Cellular Energy

Question 1

Where does glycolysis occur?

Answer 1

The cytosol

Question 2

Fermentation is an __________ pathway/process

Answer 2

Anaerobic

Question 3

What does fermentation rely on?

Answer 3

Glycolysis

Question 4

What is the primary purpose of fermentation?

Answer 4

To oxidize NADH back to NAD⁺ so that glycolysis can continue to make ATP —> regenerating NAD⁺ means that glycolysis can continue to make ATP

Question 5

Lactic acid fermentation

Answer 5

Oxidizes 2 NADH from glycolysis back to NAD⁺ by reducing the 2 pyruvate into 2 lactic acid
Oxidation of NADH will transfer its electrons to pyruvate which regenerates NAD⁺

Question 6

The Cori cycle

Answer 6

Converts lactate back into glucose once oxygen becomes available again

Question 7

The Cori cycle in myocytes

Answer 7

The Cori cycle transports lactate from the myocyte (muscle cells) to the liver cells (hepatocytes), where it is oxidized back into pyruvate. Pyruvate can then be used to form glucose through gluconeogenesis which can be used for more ideal energy generation

Question 8

Alcohol fermentation

Answer 8

Uses 2 NADH from glycolysis to convert the 2 pyruvate into 2 ethanol and therefore oxidizing NADH back to NAD⁺ but WITHOUT reducing pyruvate

Question 9

How does alcohol fermentation regenerate NADH?

Answer 9

1. 2 pyruvate are decarboxylated and lose 2 CO₂ molecules, converting into acetaldehyde
2. Acetaldehyde is reduced by NADH into ethanol and thereby oxidizing NADH to NAD⁺

Question 10

Obligate aerobes

Answer 10

Organisms that can only metabolize using aerobic respiration —> oxygen must be present in order to survive

Question 11

Obligate anaerobes

Answer 11

Organisms that only metabolize their fuel source via anaerobic respiration or fermentation, oxygen is toxic

Question 12

Facultative anaerobes

Answer 12

favor aerobic respiration because it generates the most ATP, BUT can utilize anaerobic respiration or fermentation

Question 13

Microaerophiles

Answer 13

only perform aerobic respiration (oxygen present) BUT high concentrations of oxygen are harmful to them

Question 14

Aerotolerant organisms

Answer 14

Only undergo anaerobic respiration or fermentation, but oxygen is not poisonous to them

Question 15

lipolysis

Answer 15

Digesting triglyceride with a lipase

Question 16

Lipase

Answer 16

Enzymes that break down triglycerides

Question 17

What are the products of oxidative phosphorylation?

Answer 17

NAD⁺
FAD
H₂O
ATP

Question 18

What can glycerol be directly converted into?

Answer 18

When a glycerol molecule travels to the liver:
it can be converted to glucose via gluconeogenesis to enter glycolysis
or it can be converted to glycogen via glycogenesis

Question 19

What is a waste product that is produced at the end of the ETC?

Answer 19

water
the final electron acceptor is oxygen. oxygen molecules combine with protons to form water

Question 20

What are the products of beta-oxidation?

Answer 20

Acetyl-CoA
NADH
FADH₂

Question 21

What do lipases convert triglycerides into?

Answer 21

Free fatty acids and alcohols (ex: glycerol molecules, monoglycerides)

Question 22

How many ATP molecules can be produced from one FADH₂ coenzyme?

Answer 22

2 ATP —> this is because FADH₂ reduces a later complex

Question 23

From one glucose, ________ pyruvate manipulations occur which produces:

Answer 23

2
Releases: 2 carbon dioxides
Reduces: 2 NAD⁺ into 2 NADH
Produces: 2 acetyl-CoA

Question 24

What is the first step of pyruvate manipulation?

Answer 24

Decarboxylation: a pyruvate molecule (3-C) will be decarboxylated to release a carbon atom as carbon dioxide

Question 25

Where in the cell does pyruvate manipulation take place?

Answer 25

Mitochondrial matrix

Question 26

Where is the electron transport chain located in prokaryotic cells?

Answer 26

Along the cell membrane

Question 27

What is the net ATP yield for every glucose during fermentation?

Answer 27

2 ATP

Question 28

Why are carbohydrates a better fuel source than fatty acids?

Answer 28

Although fats yield 9 kcal/gram (as opposed to carbohydrates yielding 4 kcal/gram), carbohydrates are a better fuel source because it requires **much less energy input** to break up than fatty acids, which require much more energy input. Carbohydrates therefore are much easier for the body to digest and use for energy, which is why they are the first choice.

Question 29

Which process **directly** depends on oxygen?

Answer 29

**oxidative phosphorylation** directly depends on oxygen as the final electron acceptor of the aerobic ETCs.

Question 30

Which process **indirectly** depend on oxygen?

Answer 30

Aerobic pyruvate oxidation and the Krebs cycle

Question 31

Where do humans absorb digested fasts? What is the process?

Answer 31

Through the **enterocytes of the small intestine** - Free fatty acids and monoglycerides enter the cell - once contained within the enterocyte, the free fatty acids and monoglycerides will **reform into triglycerides** - once the triglycerides have reformed, they will pair up with proteins, phospholipids and cholesterol int the enterocytes

Question 32

Amino acid byproducts can enter cellular respiration at which molecules?

Answer 32

Depending on the starting amino acid, amino acid byproducts created via oxidative deamination can enter enter cellular respiration by converting to pyruvate, acetyl-CoA, and several of the Krebs cycle intermediates

Question 33

what organisms convert ammonia into uric acid before excretion?

Answer 33

Insects, reptiles and birds

Question 34

What is the net ATP yield for every glucose in fermentation?

Answer 34

2 ATP per glucose

Question 35

How can fatty acids travel in their free state in the bloodstream?

Answer 35

By binding to protein called albumin Free state = not esterified to glycerol

Question 36

During which process is FADH₂ produced?

Answer 36

The Krebs cycle

Question 37

Where does the Krebs cycle take place?

Answer 37

In the mitochondrial matrix

Question 38

How many ATP molecules can be produced from one FADH₂ coenzyme?

Answer 38

2

Question 39

Why is the process of oxidative phosphorylation labelled as “oxidative”?

Answer 39

Electron carriers, NADH and FADH₂, are *oxidized* in order to release high-energy electrons they carry

Question 40

Why do fatty acid chains have a high potential for ATP production compared to glucose?

Answer 40

Fatty acid chains contain many **highly reduced carbons**, which can contribute to the production of “bonus” electron carriers and acetyl-CoA through beta-oxidation

Question 41

What is the pathway that represents the movement of protons within the mitochondria to generate ATP?

Answer 41

Inter membrane space to the mitochondrial matrix

Question 42

What pathway represents the movement of protons within the mitochondria to generate a proton gradient?

Answer 42

Mitochondrial matrix to the intermembrane space

Question 43

Which body cells are capable of performing the Cori cycle?

Answer 43

**Liver cells (hepatocytes)**

Question 44

What are the 5 catabolic process?

Answer 44

Glycolysis - breaking down glucose Oxidative deamination - breaking down amino acids Glycogeonlysis - breaking down glycogen Lipolysis - breaking down triglycerides Beta oxidation - breaking down fatting acids

Question 45

during cellular respiration, what occurs in response to low glucose levels?

Answer 45

* glycolysis is inhibited through the inhibition of the enzymes hexokinases and glucokinases, which catalyze the first step of glycolysis

Question 46

in the small intestine, what are triglycerides broken down into?

Answer 46

* monoglycerides and fatty acids * catalyzed by the eznyme lipase