Chapter 7 Cellular Respiration

Question 1

Where is the Electron Transport Chain located? What is it consist of?

Answer 1

The ETC is located in the inner mitochondrial membrane.

It consists of mostly multi-protein complexes.

Question 2

How is energy in NADH and FADH2 released in the ETC?

Answer 2

The energy is released in a series of redox reactions that occur as electrons pass through the chain of protein complexes to the final electron acceptor, oxygen, which is reduced to H2O.

Question 3

What is the flow of electrons coupled with in the ETC?

Answer 3

The flow of electrons is coupled to the pumping of protons across the inner mitochondrial membrane, creating a concentration and an electrical gradient.

Question 4

What does the electrochemical grandient provide?

Answer 4

Provides a source of potential energy used to drive the regeneration of ATP.

Question 5

Describe how protons diffuse out from the intermembrane space and into the mitochondrial matrix.

Answer 5

Protons in the intermembrane space are able to diffuse down their electrical and concentration gradients through a protein channel called ATP Synthase into the mitochondrial matrix.

Question 6

What are the two components of ATP Synthase?

Answer 6

Fo subunit forms a channel that rotates as protons pass throught it.

F1 subunit then uses this rotational energy to catalyze the synthesis of ATP.

Question 7

Summarize the flow of energy in cellular respiration.

Answer 7

Most of the energy is transferred to electron carriers. These carriers donate electrons to the electron transport chain. That energy is used to pump protons across the inner membrane of the mitochondria. The energy of electron carriers is transformed into energy stored in prton electrochemical gradient. ATP Synthase converts the energy of the proton gradient to rotational energy, which drives the regeneration of ATP.

Question 8

What was the net energy yield from the oxidative phosphorylation?

Answer 8

28 ATP

Question 9

Where is the ETC located?

Answer 9

Inner mitochondrial membrane

Question 10

What happens in the preparatory phase in glycolysis?

Answer 10

Glucose is prepared by the addition of 2 phosphate groups and an input of 2 ATP producing fructose 1,6 - biphosphate.

Question 11

What happens in the cleavage phase in glycolysis?

Answer 11

Fructose 1,6 - biphosphate is split into two molecules of glyceraldehyde 3 - phosphate.

Question 12

What happens in the payoff phase in glycolysis?

Answer 12

2 pyruvate molecules are formed and 2 NADH molecules are produced.

Question 13

What happens in Acetyl-CoA Synthesis

Answer 13

In the presence of oxygen, pyruvate is transported into the mitochondrial mattix where it is converted to acetyl-CoA.
Pyruvate is oxidized to form acetyl group and CO2
The acetyl group is transferred to coenzyme A forming Acetyl-CoA, which is carried to the citric acid cycle.
2 NADH and 2CO2 are produces per glucose molecule.

Question 14

Where does the Acetyl-CoA Synthesis take place?

Answer 14

Mitochondrial matrix

Question 15

What stage does gluclose become completely oxidized?

Answer 15

In the citric acid cycle.

Question 16

What molecule is regenerated at the end of the citric acid cycle?

Answer 16

Oxaloacetate is regenerated at the end of the citric acid cycle.

Question 17

Where does the energy in the bonds of acetyl-CoA go?

Answer 17

The chemical energy in the bonds of acetyl-CoA is transferred to ATP by substrate level phosphorylation and to the electron carriers NADH and FADH2.

Question 18

What is the first step of the citric acid cycle?

Answer 18

The two xarbon lart of Acetyl-CoA is added to oxaloacetate for citrate.

Question 19

What happens in steps 3 and 4 in the citic acid cycle?

Answer 19

The oxidation of carbon atoms to produce CO2 is coupled with the reduction of NAD+ and FAD to their reduced forms.

Question 20

What is the net energy yield of the citric acid cycle per glucose molecule?

Answer 20

6NADH 2FADH 2ATP and 2 CO2

Question 21

What are the 3 ways to obstruct the process of oxidative phosphorylation?

Answer 21

1. Block the ETC. E.g rotenone, cyanide, carbon monoxide.
2. Block the flow of H+ through the ATP Synthase, e.g. The antibiotic Oligomycin.
3. Make the membrane leaky to H+ e.g. Dinitriophenol.

Question 22

Why was dinitriophenol used as a diet pill in the 1930s?

Answer 22

DNP would make you burn more glucose to produce a certain concentration of ATP.

Question 23

What is brown fat? What is its functions?

Answer 23

Brown fat is a special type if fat tissue associated with the generation of heat.
In brown fat, the cells the packed with mitochondria.
The inner mitochondrial membrane contains a protein, which allows H+ to flow back down its concentraion gradient without generateing ATP, but generating heat.

Question 24

How do cells regulate cellular respiration?

Answer 24

The level of ATP in the cell is an indicator of how much energy a cell has available. When ATP levels are high, the cell DOWN REGULATES the pathways leading to ATP synthesis.
When ATP levels are low or ADP levels are high, the cell UP REGULATE the pathways that lead to ATP synthesis.

Question 25

What happens if the cell has high levels of NAD+?

Answer 25

The cell up-regulates the pathways that leas to ATP synthesis.

Question 26

What happens if the cell has high levels of NADH?

Answer 26

The cell down-regulates pathways that lead to ATP synthesis.

Question 27

What stage of cellular respiration can produce ATP without oxygen?

Answer 27

Glycolysis occurs anaerobically.

Question 28

What is anaerobic respiration?

Answer 28

Uses an electron transport chain with an electron acceptor other than oxygen, such as sulphate or nitrate.( they have high electronegativity)

Question 29

What is fermentation?

Answer 29

Uses substrate level phosphorylation instead of oxidative phosphorylation to regenerate ATP.
Fermentation consists of glycolysis plus reactions that REGENERATE NAD+ so it can be reused by glycolysis.

Question 30

How many ATP does fermentation produce per glucose molecule?

Answer 30

2 ATP per glucose molecule.

Question 31

What is lactic acid fermentation?

Answer 31

Glycolysis plus a reaction that regenerates NAD+.

Electrons from NADH are transferred to pyruvate to produce lactic acid and NAD+

Question 32

What happens in alcohol fermentation?

Answer 32

Glycolysis plus a reaction thag regenerates NAD+.
Pyruvate releases CO2 to form acetyldehyde, and electrons from NADH are transferred to acetyldehyde to produce ethanol and NAD+.

Question 33

Where do electrons come from in the mitochondria?

Answer 33

Glucose.

Question 34

How do electrons get their high potential energy in the mitochondria?

Answer 34

Shared in covalent bonds.

Question 35

What picks up electrons at the end of the chain in mitochondria?

Answer 35

O2.

Question 36

How is the energy given up by the electrons used in mitochondria?

Answer 36

Energy released in redox reactions in the ETC is used to transport H+ across the inner mitochondrial membrane. The flow of H+ down its electrochemical concentration gradient back through across ATP Synthase drives the phosphorylation of ADP to ATP.