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601 - Exam 1 > 2.3 TCA, ETC, PDH > Flashcards

2.3 TCA, ETC, PDH Flashcards

1
Q

PDH function

A

Converts pyruvate to acetyl-CoA

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2
Q

Where do PDH and TCA occur?

A

Mitochondrial matrix

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3
Q

Where does the ETC occur?

A

Mitochondrial inner membrane

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4
Q

Function of TCA cycle

A

To oxidize acetyl CoA to Co2

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5
Q

TCA is the final common oxidative pathway for ___

A

Carbohydrates, fats, and amino acids

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6
Q

All of the TCA enzymes are soluble, except for

A

Succinate dehydrogenase

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7
Q

Does the TCA cycle directly consume oxygen?

A

No

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8
Q

How can vitamin deficiencies affect the TCA cycle?

A

Vitamins act as a cofactor for enzymes, so a deficiency in them causes reduced activity of enzymes resulting in lactic acidosis and neurological defects

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9
Q

Is the TCA a closed or open loop cycle?

A

Closed

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10
Q

Why is the TCA cycle considered an aerobic pathway?

A

B/c the NADH and FADH2 produced must transfer electrons to the ETC, which needs oxygen

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11
Q

End products of TCA cycle

A

6 NADH
2 GTP
(b/c cycle turns twice)

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12
Q

TCA cycle is a source of ___

A 
Biosynthetic precursors
(important source for other building blocks in the cell)
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13
Q

Steps of TCA cycle

A
  1. Acetyl-CoA + oxaloacetate + citrate synthase = citrate
  2. Citrate + aconitase = Isocitrate
  3. Isocitrate + isocitrate dehydrogenase = alpha-Ketoglutarate
  4. Alpha-ketoglutarate + alpha-ketoglutarate dehydrogenase complex = succinyl-CoA
  5. Succinyl-CoA + syccinyl-CoA synthetase = Succinate
  6. Succinate + succinate dehydrogenase = fumarate
  7. Fumarate + fumarase = malate
  8. Malate + malate dehydrogenase = oxaloacetate
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14
Q

In which steps of the TCA cycle is CO2 released?

A

Decarboxylation of isocitrate to alpha-ketoglutarate

Decarboxylation of alpha-ketoglutarate to succinyl-CoA

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15
Q

Which step in the TCA cycle is GTP released?

A

Conversion of succinyl-CoA to Succinate through substrate level phosphorylation

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16
Q

What steps of the TCA cycle is NADH released?

A

Conversion of isocitrate to alpha-ketoglutarate
Conversion of alpha-ketoglutarate to succinyl-CoA
Conversion of malate to oxaloacetate

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17
Q

What step of the TCA is FADH2 released?

A

Conversion of succinate to fumarate

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18
Q

What’s significant about FADH2 when it’s released?

A

2 electrons immediately go to the ETC

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19
Q

What enzymes regulate the TCA cycle?

A

Citrate synthesis
Isocitrate dehydrogenase
alpha-ketoglutarate dehydrogenase

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20
Q

Electrons donated by NADH and FADH2 flow through the ___, causing protons to be pumped from the matrix to the intermembrane space

A

ETC

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21
Q

The ___ in the ETC are passed to ___, which combines with protons to form water

A

Electrons

Oxygen

22
Q

The protons form a concentration gradient in the ETC, which power the ___

A

Catalytic action of ATP synthase

23
Q

Where do H+ ions build up in in the ETC

A

intermembrane space

24
Q

The ETC and ATP synthase process is called

A

Oxidative phosphorylation

25
Q

What are the 2 electron carriers in the ETC?

A

Coenzyme Q and cytochrome C

26
Q

Complex 1 in ETC is called and what does it do?

A

NADH dehydrogenase
accepts electrons from NADH and transfers them to coenzyme Q

NADH + H+ = NAD+

27
Q

Complex II in the ETC is called what and what’s its function

A

Succinate dehydrogenase
Accepts e- from FADH2 and transfers them to Coenzyme Q

NOT a proton pump

28
Q

Name of complex III in ETC and what’s its function

A

Ubiquinone-Cytochrome C Reductase/Cytochrome Reductase

Accepts e- from coenzyme Q and transfers them to cytochrome C

29
Q

Name of complex IV and what’s its function?

A

Cytochrome oxidase
Accepts e- from cytochrome C to reduce oxygen to H2O
Also known as a proton pump

30
Q

What’s the sequence of e- passage in the ETC?

A 
From complex I or II to Coenzyme Q
From Coenzyme Q to complex III
From complex III to cytochrome C
From cytochrome C to complex IV
From complex IV to oxygen (to form H2O)
31
Q

Describe ATP synthase

A

Also called complex V (5)

Made of 2 parts: F0 in the inner mitochondrial membrane and F1 in the mitochondrial matrix

3-4 protons move through this machine to convert a molecule of ADP and Pi to ATP

32
Q

The synthesis of ATP is brought about by the ___

A

Rotary motion

  • Large electrochemical potential flows through F0 subunit and causes a rotation, and subsequently F1 leading to ATP synthesis
  • The mechanical energy is converted into chemical energy
33
Q

What do inhibitors of the ETC result in?

A

Decreased O2 consumption
Increased intracellular NADH/NAD+ and FADH2/FAD ratio
Decreased ATP

34
Q

What does cyanide do?

A

Acts as an irreversible enzyme inhibitor of cytochrome C oxidase (complex IV)
- Stops oxidative phosphorylation and ATP production

35
Q

What does Oligomycin do?

A

It’s an ATP synthase inhibitor

  • It blocks Fo subunit and prevents reentry of protons into the matrix and prevents phosphorylation of ADP to ATP
  • H+ ions stay in the inner membrane space
36
Q

What are the types of uncouplers of oxidative phosphorylation?

A

Drugs (uncouplers) and proteins (uncoupling proteins)

37
Q

What do uncouplers of oxidative phosphorylation do?

A

Inhibit phosphorylation of ADP

38
Q

Describe dinitrophenol (DNP)

A

Acts as a protonophore
- Allows protons to leak across the inner mitochondrial membrane and bypass ATP synthase

Used as a weight loss
Generates a lot of heat

39
Q

___ protein is an inner mitochondrial membrane protein found in brown adipose tissue and present in newborn babies

A

Uncoupling protein

40
Q

Describe metformin

A

A prescription drug used to treat type 2 diabetes

Inhibits complex I

41
Q

Describe the pyruvate dehydrogenase (PDH) complex

A

Connects the TCA cycle and subsequent oxidative phosphorylation to glycolysis

42
Q

Where is PDH located?

A

Mitochondria

43
Q

Net result of pyruvate to acetyl-CoA

A

2 NADH and 5 ATP

44
Q

Pyruvate loses ___ when converting to acetyl-CoA

A

Co2

45
Q

What are the enzymes associated with PDH?

A 
Pyruvate dehydrogenase (E1)
Dihydrolipoyl transacetylase (E2)
Dihydrolipoyl dehydrogenase (E3)
46
Q

What are the coenzymes associated with PDH?

A 
TPP
Lipoic Acid
FAD
NAD+
CoASH
47
Q

PDH coenzymes are derived from ___

A

Vitamins

48
Q

alpha-Ketoglutarate dehydrogenase (KDH) is structurally similar to ___

A

PDH

49
Q

What happens when there is a high and low energy charge in the PDH?

A

High energy = slows down glycolysis and conversion of pyruvate to acetyl-CoA

Low energy = speeds up reaction and activates PDH

50
Q

Phosphorylation of PDH is mediated by ___

A

Pyruvate dehydrogenase kinase (PDHK)

51
Q

What enzyme in PDH is activated by insulin?

A

PDH phosphatase

52
Q

What enzyme is activated by glucagon and wants to inhibit PDH reaction?

A

PDH kinase

It pulls off ATP

601 - Exam 1 (10 decks)

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