Chapter 7 Cellular Respiration and Fermentation

Explain the difference between fermentation and cellular respiration.

Fermentation is the partial degradation of sugars or other organic fuel without oxygen while cellular respiration uses oxygen.

Write the summary equation for cellular (aerobic) respiration. Write the specific chemical equation for the degradation of glucose.

C₆H₁₂O₆ + 6 O₂  —> 6 CO₂ + 6 H₂O + Energy
Organic compounds + oxygen —> carbon dioxide + water + energy

Define Oxidation (OIL)

Oxidation is the loss of an electron

Oxidation Is Loss

Describe the role of NAD+ in cellular respiration

It acts as an electron carrier and its where hydrogens are held in the cell temporarily.

In general terms, explain the role of the electron transport chain in cellular respiration

NADPH passes electrons to the electron transport chain, from which they eventually combine with hydrogen ions and oxygen to form water.

Name the three stages of cellular respiration and state the region of the eukaryotic cell where each stage occurs.

Glycolysis, citric acid cycle, oxidative phosphorylation

Glycolysis is located in the cytosol, citric acid cycle and oxidative phosphorylation is located in the mitochondrial matrix.

Describe how the carbon skeleton of glucose changes as it proceeds through glycolysis.

In glycolysis, the skeleton will change in two ways. The ring must be opened, and then the glucose will be cleaved into 2 3-carbon molecules known as glyceraldehyde. These are straight chained.

Explain why ATP is required for the preparatory steps of glycolysis.

Two molecules of ATP are consumed as glucose is split into two three-carbon sugars (glyceraldehyde 3-phosphate).The conversion of these molecules to pyruvate produces two NADH and four ATP by substrate-level phosphorylation.

Identify where substrate-level phosphorylation and the reduction of NAD+ occur in glycolysis.

SUBSTRATE-LEVEL PHOSPHORYLATION for ATP synthesis = enzyme-catalyzed transfer of phosphate groups from substrate to ADP for ATP synthesis (Reactions 7 and 10 of Glycolysis)--- Pi added to substrates from ATP hydrolysis in endergonic reactions-- Pi is transferred from substrates with high energy bonds to ADP forming ATP

Describe where pyruvate is oxidized to acetyl CoA, what molecules are produced, and how this process links glycolysis to the citric acid cycle.

Fate of pyruvate depends on availability of oxygen= Much more ATP from complete oxidation of glucose ---Aerobic=shuttles carry NADH into mitochondria; pyruvate can be oxidized to Acetyl CoA and enter TCA—or Anaerobic: pyruvate reduced by NADH to lactate, NAD+, H

List the products of the citric acid cycle. Explain why it is called a cycle.

products = CO2 (2 X 1C per acetyl-CoA. ----NADH + H+ (6 molecules / glucose molecule) --- FADH2 (2 molecules / glucose molecule). It is called citric acid because energy in acetyl CoA (2C) drives reaction of acetate (2C) with oxaloacetate (4C) to produce citrate (6C) = 1st reaction of Citric Acid Cycle. followed by a series of 8 reactions in which citrate (6C) is oxidized and oxaloacetate (4C) is regenerated with release of 2 molecules of CO2 (2 X 1C)--- completely oxidizes acetyl-CoA to two CO2 produce 2 acetyl-CoA per glucose molecule used in glycolysis (= producing 4 CO2)..... Reactants= acetyl-CoA (2C) from Pyruvate Oxidation, NAD+ - FAD (Flavin) ADP and Pi water... ENERGY= stored in NADH + H+ and FADH2 ATP (2 ATP per glucose molecule)

Describe the point at which glucose is completely oxidized during cellular respiration.

glucose is completely oxidized when all the energy is transfer to the 6 NADH & 2 FADH2

Distinguish between substrate level phosphorylation and oxidative phosphorylation.

OXIDATIVE PHOSPHORYLATION= PMF causes protons to diffuse back into mitochondrial matrix through membrane channel protein (= ATP synthase) that couples facilitated diffusion to ATP production. substrate-level phosphorylation = direct synthesis of ATP by direct transfer of phosphate group occurs in glycolysis

In general terms, explain how the exergonic "slide" of electrons down the electron transport chain is coupled to the endergonic production of ATP by chemiosmosis.

involves - 4 large proteins small protein (cyt c) - non-protein = ubiquinone (Q)/ free energy level decreases through ETC/ free energy stored in ATP/ excess electrons accepted by O2 forming H2O.

Explain why ATP synthase is considered a molecular rotary motor.

While the protons diffuse through it, it actually spins to make room for another proton to come through.

Explain where and how the respiratory electron transport chain creates a proton gradient. Explain why this gradient is described as a proton motive force.

The electron transport chain pumps protons from the matrix of the mitochondrion through the inner membrane and out to the intermembrane space (the interior of the cristae). The interior of the cristae becomes positively charged relative to the mitochondrion matrix, which creates a strong electrochemical gradient which favors the movement of protons back into the matrix.

summarize the net energy yields (atp, nadh, and fadh2) from the oxidation of a glucose molecule by constructing an energy ledger

Glycolysis--2 net ATP from substrate-level phosphorylation

2 NADH yields 6 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation;Transition Reaction--2 NADH yields 6 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation;Citric Acid Cycle--2 ATP from substrate-level phosphorylation

6 NADH yields 18 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation 2 FADH2 yields 4 ATP (assuming 2 ATP per FADH2) by oxidative phosphorylation

Total Theoretical Maximum Number of ATP Generated per Glucose in Prokaryotes--38 ATP: 4 from substrate-level phosphorylation; 34 from oxidative phosphorylation; In eukaryotic cells, the theoretical maximum yield of ATP generated per glucose is 36 to 38, depending on how the 2 NADH generated in the cytoplasm during glycolysis enter the mitochondria and whether the resulting yield is 2 or 3 ATP per NAD

Distinguish between fermentation and anaerobic respiration.

Fermentation: Occurs without oxygen, is the partial degradation of sugars to release energy; A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

Anaerobic respiration: The use of inorganic molecules other than oxygen to accept electrons at the "downhill" end of electron transport chains.

State the basic function of fermentation

A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

Compare the fate of pyruvate in alcohol fermentation and lactic acid fermentation

In alcoholic fermentation, pyruvic acid is converted to ethanol. Carbon dioxide is released, and NADH is recycled into NAD+. In lactic acid fermentation, pyruvic acid is converted to lactic acid. NADH is recycled into NAD+

Compare the processes of fermentation and cellular respiration

Fermentation is the process of deriving energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound.

This is in contrast to cellular respiration, where electrons are donated to an exogenous electron acceptor, such as oxygen, via an electron transport chain

Describe how food molecules other than glucose can be oxidized to make ATP

Each NADH and FADH2 molecule formed represents stored energy... contain high energy electrons from food molecules which are carried to an electron transport chain; Plants manufacture their own food by photosynthesis using energy from sunlight. Cells harvest the chemical energy stored in organic molecules and use it to regenerate ATP, the molecule that drives most cellular work. ADP + P + energy ATP

Distinguish between obligate and facultative anaerobes.

A facultative anaerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent. An obligate aerobe, by contrast, cannot make ATP in the absence of oxygen, and obligate anaerobes die in the presence of oxygen.

Explain how glycolysis and the citric acid cycle can contribute to anabolic pathways

Glycolysis and the citric acid cycle contribute by making ATP, they also generate electrons for the Electron Transport Chain (ETC). The ETC then uses those electrons to make a proton gradient in the mitochondria which in turn powers the enzyme ATP-synthase to make a whole bunch of ATP.

Define reduction (RIG)

The addition of electrons
Reduction Is Gain

When compounds lose electrons, they _________ energy

Lose

When compounds gain electrons, they _________ energy.

Gain