Chapter 4: Energy/Metabolism

Question 1

what is energy?

Answer 1

the capacity to do work

Question 2

Define kinetic energy.

Answer 2

the energy of motion

Question 3

Define potential energy.

Answer 3

Stored energy

Question 4

In what two ways is energy stored in the body?

Answer 4

1. Concentration gradients
2. Chemical Bonds

Question 5

Define reactant.

Answer 5

substance or compound that is added to a system in order to bring about a chemical reaction

Question 6

Define product.

Answer 6

Compounds formed during chemical reactions as reagents are consumed.

Question 7

Define reactant rate.

Answer 7

the speed at which a reaction takes place

equal to the disappearance rate of reactants or appearance rate of products

Question 8

Define exergonic

Answer 8

Releasing energy (usually as heat)

Question 9

Define endergonic.

Answer 9

Requiring a net input of energy, which often remains trapped in chemical bonds formed via the reaction.

Question 10

Define enzymes.

Answer 10

Proteins that speed up the rate of chemical reactions.

• they lower the activation energy for the reaction

Question 11

Define substrate.

Answer 11

the reactants in enzymatically catalyzed reactions

Question 12

Define coenzymes.

Answer 12

organic cofactors for enzymes

• they do not alter the binding sites of enzymes but rather act as receptors and carriers for atoms and functional groups removed from substrates

Question 13

Define phosphorylation.

Answer 13

the addition of a phosphate group

ex: ADP becomes ATP

Question 14

Define oxidation-reduction reaction.

Explain their metabolic significance.

Answer 14

the transfer of electrons from one molecule to another

they are important reactions in energy extraction and transfer in cells and occur throughout all three stages of respiration

Question 15

If a molecule gains electrons, what is it said to be?

Answer 15

Reduced

Question 16

If a molecule loses electrons, what is it said to be?

Answer 16

Oxidized

Question 17

define metabolism

Answer 17

all chemical reactions that take place in an organism

Question 18

define catabolism

Answer 18

reactions that release energy through the breakdown of large biomolecules

Question 19

define anabolism

Answer 19

energy-utilizing reactions that result in the synthesis of large biomolecules

Question 20

What are the three steps of cellular respiration?

Answer 20

1. Glycolysis
2. Krebs Cycle/Citric Acid Cycle/Keto Acid Cycle
3. Electron Transport Chain

Question 21

What are the major steps in glycolysis?

Answer 21

1. 6-C glucose enters cell via facilitated diffusion
2. 2 ATP are used to phosphorylate glucose into 1,6 - diphosphate fructose
3. Sugar cleavage occurs, breaking 6-C, 2-P molecule into two separate C-C-C-P molecules
4. each C-C-C-P molecule undergoes several reactions, producing 2 ATP and 1 NADH each for a total of 4 ATP and 2 NADH produced
5. The end product is two C-C-C pyruvic acid molecules which continue on to the citric acid cycle

Question 22

What is consumed and what is produced by glycolysis?

Answer 22

Consumed

• 1 glucose
• 2 ATP

Produced

• 2 NADH
• 4 ATP
• 1 H₂0
• 2 Pyruvate

Question 23

What are the major steps of the citric acid cycle and intermediate step?

Answer 23

1. the 2 pyruvates formed by glycolysis enter the mitochondrial matrix via double membrane
2. in the intermediate step between glycolysis and the cycle, each pyruvate is oxidized, giving off a NADH and CO2 and gaining Coenzyme A to form Acetyl-CoA
3. Acetyl-CoA enters the cycle, combines with 4-C product of previous cycle and forms 6-C citric acid
4. 6-C citric acid is oxidized, gives off NADH and CO₂, forms 5-C molecule
5. **5-C is oxidized, gives off NADH and CO₂, forms **4-C
6. 4-C undergoes several reactions, forms 1 ATP, 1 FADH2, and 1 NADH, and continues to beginning of cycle, bonding with incoming acetyl-CoA

Question 24

What is consumed and what is produced by the krebs cycle, including the intermediate step, for each pyruvate that goes into it?

Answer 24

Consumed

• 1 H₂0

Produced

• 4 NADH
• 1 FADH₂
• 1 ATP
• 3 CO₂

Question 25

What are the major steps of the electron transport chain?

Answer 25

1. **NADH and FADH₂** from C.A. cycle **release H⁺ and e^- into** the intramembranal proteins of the **ETC** 2. **H⁺ is concentrated in the intermembranal space** of the mitochondria 3. Concentrated **H⁺ flows back into** the mitochondrial **matrix via ATP Synthase**, which it activates, **creating ATP via** oxidative phosphorylation 4. **H⁺** back in matrix **combines with spent e^-** from the ETC **and O₂ to form H₂0**

Question 26

What is consumed and what is produced by the ETC and oxidative phosphorylation (per glucose molecule)?

Answer 26

**_Consumed:_** - 10 NADH - 2 FADH2 **_Produced:_** - 28 ATP (*10 NADH x 2.5 ATP* + *2 FADH2 x 1.5 ATP*) - 6 H₂0

Question 27

What is the overall reaction for respiration?

Answer 27

C6H12O6 + O2 ------\> 6CO2 + 6 H2O + energy (ATP)

Question 28

Compare substrate-level and oxidative phosphorylation.

Answer 28

***_Substrate-level phosphorylation:_*** - does not consume oxygen - takes place in glycolysis and the kreb cycle **_Oxidative phosphorylation:_** - consumes oxygen - takes plave in the ETC on the cristae membrane of mitochondria

Question 29

How and where is ATP produced via glucose metabolism?

Answer 29

- in all three steps of respiration

Question 30

How and where is ATP produced via lipid metabolism?

Answer 30

- triglycerides are broken down into glycerol and fatty acid chains by lipase - 3-C glycerol molecules enter glycolysis at the same point where C-C-C-P molecules start after sugar cleavage - F.A. chains are broken up in to 2-C fragments via **beta oxidation** and enter the Krebs cycle as C-C-CoA (Acetyl CoA) ( 15-16 ATP per glycerol, b/c it's equal to half a glucose each 2-C F.A. chain fragment runs through Krebs once, creating 3 NADH, 1 FADH2 and 1 ATP)

Question 31

How and where is ATP produced via protein metabolism?

Answer 31

- liver removes amine group from fatty acids via **oxidative deamination** - leftover multicarbon acid goes to respiration for ATP production