Topic 8.2: Cell Respiration

Essential Idea:  Energy is converted to a usable form in cell respiration.

At SHS, Topic 8.2 is taught in the following class unit(s):

• Anaerobic Respiration (unit 33A)
• Aerobic Respiration (unit 33B)

Statements & Objectives:

8.2.U1  Cell respiration involves the oxidation and reduction of electron carriers.

• Outline oxidation and reduction reactions in terms of movement of electrons, hydrogen or oxygen atoms.
• Define “electron carrier.”
• State the name of the electron carrier molecule used in cellular respiration.​​

8.2.U2  Phosphorylation of molecules makes them less stable.

• Define phosphorylation.
• State the consequence of a molecule being phosphorylated.​

8.2.U3  In glycolysis, glucose is converted to pyruvate in the cytoplasm.

• Outline the glycolysis reaction, including phosphorylation, lysis and energy harvest.​

8.2.U4  Glycolysis gives a small net gain of ATP without the use of oxygen.

• State the formula for the glycolysis reaction.
• State that glycolysis occurs in both anaerobic and aerobic respiration.
• State that glycolysis is an example of a metabolic pathway.

8.2.U5  In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.

• Define decarboxylation and oxidation.
• ​Summarize the reactant and products of the link reaction.

8.2.U6  In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers, liberating carbon dioxide.

• State that NADH and FADH2 are electron carriers formed during the Krebs cycle.
• Outline the events of the Krebs cycle, referencing the formation of NADH and FADH2, formation of ATP and decarboxylation of acetyl groups.

8.2.U7  Energy released by oxidation reactions is carried to the cristae of the mitochondria by reduced NAD and FAD.

• State that NAD+ is reduced to become NADH in the link reaction and Krebs cycle.
• State that FAD is reduced to become FADH2 in the Krebs cycle.
• State that NADH and FADH2 carry electrons to the electron transport chain on the mitochondrial inner membrane. ​

8.2.U8  Transfer of the electrons between carriers in the electron transport chain in the membrane of the cristae is coupled to proton pumping.

• State that at the electron transport chain, FADH2 and NADH given electrons to electron carrier proteins.
• State that the movement of electrons through electron carrier proteins in the electron transport chain is used to pump protons (H+) across the inner mitochondrial membrane into the intermembrane space.​

8.2.U9  In chemiosmosis protons diffuse through ATP synthase to generate ATP.

• Define oxidative phosphorylation and chemiosmosis.​

8.2.U10  Oxygen is needed to bind with the free protons to maintain the hydrogen gradient, resulting in the formation of water.

• ​State that oxygen is the final electron acceptor in aerobic cellular respiration.
• State that that formation of water in the matrix at the end of the electron transport chain helps to maintain the hydrogen gradient between the intermembrane space and the matrix.

8.2.U11  The structure of the mitochondrion is adapted to the function it performs.

• Outline how mitochondria structure could evolve through natural selection.
• State evidence that suggests mitochondria were once free living prokaryotes.

8.2.A1  Electron tomography used to produce images of active mitochondria.

• State that electron tomography enables scientists to view the dynamic nature of mitochondrial membranes. ​

8.2.S1  Analysis of diagrams of the pathways of aerobic respiration to decide where decarboxylation and oxidation reactions occur.

• State that decarboxylation of glucose occurs in the linking reaction and Krebs cycle of aerobic respiration.

8.2.S2  Annotations of a diagram of mitochondrion to indicate the adaptations to its function.

• ​Draw and label a diagram of the mitochondria.
• State the function of the following mitochondrial structures:  outer membrane, inner membrane, cristae, intermembrane space, matrix, ribosome and mtDNA.

8.2.NOS  Paradigm shift-chemiosmotic theory led to a paradigm shift in the field of bioenergetics.

• State that Peter Mitchell’s proposal of the chemiosmotic hypothesis in 1961 lead to a major shift in our understanding of cellular processes. ​

In the News:

• Mistletoe is missing the machinery to make energy (2018-05-03)
• Solving the structure of ATP synthase (2018-04-17)
• Scientists illuminate mysterious molecular mechanism powering cells in most forms of life (2015-01-08)