (C3H5O4P1)
Step 9
This step of glycolysis is a lyase reaction, which occurs in the presence of enolase enzyme. In this reaction the enzyme removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP)
2 molecules of 2-phosphoglycerate (C3H5O4P1) + enolase → 2 molecules of phosphoenolpyruvic acid (PEP) (C3H3O3P1) + H2O
Step 10
This is the final stage of glycolysis which is a substrate-level phsophorylation step. In the presence of the enzyme pyruvate kinase, there is transfer of a inorganic phosphate molecule from phosphoenol pyruvate molecule to ADP to form pyruvic acid and ATP. This reaction yields 2 molecules of pyruvic acid and two molecules of ATP.
2 molecules of PEP (C3H3O3P1) + pyruvate kinase + 2 ADP → 2 molecules of pyruvic acid (C3H4O3) + 2 ATP
This reaction marks the end of glycolysis, hereby producing two ATP molecules per glucose molecule. |
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Term
| What is substrate level phosphorylation? |
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Definition
◦ Phosphate transferred directly from substrate to
ADP to form ATP |
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Term
| What is pyruvate oxidation? |
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Definition
◦ Pyruvate is imported into mitochondria and oxidized,
forming Acetyl CoA
NADH and CO2 are produced |
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Term
| Describe the steps of pyruvate oxidation |
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Definition
◦ Step 1 – transfer pyruvate into mitochondria
Facilitated diffusion across outer membrane
Active transport into matrix – pyruvate translocase
-OH antiporter, using energy in proton gradient
◦ Several linked enzymatic reactions
Stripping CO2
Attachment of remaining Acetate to
Coenzyme A
Transfer of electrons to NADH |
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Term
| What come in and out of pyruvate oxidation? |
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Definition
IN: Pyruvate (cytoplasm)
OUT: Acetyl-CoA (matrix),
CO2
, NADH
(reduction of gradient by 1 H+)
(everything x2 if starting from 1
glucose) |
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Term
| What occurs during the citric acid cycle? |
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Definition
◦ Acetyl CoA is added to Oxaloacetate, then oxidized,
producing CO2
NADH, FADH2 and ATP are formed |
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Term
| How was the citric acid cycle characterized and why is it cyclical? |
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Definition
Citric acid cycle
◦ Characterized by Hans Krebs
formerly called Krebs cycle
◦ Cyclical
First step produces citric acid
Begins and ends with
oxaloacetate |
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Term
| What comes in and out of the citric acid cycle? |
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Definition
IN: Acetyl CoA
OUT: 3 NADH, 1 FADH2
1 GTP (or ATP),
2 CO2
(everything x2 if
starting from glucose) |
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