BIOENERGETICS

Question 1

• Measure of change in heat content of the reactants and products
• Measured in joules (J)

Answer 1

CHANGE IN ENTHALPY (ΔH)

Question 2

• Measure of the change in randomness or disorder of the reactants and producs
• Measured in joules/Kelvin (J/K)

Answer 2

CHANGE IN ENTROPY (ΔS)

Question 3

• Net loss of energy (Exergonic)

IS REACTION SPONTANEOUS?

Answer 3

YES (ΔG < 0)

Question 4

• Net gain of energy (Endergonic)

IS REACTION SPONTANEOUS?

Answer 4

NO

Question 5

What are the 4 compounts that yields more Free energy than ATP?

Answer 5

“PC1C”

• Phosphoenolpyruvate
• Carbamoyl phosphate
• 1, 3 bisphosphoglycerate
• Creatine phosphate

Question 6

What are the 2 mechanisms by which ATP is produced?

Answer 6

1. SUBSTRATE LEVEL PHOSPHORYLATION
2. OXIDATIVE PHOSPHORYLATION

Question 7

2 examples of processes where high energy phosphate is generated for substrate level phosphorylation.

Answer 7

• Glycolysis
  
  • Net formation of two high energy phosphates results from the formation of lactate from one molecule of glucose, generated in two reactions catalyzed by phosphoglycerate kinase and pyruvate kinase
• Citric acid cycle
  
  • One high energy phosphate is generated directly at the succinyl thiokinase step

Question 8

Where does SUBSTRATE LEVEL PHOSPHORYLATION occur?

Answer 8

Cytosol OR mitochondria

Question 9

Substrate level phosphorylation requires O2 and mitochondria. True or false.

Answer 9

False

Question 10

REquirements for OXIDATIVE PHOSPHORYLATION.

Answer 10

O2 and MITOCHONDRIA (should have both)

Question 11

OXIDATIVE PHOSPHORYLATION occurs ONLY in what part of the cell?

Answer 11

MITOCHONDRIA

Question 12

ETC is located where?

Answer 12

Inner membrane of the mitochondria

Question 13

•What are the 2 electron carriers used in the ETC?

Answer 13

o Nicotinamide Adenine Dinucleotide (NAD+)

o Flavin Adenine Dinucleotide (FAD)

Question 14

NADH = Derived from _____

FADH2 = Derived from _____

Answer 14

NADH = Derived from niacin (Vitamin B 3 )

FADH2 = Derived from riboflavin (Vitamin B 2 )

Question 15

the only non-protein component of the ETC

Answer 15

• Ubiquinone (CoQ)

Question 16

Protons (H + ) are pumped to the intermembranous space in what complexes of the ETC?

Answer 16

3 complexes (I, III, and IV)

Question 17

Final electron acceptor in ETC?

Answer 17

oxygen (O 2 )

Question 18

Discuss ETC

Answer 18

Question 19

What will happen to ATP production if there is tissue hypoxia?

Answer 19

• When there is lack of O 2 , there is decreased activity of the electron transport chain
• ATP production shifts from oxidative phosphorylation to substrate-level phosphorylation
  
  • Substrate-level phosphorylation does not require oxygen, but anaerobic glycolysis is not enough for highly aerobic tissues like neurons and cardiac muscle

Question 20

What are the effects of ETC INHIBITORS?

Answer 20

• ↓ oxygen consumption
• Decrease ATP
• ↑ intracellular NADH/NAD + and FADH 2 /FAD ratios
  
  • NADH and FADH 2 accumulate because they cannot transfer electrons to the ETC

Question 21

Examples of Complex I inhibitors.

NADH dehydrogenase (NADH:CoQ oxidoreductase)

Answer 21

“BARP”

• Barbiturates
• Amytal
• Rotenone
• Piericidin A

Question 22

Complex II inhibitors.

Succinate dehydrogenase

Answer 22

“2 MaCaT (Makati)”

• Malonate
• Carboxin
• TTFA (Thenoyltrifluoroacetone)

Question 23

Complex III inhibitors

Cytochrome b-c1 complex (CoQ:c1 oxidoreductase)

Answer 23

“3 AnDi”

• Antimycin A
• Dimercaprol

Question 24

Complex IV inhibitors

Cytochrome c oxidase

Answer 24

“SHyCC”

• Sodium Azide
• Hydrogen Sulfide

• Cyanide

• Carbon monoxide

Question 25

Inhibits oxidative phosphorylation by inhibiting the transporter of ADP into and ATP out of the mitochondrion.

Answer 25

ATRACTYLOSIDE

* ayaw nya papasukin yung ADP, ayaw rin nya palabasin yung ATP sa mitochondria

Question 26

These are Compounds in the ETC that increase the permeability of the inner mitochondrial membrane to protons

Answer 26

UNCOUPLERS

Question 27

What are the effects of ETC uncouplers?

Answer 27

o ↑ oxygen consumption

o ↓ NADH/NAD+ and FADH2/FADH ratio

o ↓ ATP synthesis

Question 28

Examples of ETC uncouplers

Answer 28

o Synthetic: 2,4 dinitrophenol, aspirin

o Uncoupling protein: Thermogenin (brown fat)

Question 29

Give examples of ATP SYNTHASE INHIBITORS

• Directly inhibit ATP Synthase (complex V)
• Proton gradient continues to rise but there is no “escape valve” for the protons
• ETC eventually stops because the cytochromes can no longer pump protons into the intermembranous space

Answer 29

Oligomycin

Oligomycin blocks F 0 subunit of ATP synthase

Question 30

Examples of mitochondrial diseases

Answer 30

• Mitochondrial Encephalomyelopathy, Lactic Acidosis, and Stroke-like episodes (MELAS)
  
  • encephalomyopathy clinically characterized by short stature, stroke-like episodes, migrainous headaches, vomiting, seizures, and lactic acidosis
  • § between age 5 and 15 years
• Leber Hereditary Optic Neuropathy (LHON)
  
  • point mutations in mitochondrial DNA result to loss of retinal ganglion cell, leading to late onset acute optic neuropathy and bilateral central vision loss
  • majority from mutation in NADH dehydrogenase

Question 31

Unstable products that are formed as a byproduct of the ETC, when molecular oxygen (O2 ) is partially reduced:

Answer 31

o superoxide (∙O2 - )

o hydrogen peroxide (H2O2)

o hydroxyl radical (OH∙)

Question 32

What are the Defenses against ROS accumulation?

Answer 32