3.6: Cellular Respiration

Question 1

What is Fermentation? Identify the products of fermentation.

Answer 1

Uses glucose to release chemical energy in the absence of oxygen. It produces some ATP, lactic acid or CO2 and ethanol.

Question 2

What is the process of cellular respiration? Identify the products of cellular respiration.

Answer 2

Uses glucose to release chemical energy in the presence of oxygen. It produces H20, CO2, and ATP.

Question 3

What is the electron transport chain?

Answer 3

It transfers energy from electrons in a series of coupled reactions. Then ATP synthase uses the proton gradient to synthesize ATP in chemiosmosis into the inner membrane space. It is a more efficient way of generating energy.

Question 4

Identify the three locations of electron transport chains in cells?

Answer 4

Mitochondria (cellular respiration), chloroplast (photosynthesis), and cell membranes of prokaryotes.

Question 5

What is the pathway of electrons through cellular respiration?

Answer 5

1. Glycolysis-cytoplasm, use ATP to make NAD+ into NADH and produce pyruvate.
2. Pyruvate Oxidation-mitochondria, link between Glycolysis and Krebs Cycle that adds takes energy from the pyruvate to produce NADH so that there aren’t too many electrons.
3. Krebs/Citric acid cycle-mitochondria, adds FADH2 and NADH so that the electron transport chain will function.
4. Electron transport chain-mitochondria-creates a H gradient and produces ATP through chemiosmosis by the end, with O2 acceptor.

Question 6

Identify the final electron chain for photosynthesis and cellular respiration.

Answer 6

Oxygen (cellular respiration), NADPH (photosynthesis)

Question 7

How do electrons move through the electron transport chain?

Answer 7

Going to a step adds electrons (reduction), while electrons leaving the step is oxidation. They are delivered to “each step” by electron carriers called NADH and FADH2. During oxidation in each step of the ETC, a H+ gradient is formed.

Question 8

What process generates the proton gradient?

Answer 8

During oxidation in each step of the ETC, a H+ electrochemical gradient is formed.

Question 9

What direction do the protons get pumped to generate the proton gradient in cellular respiration?

Answer 9

The protons get pumped to the intermembrane space. They then go through ATP synthase and into the inner mitochondrial membrane as ATP.

Question 10

How does the proton gradient affect the pH of the area?

Answer 10

The more H+ ions, the lower and more acidic the pH is.

Question 11

Identify two differences between the the electron transport chain in prokaryotes and eukaryotes.

Answer 11

Eukaryotes-ETC inner mitochondrial membrane or internal chloroplast membrane

Prokaryotes- ETC located in the plasma membrane

Question 12

What is chemiosmosis?

Answer 12

H+ protons diffuse across the mitochondrial membrane into the inner membrane space by ATP synthase. (part of ox phos)

Question 13

What is photophosphorylation?

Answer 13

Using light energy to convert ADP to ATP using photosynthesis.

Question 14

What is an endotherm? How do they maintain their body temperature?

Answer 14

They are not dependent on the environment to regulate their body temperature. Instead, they decouple oxidative phosphorylation to create heat.

Question 15

What is decoupling oxidative phosphorylation? How does it generate heat?

Answer 15

The ETC occurs, but then the proton gradient is not used for chemiosmosis. Instead of going through the ATPase, the H+ protons diffuse through the membrane, creating heat.

Question 16

How do ectotherms regulate their body temperature?

Answer 16

They use energy from the OUTSIDE to regulate their body temperature

Question 17

What is glycolysis? What are the starting materials? What are the products? Where does it take place in the cell?

Answer 17

Releases energy stored in glucose. It uses glucose, ATP and NAD+ to produce ATP, NADH and Pyruvate. It occurs in the cytosol.

Question 18

Based on the location of glycolysis, what statement can be made about evolutionary history?

Answer 18

Early prokaryotes would have used glycolysis to release energy stored in glucose, as this takes place in the cytoplasm. Also, there was not much oxygen in the atmosphere at the time, so this would have been the only way to release stored energy. Later steps including Pyruvate oxidation, the krebs cycle, and ox phos would have developed later as they occur in the mitochondria.

Question 19

What is the Krebs Cycle? What are the starting materials? Where does it take place in the cell?

Answer 19

It adds to the NADH used to let the ETC function. It uses oxidized pyruvate, NAD+ and FAD and releases CO2, ATP, NADH, and FADH2.

Question 20

How are electrons transported to the ETC?

Answer 20

NADH and FADH2 carrier molecules bring electrons from the Krebs Cycle and Glycolysis to the ETC.

Question 21

Where is the ETC located?

Answer 21

The inner mitochondrial membrane. (H+ on the intermembrane side and ATP on the inner membrane side).

Question 22

What occurs as electrons are transferred from one cytochrome to the next in the ETC?

Answer 22

FADH or NADH is returned back to NAD+ and FAD+ and a proton gradient.

Question 23

What is the function of fermentation? What are the products?

Answer 23

Glycolysis proceeds in the absence of oxygen. The products are lactic acid to ethanol.

Question 24

What is the function of ATP hydrolysis?

Answer 24

Hydrolysis means that bonds are breaking, so when a phosphate molecule breaks off from ATP, it releases energy.