Metabolism

Question 1

What types of molecules play a big role in metabolism?

Answer 1

Enzymes and transporters

Question 2

What are the two types metabolic pathways? Describe them.

Answer 2

1) Anabolism - building up new molecules

2) Catabolism - breaking down existing molecules

Question 3

What are the principles of thermodynamics which metabolism is constrained by? (2)

Answer 3

1) Energy cannot be created or destroyed

2) Entropy only ever increases

Question 4

What are the three types of work in a cell? Describe them.

Answer 4

1) Chemical - pushing endergonic reactions
2) Mechanical - movement
3) Transport - pumping things across the membrane

Question 5

What are redox reactions?

Answer 5

transfer of electrons from one molecule to another

Question 6

What does negative/positive sign of E0 say about the reaction? (Energy released?)

Answer 6

Positive: endothermic (absorbs energy)
Negative: exothermic (releases energy)

Question 7

What is the most commonly oxidized compound in biological system?

Answer 7

Carbon

Question 8

“the more reduced a compound is, the more ________ _________ that can be released by oxidation.”

Answer 8

potential energy

Question 9

Which is more oxidized? Lipids or carbohydrates?

Answer 9

carbohydrates

Question 10

In biological systems, what are redox reactions typically coupled to?

Answer 10

electron carriers

Question 11

What are primary electron donors?

Answer 11

the initial doner of electrons

Question 12

What are terminal electron acceptors?

Answer 12

the final recipient of electrons

Question 13

What are the two types of electron carriers? Describe them.

Answer 13

1) freely diffusable - they diffuse to the enzyme

2) Attached - they are bound to the enzyme

Question 14

What is an example of freely diffusible carriers? (3)

Answer 14

NAD+/NADH
FAD/FADH2
NADP+/NADPH

Question 15

What is an example of attached electron carrier?

Answer 15

coenzyme Q

Question 16

What are exergonic reactions? Endergonic?

Answer 16

Exergonic - releases energy

Endergonic - consumes energy

Question 17

Is ATP hydrolysis exergonic or endergonic?

Answer 17

exergonic

Question 18

How do enzymes couple the energy released by the hydrolyze of ATP to other reactions to drive the reaction forward?

Answer 18

by transferring the phosphate group to the other substrate

Question 19

What does positive/negative sign of ΔG say regarding if energy is released or consumed?

Answer 19

Positive - energy consumed

Negative - energy released

Question 20

What are two processes where ATP is generated in chemotrophs?

Answer 20

1) Fermentation - redox without terminal electron acceptors

2) Respiration - redox with terminal electron acceptors (eg oxygen)

Question 21

What are the two molecular level mechanisms which generates ATP?

Answer 21

1) Substrate level phosphorylation

2) Oxidative phosphorylation

Question 22

Where does oxidative phosphorylation occur for in animal cells and plant tissues?

Answer 22

mitochondria

Question 23

What is the overall reaction for cellular respiration?

Answer 23

C6H12O6 + 6O2 —> 6CO2 + 6H2O

glucose

Question 24

Why does the cell slow down the glucose redox reaction?

Answer 24

since oxygen is highly reactive and so the reaction happens very fast, which would waste a lot of energy

Question 25

What are three main pathways that work together to degrade glucose and harvest the energy?

Answer 25

1) Glycolysis 2) Tricarboxylic acid cycle (TCA) 3) Electron transport chain (ETC)

Question 26

Where does glycolysis occur in bacteria and eukaryotic cells?

Answer 26

cytosol

Question 27

What is stage three of glycolysis and fermentation? (2)

Answer 27

1) fermentative pathway or | 2) continue to TCA cycle and ETC

Question 28

Why is glycolysis and fermentation substrate level phosphorylation?

Answer 28

Has enzymes involved

Question 29

What happens to the pyruvate produced from the glycolysis if oxygen is present?

Answer 29

Goes to the TCA cycle and ETC

Question 30

What happens to the pyruvate produced from the glycolysis if NO oxygen is present?

Answer 30

fermentation to make ATP and regenerate NAD+

Question 31

What is an example of when human cells will use fermentation?

Answer 31

During exercise when oxygen is temporarily unavailable

Question 32

How is pyruvate converted to acetyl-coA?

Answer 32

decarboxylation

Question 33

Where does TCA occur in eukaryotes? In bacteria?

Answer 33

Eukaryotes - mitochondria | Bacteria - cytosol

Question 34

When pyruvate is transported from the cytosol into the mitchondria, what is the cost?

Answer 34

1 ATP per pyruvate

Question 35

What makes up the ETC?

Answer 35

series of membrane proteins that are also electron carriers

Question 36

Where does ETC occur in eukaryotes? In bacteria?

Answer 36

Eukaryotes - inner mitochondria membrane | Bacteria - plasma membrane

Question 37

Why does NAD+ make more ATP than FADH2?

Answer 37

NAD+ enters ETC earlier and can pump more H+ across the membrane which makes more ATP

Question 38

How is the concentration gradient created in ETC?

Answer 38

the movement of H+ from one side of the membrane

Question 39

What is the proton motive force?

Answer 39

the electrochemical gradient created by H+

Question 40

What is the enzyme that produces ATP? What is it known as?

Answer 40

- ATP synthase | - Smallest known motor

Question 41

Which metabolism method (ETC or fermentation) is the most efficient? Why don't cells prefer that metabolism method the most?

Answer 41

- Fermentation | - Energy is stored in lactid acid which is harmful at high conc

Question 42

When do cells use anaerobic respiration? (2)

Answer 42

When: 1) ATP must be made quickly 2) O2 is not available

Question 43

Where does the photosynthetic machinery occur?

Answer 43

chloroplast stroma

Question 44

What are the main differences between ETC and photosynthesis? (2)

Answer 44

1) the electrons are supplied by the hydrolysis of water | 2) electrons are excited by light

Question 45

What is the only enzyme in the world known to hydrolyze water?

Answer 45

Photosystem II

Question 46

Are all the O2 produced by the plant released into the atmosphere?

Answer 46

No...plants also use respiration

Question 47

What is the purpose of the calvin cycle?

Answer 47

- In case light is limited ATP must be stored in another form - ATP is used to fix inorganic carbon into carbohydrates

Question 48

What is the most important enzyme in Calvin cycle?

Answer 48

Rubisco!