Energy III: Krebs Cycle And Electron Transport Chain
¬¬¬Biology Exam 4
Energy III – Cellular Respiration (Krebs Cycle and Electron Transport Chain)
A. The Krebs Cycle
a. Energy
i. The net gain of 2 ATP and 2 NADH represents an effective transfer of 20 kcal of energy to ATP (about 10 kcal each) about 80 kcal of energy to NADH (about 40 kcal each), for a total of about 100 kcal ii. Complete oxidation of glucose results in the release of 684 kcal of energy, significant energy still remaining in pyruvate
b. Eukaryotes
i. Pyruvate is transported across mitochondrial membrane, then converted t acetyl CoA (with production of NADH and carbon dioxide)
c. Acetyl CoA
i. Is oxidized by a series of enzymes which make up cyclical series of reactions (Krebs Cycle)
d. Krebs Cycle
i. Electrons …show more content…
This tutorial focused on the final steps of cellular respiration; the Krebs cycle and the Electron Transport Chain and chemiosmosis. Recall that at the end of glycolysis there is a net production of two molecules of ATP and two molecules of NADH. The ATP is produced via substrate-level phosphorylation; in this reaction, a phosphate group on an organic molecule is transferred directly (along with high-energy electrons) onto a molecule of ADP. Substrate-level phosphorylation also occurs once during the Krebs cycle.For those organisms that completely oxidize glucose, the end product of glycolysis (pyruvate) is further oxidized by enzymes associated with the Krebs cycle (also known as the citric acid cycle and the tricarboxylic acid cycle or TCA cycle). In eukaryotes, the enzymes associated with the Krebs cycle are found in the mitochondria. Pyruvate moves into the mitochondria via specific carrier proteins located in the mitochondrial membranes (in prokaryotes, the Krebs cycle enzymes typically are not compartmentalized but are located in the same compartment as the glycolytic enzymes). Pyruvate is converted to acetyl CoA (accompanied by the evolution of CO2 and one molecule of NADH). The acetyl CoA then enters the Krebs cycle. Within the cell, the Krebs cycle organic acids are not arranged in a circle nor is there any circular arrangement of the enzymes. This pathway is termed a "cycle" (and diagrammed as a circle) because the end product becomes the first product after …show more content…
Then splits and forms 2 3-carbon molecules
b. Rubisco
i. Most abundant molecule on earth ii. Catalyzes reaction above
c. Carbon dioxide in Calvin cycle
i. Gets into chloroplast – many ways ii. Algae – diffuses through membranes from surrounding water iii. Plants – carbon dioxide comes through stoma (pores) in leaves
1. These pores is where oxygen escapes into atmosphere (produced in the light reactions)
E. Reduction of the two, 3 –carbon compounds
a. Phase 1 of Calvin cycle
i. Carbon dioxide is fixed into 6-carbon molecule – splits into 2 3-carbon molecule
b. Phase 2 of Calvin cycle
i. 3-carbon molecules are reduced to glyceraldehyde 3-phosphate (G3P) [3 carbon molecule] ii. NADPH is produced by light-dependent reactions – high energy electrons for this process iii. ATP – used in anabolic reactions
c. Calvin Cycle
i. Energetically tied to light-dependent reactions of photosynthesis ii. End of reduction phase iii. Some G3P leaves cycle – sugar iv. Mostly used to regenerate RuBP
d. G3P
i. GLUCOSE NOT MADE – G3P (sugar) is ii. G3P used by cell – energy source/build glucose molecules used by plants to build cell walls, starches, and other polysaccharides
F. Regeneration of G3P to RuBP
a. Krebs/Calvin
Energy III – Cellular Respiration (Krebs Cycle and Electron Transport Chain)
A. The Krebs Cycle
a. Energy
i. The net gain of 2 ATP and 2 NADH represents an effective transfer of 20 kcal of energy to ATP (about 10 kcal each) about 80 kcal of energy to NADH (about 40 kcal each), for a total of about 100 kcal ii. Complete oxidation of glucose results in the release of 684 kcal of energy, significant energy still remaining in pyruvate
b. Eukaryotes
i. Pyruvate is transported across mitochondrial membrane, then converted t acetyl CoA (with production of NADH and carbon dioxide)
c. Acetyl CoA
i. Is oxidized by a series of enzymes which make up cyclical series of reactions (Krebs Cycle)
d. Krebs Cycle
i. Electrons …show more content…
This tutorial focused on the final steps of cellular respiration; the Krebs cycle and the Electron Transport Chain and chemiosmosis. Recall that at the end of glycolysis there is a net production of two molecules of ATP and two molecules of NADH. The ATP is produced via substrate-level phosphorylation; in this reaction, a phosphate group on an organic molecule is transferred directly (along with high-energy electrons) onto a molecule of ADP. Substrate-level phosphorylation also occurs once during the Krebs cycle.For those organisms that completely oxidize glucose, the end product of glycolysis (pyruvate) is further oxidized by enzymes associated with the Krebs cycle (also known as the citric acid cycle and the tricarboxylic acid cycle or TCA cycle). In eukaryotes, the enzymes associated with the Krebs cycle are found in the mitochondria. Pyruvate moves into the mitochondria via specific carrier proteins located in the mitochondrial membranes (in prokaryotes, the Krebs cycle enzymes typically are not compartmentalized but are located in the same compartment as the glycolytic enzymes). Pyruvate is converted to acetyl CoA (accompanied by the evolution of CO2 and one molecule of NADH). The acetyl CoA then enters the Krebs cycle. Within the cell, the Krebs cycle organic acids are not arranged in a circle nor is there any circular arrangement of the enzymes. This pathway is termed a "cycle" (and diagrammed as a circle) because the end product becomes the first product after …show more content…
Then splits and forms 2 3-carbon molecules
b. Rubisco
i. Most abundant molecule on earth ii. Catalyzes reaction above
c. Carbon dioxide in Calvin cycle
i. Gets into chloroplast – many ways ii. Algae – diffuses through membranes from surrounding water iii. Plants – carbon dioxide comes through stoma (pores) in leaves
1. These pores is where oxygen escapes into atmosphere (produced in the light reactions)
E. Reduction of the two, 3 –carbon compounds
a. Phase 1 of Calvin cycle
i. Carbon dioxide is fixed into 6-carbon molecule – splits into 2 3-carbon molecule
b. Phase 2 of Calvin cycle
i. 3-carbon molecules are reduced to glyceraldehyde 3-phosphate (G3P) [3 carbon molecule] ii. NADPH is produced by light-dependent reactions – high energy electrons for this process iii. ATP – used in anabolic reactions
c. Calvin Cycle
i. Energetically tied to light-dependent reactions of photosynthesis ii. End of reduction phase iii. Some G3P leaves cycle – sugar iv. Mostly used to regenerate RuBP
d. G3P
i. GLUCOSE NOT MADE – G3P (sugar) is ii. G3P used by cell – energy source/build glucose molecules used by plants to build cell walls, starches, and other polysaccharides
F. Regeneration of G3P to RuBP
a. Krebs/Calvin