Chapter 6: How Cells Utilize Energy

Question 1

What is the function of catabolic reactions?

Ch 6.3

Answer 1

Break down of larger molecules into smaller ones (EXERGONIC)

Ch 6.3

Question 2

What is the function of anabolic reactions?

Ch 6.3

Answer 2

Synthesis/Building of larger molecules from smaller ones (ENDERGONIC)

Ch 6.3

Question 3

How do catabolic reactions create ATP ?

Ch 6.3

Answer 3

By recycling organic molecules

Ch 6.3

Question 4

What is the removal of electrons called ?

Ch 6.3

Answer 4

Oxidation Reaction

Ch 6.3

Question 5

What is it called when an electron of one molecule is transferred to another?

Ch 6.3

Answer 5

Reduction-Oxidation (REDOX) Reactions

Ch 6.3

Question 6

What is the reaction where electrons are added ?

Ch 6.3

Answer 6

Reduction Reaction

Ch 6.3

Question 7

TRUE or FALSE: Oxidation reactions has more energy stored within its cellular bonds than reduction reactions

Ch 6.3

Answer 7

FALSE; Oxidation reactions have less energy within their cellular bonds in comparison to reduction reactions

Ch 6.3

Question 8

What is the function of NAD+/NADH in redox reactions?

Ch 6.3

Answer 8

Break down of “food” molecules

example: glucose & fat molecules

Ch 6.3

Question 9

What are the 3 ways Metabolic Pathways are regulated ?

Ch 6.3

Answer 9

GENETIC, CELLULAR, BIOCHEMICAL

Ch 6.3

Question 10

Define genetic metabolic pathway regulation.

Ch 6.3

Answer 10

Gene regulation; increase or decrease in gene expression

Ch 6.3

Question 11

Define cellular metabolic pathway regulation.

Ch 6.3

Answer 11

Cells integrate signals from their environment and adjust metabolic activity accordingly

Question 12

Define biochemical metabolic pathway regulation.

Ch 6.3

Answer 12

Feedback inhibition; a product of a pathway binds a pathway enxyme at an allosteric site and decreases production of enzymes as needed

Allosteric Site: Where molecules are allowed to start/stop enzyme activity

Question 13

Which is oxidated and which is reduced?

Ae- + B → A + Be-

Ch 6.3

Answer 13

A is Oxidated, B is Reduced

Oxidated: Electron Removal ; Reduction: Addition of Electron

Question 14

Define Cellular Respiration

Ch 6.4

Answer 14

The process in which living cells obtain energy from organic molecules to make ATP

Question 15

What’s the difference between kinetic and potential energy?

Ch 6.1

Answer 15

kinetic energy is associated with movement (such as a baseball bat from one location to another) , while potential energy is the energy that is stored in an object or substance (such as the location of an arrow when a bow is drawn).

Question 16

What is the first law of thermodynamics?

Ch 6.1

Answer 16

Energy cannot be created or destroyed.

Question 17

What is the second law of thermodynamics?

Ch 6.1

Answer 17

Any energy transformation from one form to another increases the degree of disorder of a system, which is called entropy.

Question 18

Describe the relationship between entropy and energy disorder.

Ch 6.1

Answer 18

If an energy system is more disordered, entropy increases. As energy becomes evenly distributed, the energy is less ale to promote change.

Question 19

Which do you think has more entropy, a NaCl crystal at the bottom of a beaker of water, or the solution that would be formed after the Na+ and Cl forming the crystal have dissolved in the water?

Ch 6.1

Answer 19

The solution has more entropy because a salt crystal is very ordered whereas the ions in the solution would be much more disordered.

Question 20

T or F: Entropy is a main component of usable energy.

Ch 6.1

Answer 20

FALSE: entropy is a main component of UNUSABLE energy

Question 21

Describe what exergonic reactions are. What are some characteristics of an exergonic reaction?

Ch 6.1

Answer 21

If a chemical reaction has a NEGATIVE free-energy change, then the products have LESS free energy than the reactants, and therefore free energy is RELEASED during product formation. It IS spontaneous; meaning it is slow and occurs on its own.

Question 22

Describe endergonic reactions. What are some characteristics of endergonic reactions?

Ch 6.1

Answer 22

When a chemical has a POSITIVE free energy change, and it requires the ADDITION of free energy. It is NOT a spontaneous reaction.

Question 23

Most reactions that cells must accomplish are _________. In order for them to overcome this problem, one strategy is to couple ________ reactions with them. If they are coupled together, the __________ reaction will proceed spontaneously.

Ch 6.1

Answer 23

1) endergonic
2) exergonic
3) endergonic

Question 24

Identify which image is endergonic and which one is exergonic.

Ch 6.1

Answer 24

Left: exergonic
Right: endergonic

Question 25

The hydrolysis of ATP is an example of an ____________ reaction. The energy released from ATP hydrolysis is used to drive other ___________ reactions. ##Footnote Ch 6.1

Answer 25

1) exergonic 2) endergonic

Question 26

T or F: A spontaneous reaction is a fast reaction. ##Footnote Ch 6.2

Answer 26

FALSE: Not necessarily.

Question 27

Define activation energy. ##Footnote Ch 6.2

Answer 27

input of energy in a chemical reaction that allows molecules to cause a rearrangement of bonds.

Question 28

This is an image of the steps of an enzyme catalyzed reaction. The example here shown involves the enzyme hexokinase, which binds ATP and glucose. The products are glucose-6-phosphate and ADP. Briefly describe each step. ##Footnote Ch 6.2

Answer 28

1) substrates (ATP and glucose) bind to the enzyme (hexokinase) 2) enzyme undergoes conformational change, binding the substrates more tightly 3) substrates are converted to products 4) products (ADP and glucose-6-phosphate) are released, and enzyme is ready to be reused! :D

Question 29

During which step is the activation energy lowered? ##Footnote Ch 6.2

Answer 29

Step 2 when the substrates undergo induced fit.

Question 30

Define affinity. ##Footnote Ch 6.2

Answer 30

The attraction of an enzyme for a substrate.

Question 31

Define Vmax and Km. ##Footnote Ch 6.2

Answer 31

Vmax is the maximal rate of a reaction. Km is the substrate concentration where velocity is half the max.

Question 32

Define and compare competitive and noncompetitive inhibitors. ##Footnote Ch 6.2

Answer 32

Competitive inhibitors raise Km for the substrate without affecting the Vmax; bind noncovalently to the active site which compete with the substrate in binding to the enzyme Noncompetitive inhibitors lower the Vmax for the reaction without affecting the Km; binds noncovalently to an enzyme at a location outside the active site, called an allosteric site.

Question 33

What factors influence enzyme structure and function? What are the optimal requirements in order for enzymes to properly function? ##Footnote Ch 6.2

Answer 33

1) Temperature, pH, and ionic conditions. 2) Optimal temp is 37 degrees celsius or 98.6 degrees Fahrenheit. For pH, it depends on the type of enzyme.

Question 34

What are the two general functions of catabolic pathways? ##Footnote Ch 6.3

Answer 34

1) to recycle the components of organic molecules 2) to obtain energy for use in endergonic reactions

Question 35

What is chemical energy? ##Footnote Ch 6.1

Answer 35

A form of potential energy stored in chemical bonds.

Question 36

Define aerobic respiration. ##Footnote Ch 6.4

Answer 36

A type of cellular respiration in which O2 (oxygen) is consumed and CO2 (carbon dioxide) is released.

Question 37

When glucose is broken down via oxidation, __________ is released, but some of this energy is lost as _____. However, most of this energy is used to make 3 energy intermediates: _____, _____, and ________. ##Footnote Ch 6.4

Answer 37

1) free energy 2) heat 3) ATP, NADH, FADH2

Question 38

Cellular respiration is a process that involves four metabolic pathways: glycolysis, pyruvate breakdown, the citric acid cycle and oxidative phosphorylation. Which of these processes does NOT produce ATP? ##Footnote Ch 6.4

Answer 38

the breakdown of pyruvate

Question 39

Define glycolysis. *Bonus: Draw it* ##Footnote Ch 6.5

Answer 39

Glycolysis involves the breakdown of glucose, a simple sugar, into two molecules of a compound called pyruvate.

Question 40

What are the 3 phases of glycolysis? ##Footnote Ch 6.5

Answer 40

energy investment phase, cleavage phase, and the energy liberation phase

Question 41

During glycolysis, ATP is used during the ______ phase, and ATP is synthesized during the ______ phase. ##Footnote Ch 6.5

Answer 41

energy investment; energy liberation

Question 42

T or F: ATP, NADH, and pyruvate are products of glycolysis, while CO2 is NOT a product of glycolysis.

Answer 42

True :D

Question 43

What is the chemical composition like during glycolysis? That is…what is being transformed, and what is being produced? ##Footnote Ch 6.5

Answer 43

Overall, 1 molecule of glucose is transformed into 2 molecules of pyruvate, and a net of 2 ATP and 2 NADH are generated

Question 44

Where is glycolysis located in the cell? ##Footnote Ch 6.5

Answer 44

the cytoplasm

Question 45

Where is the breakdown of pyruvate located in the cell? ##Footnote Ch 6.6

Answer 45

Glycolysis produces pyruvate in the cytosol, then is transported into the mitochondrial matrix

Question 46

What molecule is removed from pyruvate? ##Footnote Ch 6.6

Answer 46

CO2 (carbon dioxide)

Question 47

T or F: Pyruvate is oxidized by an enzyme complex called pyruvate dehydrogenase. ##Footnote Ch 6.6

Answer 47

True :D

Question 48

What is the chemical composition like during the breakdown of pyruvate? What is being transformed and what is being produced? ##Footnote Ch 6.6

Answer 48

a molecule of CO2 is removed, then the remaining acetyl group is attach to an organic molecule called coenzyme A (CoA) and then acetyl CoA is produced. 1 NADH is produced for each pyruvate.

Question 49

T or F: ATP, NADH, acetyl group attach to CoA, and CO2 are ALL products of the breakdown of pyruvate. ##Footnote Ch 6.6

Answer 49

FALSE; ATP is NOT a product of the breakdown of pyruvate

Question 50

What are the products of the citric acid cycle? ##Footnote Ch 6.7

Answer 50

4 CO2, 6 NADH, 2 FADH2, GTP and CoA

Question 51

Briefly explain what happens during the citric acid cycle. ##Footnote Ch 6.7

Answer 51

An acetyl group is removed from acetyl CoA and attached to oxaloacetate to make citrate. Then, 4 CO2 molecules, 6 NADH, 2 FADH2 and 2 ATP are made. Then the cycle begins again.

Question 52

During the citric acid cycle, what happens to carbon? ##Footnote Ch 6.7

Answer 52

carbon is oxidized to make NADH and FADH2.

Question 53

During the first 3 stages of glucose metabolism, the oxidation of glucose yields __ molecules of CO2, __ molecules of ATP, __ molecules of NADH, and __ molecules of FADH2. ##Footnote Ch 6.8

Answer 53

6; 4; 10; 2

Question 54

Define oxidative phosphorylation. ##Footnote Ch 6.8

Answer 54

The process in which NADH and FADH2 have electrons removed and become oxidized to generate a H+ gradient

Question 55

Where does oxidative phosphorylation occur in the cell? ##Footnote Ch 6.8

Answer 55

electron transport chain (ETC) inside the mitochondrial matrix

Question 56

At the end of the chain is _______, which is the most electronegative component and the final electron acceptor. ##Footnote Ch 6.8

Answer 56

oxygen

Question 57

What are the reasons that the maximum amount of ATP may not always be produced through oxidative phosphorylation? ##Footnote Ch 6.8

Answer 57

some NADH might be used to synthesize organic molecules AND the mitochondria may use some of the H+ gradient for other purposes

Question 58

What are the two distinct events that occur in oxidative phosphorylation? ##Footnote Ch 6.8

Answer 58

1) electron transport chain and 2) ATP synthesis

Question 59

At the end of oxidative phosphorylation, about how much ATP can be synthesized? How much is USUALLY synthesized? ##Footnote Ch 6.8

Answer 59

1) 30-34 ATP 2) less than 25, which is still greater than the amount that is generated in glycolysis or the citric acid cycle

Question 60

Why do cells rarely achieve the maximal amount of ATP? ##Footnote Ch 6.8

Answer 60

1) NDH is also used in anabolic pathways 2) H+ gradient is also used for other purposes

Question 61

The source of energy that directly drives the synthesis of ATP during oxidative phosphorylation is _______ ##Footnote Ch 6.8

Answer 61

the H+ gradient

Question 62

Fatty acid tails have _______ acetyl units removed, which bind to _____ and enter the citric acid cycle. ##Footnote Ch 6.9

Answer 62

two-carbon; CoA

Question 63

The advantage of connecting metabolic pathways for carbohydrate, protein, and fat metabolism is that ________________. ##Footnote Ch 6.9

Answer 63

the same enzymes are used to break down different starting materials

Question 64

Define anaerobic. ##Footnote Ch 6.10

Answer 64

the term is used to describe an environment that lacks oxygen

Question 65

What are the 2 mechanisms that have allowed organic molecules WITHOUT oxygen? ##Footnote Ch 6.10

Answer 65

1) anaerobic respiration 2) fermentation

Question 66

One strategy to produce ATP under anaerobic conditions is to make ATP only via _________. ##Footnote Ch 6.10

Answer 66

glycolysis

Question 67

Under anaerobic conditions, _______ builds up and _______ decreases. ##Footnote Ch 6.10

Answer 67

1) NADH 2) NAD+

Question 68

What are some examples of fermentation processes that oxidize NADH to NAD+ (that allow glycolysis to continue)? ##Footnote Ch 6.10

Answer 68

lactic acid production in muscle and ethanol production in yeast

Question 69

Define fermentation. ##Footnote Ch 6.10

Answer 69

the breakdown of organic molecules without net oxidation