Chapter 7

Question 1

What is cellular respiration?

Answer 1

The release of energy from molecules such as glucose.

Question 2

What is glucose?

Answer 2

A high energy molecule that as it is broken down, energy is released. The energy released is used to make ATP.

Question 3

What do the different pathways of cellular respiration do?

Answer 3

Allow energy within a glucose molecule to be released slowly for ATP synthesis.

Question 4

What does cellular respiration involve?

Answer 4

Many individual reactions which each require its own enzyme.

Question 5

What is co-enzyme?

Answer 5

Specific molecules that help certain enzymes like NAD+ and FAD.

Question 6

What does each coenzyme carry?

Answer 6

2 electrons and 2 hydrogen atoms.

Question 7

What do coenzymes do at specific enzymatic reactions?

Answer 7

Pick up electrons and carry them to the electron transport chain then eventually lose electrons at electron transport chain, lots of energy is released as a result.

Question 8

What happens when NAD+ is loaded.

Answer 8

It becomes reduced and becomes NADH + H+

Question 9

What happens when FAD is reduced?

Answer 9

It becomes FADH2.

Question 10

What are the different phases of cellular respiration?

Answer 10

Glycolysis, preparatory reaction, citric acid cycle, and electron transport chain.

Question 11

What is glycolysis?

Answer 11

The breakdown of glucose into 2 molecules of pyruvate. This breakdown causes removal of electrons and H+ and provides energy for 2 ATP. Occurs if there is oxygen or not.

Question 12

Describe the process of glycolysis

Answer 12

First step is to break 6 glucose into 2 G3P molecules at the cost of 2 ATP into ADP. The G3P molecules have a phosphate group attached. Then, a further reaction where G3P molecules each become a pyruvate molecule.

Question 13

Describe Glycolysis if Oxygen is present.

Answer 13

It occurs in cytoplasm, made a net gain of 2 ATP molecules and 2 NADH molecules. With oxygen present, pyruvate goes to mitochondria and becomes aerobic cellular respiration. The NADH made in glycolysis also goes to mitochondria.

Question 14

Describe Glycolysis if oxygen is not present.

Answer 14

It stays in the cytoplasm, will undergo fermentation.

Question 15

What are the inputs of glycolysis?

Answer 15

6C glucose, 2 NAD+, 2 ATP, 4 ADP + 4P

Question 16

What are the outputs of glycolysis?

Answer 16

2 3C pyruvate, 2 NADH, 2 ADP, 4 ATP total

Question 17

Describe prep reaction.

Answer 17

Pyruvates with oxygen present move into cristae of mitochondria. Each pyruvate reacts and links to a co-enzyme A molecule. During this reaction, each pyruvate loses a CO2 molecule. We call the new oxidized molecule acetyl CoA. There are 2 NADH molecules made in this reaction.

Question 18

Describe the citric acid cycle.

Answer 18

Cyclical series of oxidation reactions that produce one ATP and carbon dioxide per turn. Acetyl CoA is converted to citric acid and enters the cycle. Citric acid cycle turns twice because 2 acetyl CoA’s are produced per glucose. There are various reactions, but each citric acid loses 2 C’s with each becoming CO2. You get an ATP, FADH2 and 3 NADH’s.

Question 19

Describe the change of Acetyl CoA to citric acid.

Answer 19

Occurs in the mitochondria. CoA leaves, and you start with the 2C acetyl when it joins with a 4C molecule and becomes citric acid.

Question 20

What are the inputs of the citric acid cycle?

Answer 20

2 acetyl groups, 6 NAD+, 2 FAD, 2 ADP + 2 P’s.

Question 21

What are the outputs of the citric acid cycle?

Answer 21

4 CO2, 6 NADH +H+, 2 FADH2, 2 ATP

Question 22

Describe the electron transport chain

Answer 22

Series of electron carrier molecules, electrons are passed from 1 carrier to another, as the electrons move from a higher energy state to a lower one, energy is released to make ATP. It occurs in the cristae. FADH2 becomes FAD, and NADH becomes NAD.

Question 23

What happens at the very end of the chain?

Answer 23

The much reduced energy e- at the end of chain combine with oxygen. H2O is formed then leaves.

Question 24

What happens during electron transport chain?

Answer 24

H+ that was released from NADH and FADH2 accumulates in the intermembrane space of the cristae.

Question 25

Explain chemiosmosis

Answer 25

Has to do with H+ instead of water moving across semi-permeable membrane. It is also that energy associated with H+ movement gets captured in ADP to ATP reaction.

Question 26

What happens when glycolysis occurs with no oxygen?

Answer 26

Fermentation occurs. Pyruvate is reduced to lactate in animals and alcohol in plants. Fermentation results in a net gain of 2 ATP/glucose.

Question 27

How does lactic acid fermentation occur?

Answer 27

In animal cells, pyruvate from glycolysis accepts two hydrogen ions and two electrons and is reduced to lactate. The 2 NADH pass electrons to pyruvate to reduce it to lactate.

Question 28

Why does fermentation happen?

Answer 28

Fermentation is essential to humans since it can provide a rapid burst of ATP.

Question 29

What are some problems with lactic acid?

Answer 29

Lactate is toxic to cells, and as it accumulates, lactate changes the pH of the muscle cells causing the “burn” feeling.

Question 30

Describe alcohol fermentation.

Answer 30

Yeast generates ethyl alcohol fermentation. Electrons needed to reduce the pyruvate are supplied by NADH molecules. Unlike lactic acid fermentation, alcohol fermentation releases small amounts of carbon dioxide.

Question 31

What is the energy yield of fermentation.

Answer 31

Very low yield, fermentation yields only 2 ATP by substrate-level ATP synthesis. These 2 ATP represent a small fraction of potential energy stored in glucose. In cellular respiration with oxygen present, 36-38 ATP molecules are produced. In fermentation, most of the potential energy stored in glucose has not been released.