Biochemistry Chapter 8: Aerobic Carbohydrate Metabolism

Question 1

What do diabetic patients rely on for metabolism if in a state of extended hyperglycemia?

Answer 1

Fat metabolism. Therefore, ketones will be found in the urine

Question 2

Dysglycemia

Answer 2

refers to abnormal blood glucose levels, encompassing both hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar), often associated with conditions like diabetes or metabolic syndrome.

Question 3

True or false: GLUT2 transport protein is expressed primarily in the liver and pancreas. Therefore, GLUT2 deficiency would result in stunted growth.

Answer 3

TRUE. The signaling required for glucose metabolism would be unable to effectively provide glucose to growing tissues, and glycogen stored in the liver could not be effectively released to tissues, so avoiding significant complications for a growing child would require the strictest possible dietary monitoring

Question 4

Cyanide poisoning is the result of an impaired

Answer 4

ETC function

Question 5

Substrate level phosphorylation

Answer 5

Add phosphate group to derivative of glucose and then add ADP

Question 6

Oxidative Phosphorlaytion

Answer 6

NADH FADH2 etc are oxidized to create a proton gradient and then pumped back through ATP synthase to catalyze phosphorlyation of ADP into ATP

Question 7

ETC requires oxygen _______ whereas krebs cycle require oxygen _________

Answer 7

Directly, indirectly

Question 8

Goal of the Krebs Cycle

Answer 8

is to generate high-energy electron carriers (NADH and FADH₂) and intermediates for ATP production, which fuel the process of oxidative phosphorylation in cellular respiration

Question 9

Location of Krebs Cycle

Answer 9

In eukaryotes, mitochondrial matrix

Question 10

Pyruvate dehydrogenase complex (PDC)

Answer 10

converts pyruvate to acetyl-CoA before entering citric acid cycle → 1 NADH generated.

Question 11

Net products of Critic Acid Cycle per turn

Answer 11

1 GTP, 3 NADH, 1 FADH₂, 2 CO₂.

Question 12

Stoichiometry: each glucose molecule = how many turns of the TCA?

Answer 12

2 turns of citric acid cycle.

Question 13

Citric Acid cycle is a metabolic crossroads in the body because

Answer 13

Byproducts of other molecules (lipids, proteins) can enter into citric acid cycle, and intermediates of citric acid cycle are precursors for other metabolic processes

Question 14

Start of citric acid cycle

Answer 14

acetyl-CoA (2C) + oxaloacetate (4C) → citrate (6C)

Question 15

Step 3 citric acid cycle

Answer 15

isocitrate (6C) → α-ketoglutarate (5C)

Question 16

Step 4 citric acid cycle

Answer 16

α-ketoglutarate (5C) → succinyl-CoA (4C)

Question 17

Principle of ETC

Answer 17

electrons transferred along series of carriers, moving from carriers with lower reduction potentials to those with higher reduction potentials

Question 18

ETC is like what kind of electrochemical cell

Answer 18

similarly to a galvanic cell

Question 19

Energy from ETC

Answer 19

pumps protons into intermembrane space, creating proton gradient

Question 20

Electron transfer in the ETC involves what structures?

Answer 20

Complexes I, II, III, IV are embedded in inner mitochondrial membrane, and together with electron carriers Q and cytochrome c are used in electron transfer

Question 21

Final electron acceptor in ETC

Answer 21

Oxygen is the final electron acceptor in the ETC and is reduced to H₂O.

Question 22

Electrochemical energy of proton gradient is used to power

Answer 22

is used to power ATP synthase, which attaches a phosphate group to ADP to form ATP.

Question 23

↑ATP, ↑products of citric acid cycle =

Answer 23

↓citric acid cycle

Question 24

↑ADP (showing that cell needs energy)

Answer 24

↑citric acid cycle

Question 25

↑ADP = ____ oxidative phosphorylation

Answer 25

↑ETC/oxidative phosphorylation.

Question 26

electron transport chain (ETC) takes place

Answer 26

across the inner mitochondrial membrane, specifically between the mitochondrial matrix and the intermembrane space

Question 27

goal of the electron transport chain

Answer 27

To generate a proton gradient (H⁺ gradient) across the inner mitochondrial membrane, which drives the synthesis of ATP

Question 28

Input and Output of Krebs Cycle (per 1 turn)

Answer 28

Input: 1) Acetyl-CoA (2-carbon molecule): Derived from pyruvate via the pyruvate dehydrogenase complex. 2) Oxaloacetate (4-carbon molecule): Combines with acetyl-CoA to form citrate. 3) 3 NAD⁺: Electron carrier that gets reduced to NADH. 4) 1 FAD: Electron carrier that gets reduced to FADH₂. 5) 1 GDP (or ADP): Used to form GTP (or ATP) via substrate-level phosphorylation. 6) 2 H₂O: Water molecules used in enzymatic reactions during the cycle. Output: 1) 2 CO₂: Released as byproducts of acetyl-CoA oxidation. 2) 3 NADH: High-energy electron carrier for the electron transport chain. 3) 1 FADH₂: High-energy electron carrier for the electron transport chain. 4) 1 GTP (or ATP): Usable energy via substrate-level phosphorylation. 5) Oxaloacetate: Regenerated to combine with another acetyl-CoA for the next cycle.

Question 29

Net Inputs and Outputs for 1 Glucose

Answer 29

Since 1 glucose molecule produces 2 acetyl-CoA molecules, the Krebs cycle runs twice per glucose Inputs (2 Turns of Krebs Cycle for 1 Glucose): 2 Acetyl-CoA 6 NAD⁺ 2 FAD 2 GDP (or ADP) 4 H₂O Outputs (2 Turns of Krebs Cycle for 1 Glucose): 4 CO₂ 6 NADH 2 FADH₂ 2 GTP (or ATP) 2 Oxaloacetate (regenerated)

Question 30

ATP per NADH

Answer 30

2.5 molecules

Question 31

ATP per FADH2

Answer 31

1.5

Question 32

Grand Total ATP Yield per Glucose

Answer 32

Question 33

pyruvate decarboxylation produces

Answer 33

acetyl CoA for the Citric Acid Cycle

Question 34

The electron carriers in the ETC can transport a maximum of ____ electrons

Answer 34

1 - 2

Question 35

UTP tags glucose for what

Answer 35

Glycogen synthesis

Question 36

ATP consists of three phosphate groups:

Answer 36

ATP consists of three phosphate groups: α-phosphate (alpha) – directly attached to the ribose sugar. β-phosphate (beta) – middle phosphate. γ-phosphate (gamma) – outermost phosphate.

Question 37

Can Glutamate be used in the krebs cycle?

Answer 37

Yes, Glutamate is converted into α-ketoglutarate, which enters the Krebs cycle (TCA cycle) to generate ATP.

Question 38

Complex I ETC name

Answer 38

NADH: ubiquinone oxidoreductase

Question 39

Complex 2 ETC name

Answer 39

succinate dehydrogenase

Question 40

Complex III ETC name

Answer 40

Ubiquinol–cytochrome c oxidoreductase

Question 41

Complex IV ETC name

Answer 41

cytochrome c oxidase

Question 42

How is ATP electrophilic even though it has a negative charge?

Answer 42

Despite being negatively charged, the phosphorus atom in ATP’s phosphate groups is still electron-deficient due to electronegative oxygen atoms pulling electron density away. Electrostatic strain from negative charges makes ATP's γ-phosphate highly reactive. Magnesium ions (Mg²⁺) help stabilize negative charge, further increasing ATP’s electrophilicity. Resonance stabilization in phosphate groups makes ATP hydrolysis favorable, encouraging nucleophilic attack.

Question 43

End result of the Conversion of 1 pyruvate to Acetyl-CoA

Answer 43

1 NADH is produced 1 CO₂ is released 1 Acetyl-CoA is formed