1. Topic 2.8 Review

2. Essential idea: Cell respiration supplies energy for the functions of life.

3. U2.8.1: Cell respiration is the controlled release of energy from organic compounds to produce ATP.
What is cellular respiration?
Cellular respiration is the controlled release of energy from organic compounds. This energy is then used to produce ATP.
What types of compounds are broken down?
Carbohydrates, lipids and proteins.
Where is the energy found in these molecules?
Within the bonds between atoms.
What type of process is cellular respiration: anabolic or catabolic?
Catabolic
Is cellular respiration oxidation or reduction?
Oxidation (LEO = lose electrons, oxidation)
What kinds of processes require ATP?
Active transport, anabolic processes, and cellular division

4. Cellular respiration
C6H12O6 + 6 O2  6 CO2 + 6 H2O + ATP

5. U2.8.2: ATP released from cell respiration is immediately available as a source of energy in the cell.
What is the structure of ATP?
ATP contains adenosine (a combination of adenine and ribose) and three phosphate groups held together in close proximity by bonds.
Why does ATP supply energy?
The three phosphates are all negatively charged. Being in close proximity is like compressing a spring; it’s loaded with potential energy.
When energy is needed, hydrolysis removes the last phosphate, releasing energy and leaving ADP (adenosine diphosphate) and Pi (inorganic phosphate).
Why is ATP a good source of energy currency for cells?
The ATP can be transported anywhere in the cell, and can rapidly release its energy.

6. U2.8.4: Aerobic cell respiration requires oxygen and gives a large yield of ATP from glucose.
What process is common to both aerobic and anaerobic respiration?
Glycolysis
What molecule serves as the reactant for glycolysis?
Glucose
How much ATP is produced via this process?
A net gain of 2 ATP molecules (4 are made, but 2 are required during the process)
What other products are made via glycolysis?
2 pyruvates and 2 molecules of NADH
If oxygen is present, where do the pyruvates go?
The mitochondrion

7. Prior to entering the mitochondrion, what happens to the pyruvates?
They are converted into acetyl-CoA, which involves the release of carbon dioxide.
Once in the mitochondrion, what process does acetyl-CoA go through?
The Krebs cycle
What is the specific location of the Krebs cycle?
The mitochondrial matrix
What is the net result of the Krebs cycle?
2 molecules of ATP, 6 molecules of NADH, 2 molecules of FADH2, and 4 molecules of CO2
What process follows the Krebs cycle?
Oxidative phosphorylation and the electron transport chain
What is the role of oxygen in this process?
It is the final electron acceptor at the end of the ETC and drives the movement of the electrons from NADH and FADH2 down the chain.
How many ATP are produced from this final process?
About 34

9. S2.8.1: Analysis of results from experiments involving the measurement of respiration rates in germinating seeds or invertebrates using a respirometer.
What is a respirometer?
A device used to measure respiration rates
How does it measure the rate of respiration?
It looks at either the production of carbon dioxide, or the consumption of oxygen
What would you expect to observe if the rate of respiration of germinating vs. non- germinating peas was measured?
Since germinating peas are actively growing, which requires ATP, you would expect to see more carbon dioxide produced and more oxygen consumed.
What would be the effect of chilling the germinating peas?
The rate of respiration would be reduced, as the enzymes required for respiration are not at an optimal temperature.

10. U2.8.3: Anaerobic respiration gives a small yield of ATP from glucose.
What is lacking in anaerobic respiration?
Oxygen
How much ATP total is produced by anaerobic respiration?
2 molecules of ATP
What is the purpose of anaerobic respiration?
To continue to produce some ATP in the absence of oxygen
What are two types of anaerobic respiration?
Lactic acid (lactate) fermentation
Alcoholic fermentation
What does anaerobic respiration accomplish?
It replenishes the supply of NAD+ by converting pyruvate into either lactate or ethanol, which oxidizes the NADH, allowing for the continuation of glycolysis

11. A2.8.1: Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.
What is the purpose of using yeasts in baking?
Yeasts go through fermentation in the absence of oxygen, and produce ethanol and carbon dioxide. This allows bread to rise.
What is the function of yeasts in ethanol production?
When the yeasts are suspended in liquid and given sugar as a source of fuel, but oxygen is not supplied, they’ll produce ethanol (alcohol) and carbon dioxide. This can be used in beer and wine. Ethanol can also be used a source of fuel for vehicles.

12. A2.8.2: Lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions.
Why do our muscle cells go through fermentation?
To continue to produce ATP in the absence of oxygen, such as during intense exercise.
What product is made?
Lactic acid (or lactate).
What happens if the exercise continues during lactic acid fermentation?
The muscles will eventually cramp.
What happens to the lactate?
It’s eventually shuttled to the liver, converted back into pyruvate, and when oxygen is available, will proceed through aerobic respiration.