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Bio Chem 2 > 2nd Midterm > Flashcards

2nd Midterm Flashcards

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1
Q

What are the products of the PDH reaction?

A

Acetyl CoA, CO2, and NADH

56

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2
Q

What does the coenzyme Thiamine pyrophosphate (TPP) do in the PHD reaction?

A

Reacts w/ pyruvate

57

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3
Q

What does the coenzyme Lipoic acid do in the PDH reaction?

A

Transfers Acetyl group to CoA

57

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4
Q

What does Coenzyme A do in the PDH reaction?

A

Accepts acetyl group

57

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5
Q

What does the coenzyme FAD do in the PDH reaction?

A

Regenerates lipoic acid

57

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6
Q

True or False: The citric acid cycle (Kreb’s cycle) is amphibolic?
(=both anabolic and catabolic)

A

True (59)

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7
Q

What are the 4 major steps in the Krebs Cycle?

A 
Condensation
NADH, FADH2 formation
Decarboxylations 
GTP formation 
(59)
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8
Q

Which half of the Krebs Cycle regenerates Oxaloacetate?

Which half produces CO2?

A

1st half produces CO2
2nd half regenerates OA
(60)

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9
Q

What are the products of the Krebs Cycle?

A

2 CO2
3 NADH
1 FADH2
(60)

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10
Q

Describe the Condensation step in the Krebs Cycle?

A

Oxaloacetate (4 carbon) + Acetyl-CoA (2 carbon) = Citrate (6 carbon)
(61)

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11
Q

Is GTP formation in the Krebs cycle Oxidative Phosphorylation or Substrate Level Phosphorylation?

A

Substrate level phosphorylation

62

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12
Q

True or False: Increased ATP/ADP ratio will decrease citrate synthase activity?

A

True

62

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13
Q

True or False: Increased NADH/NAD ratio will increase isocitrate dehydrogenase activity?

A

False
Decreases this enzymes activity
(62)

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14
Q

True or False: Adding intermediates or removing Oxaloacetate can be limiting factors in the Krebb’s Cycle?

A

True (62)

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15
Q

Which enzyme converts pyruvate to OA?

A

Pyruvate carboxylase

63

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16
Q

Which reaction converts Pyruvate to Acetyl-CoA?

A

PDH reaction

63

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17
Q

True or False: The electron transport system is made up of a chain of election carrying proteins imbedded in the outer mitochondrail membrane?

A

False; Inner mito membrane

65

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18
Q

What is the first step in the ETS?

A

NADH dehydrogenase at Complex 1

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19
Q

Are cytochromes in the first or the second half of the ETS?

A

2nd half

66

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20
Q

Which molecule, NADH or FADH2 comes into the ETS at a higher energy level?

A

NADH

66

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21
Q

True or False: Coenzyme Q is the third complex (out of 4) in the ETS?

A

False; It is the second. 1) NADH dehydrogenase 2) Complex Q 3) Cytochromes 4) Cytochrome Oxidase (complex 4)
(66)

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22
Q

Does the ETS use oxidative phosphorylation or substrate level phosphorylation to produce ATP molecules?

A

Oxidative phosphorylation

67

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23
Q

How many ATP does one NADH molecule produce at the F1 particle? How many does FADH2 produce?

A

NADH produces 3
FADH produces 2
(67, 70)

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24
Q

True or False: The availability of O2 is typically a limiting factor for ETS regulation?

A

False

68

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25
Q

What are the 3 ways the ETS is regulated?

A

1) Supply of NADH, FADH2 (from KC)
2) Acceptor control (decreased ADP = decreased ETS)
3) O2 availability (ETS backs up w/out O2 = NADH accumulates = stops KC and PDH rxtn = lactate production
(68)

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26
Q

How many ATP are produced from 1 molecule of glucose?

A

38 in heart and liver
36 in skeletal muscle (NADH requires ATP to get into mito)
(69)

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27
Q

How many ATP are produced beginning with pyruvate?

A

(-2 NADH) therefore get 6 less ATP
32 heart/liver 30 skeletal muscle
(69)

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28
Q

How many ATP are produced beginning with acetyl CoA?

A

(-4 NADH) therefore get 12 less ATP
26 heart/liver 24 skeletal muscle
(69)

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29
Q

What enzyme works at the F1 particle?

A

ATP synthase

69

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30
Q

How is the ETS connected to ATP formation?

A

Chemiosmotic Coupling

70

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31
Q

Where are H+ pumped that create an electrochemical gradient in the ETS?

A

Inner Membrane Space

70

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32
Q

What do uncoupling agents do to the speed of the ETS and rate of ATP production?
What part of ETS do they avoid?

A

Increase ETS
Decrease ATP production
Bypass F1 particle (b/c aromatic organic acid = non polar)
(71)

33
Q

What does brown fat do to the H+ mechanism and is brown fat part of chemiosmotic coupling?

A

Wipes out H+ mechanism (leaky IMM) and
is a part of chemiosmotic coupling
(72)

34
Q

What % of all phosphorylation depends on oxidative phosphorylation?

A

90%

72

35
Q

What do ROS do?

A

Reactive Side Products create free radicals in other molecules
(73)

36
Q

What prevents and reverses the effects of ROS?

A

GSH (Glutathione)

73

37
Q

What do the enzymes glutathione peroxidase and glutathione reductase do? Which one contains selenium?

A

Eliminate hydrogen peroxide and lipid peroxides
Glutathione peroxidase contains selenium
(73)

38
Q

PDH reaction occurs b/t conversion of what two molecules?

A

Conversion of pyruvate to acetyl-CoA

74

39
Q

What is an oxidative alternative to the 1st part of glycolysis for catabolism of carbohydrates?

A

Pentose Shunt

75

40
Q

Where are the enzymes for the pentose shunt located?

A

Cytosol

75

41
Q

Where is the pentose shunt primarily important?

A

Liver, adipose, RBCs and Adrenal Cortex

75

42
Q

What is the first enzyme used in the pentose shunt?

A

G-6-P dehydrogenase

75

43
Q

What are the 3 things accomplished by the pentose shunt?

A

1) Generation of NADPH (for anabolic pathways: steroid and fatty acid synthesis, maintaining Fe in Hb)
2) Conversion of Hexoses to Pentoses
3) Complete oxidation of Pentoses

44
Q

What are the 3 ways of regulation of the pentose shunt?

A

1) NADPH inhibiting G-6-P dehydrogenase
2) Availability of NADP+
3) Utilization of Ribose-5-phosphate for nucleic acid synthesis (removal = accelerating the shunt)
(77)

45
Q

Where does gluconeogenesis take place?

A

Liver

79

46
Q

What is the anabolic pathway that reverses glycolysis?

A

Gluconeogenesis

79

47
Q

Which of the following are precursors for gluconeogenesis: Pyruvate, Lactate, Acetyl CoA, Fatty Acids, Amino Acids, Keytones?

A

Pyruvate, Lactate, Amino Acids

80

48
Q

What are the energy requirements for gluconeogenesis?

A 
6 ATP (technically 4 ATP + 2 GTP
(80)
49
Q

Which enzyme converts: Pyruvate to OA; F-1,6-bisPhosphate to F-6-P; G-6-P to Glucose?

A

Pyruvate to OA = Pyruvate Carboxylase
F-1,6-bisP to F-6-P = Fructose-1,6-bisPhosphatase
G-6-P to Glucose = Glucose-6-phosphatase
(80)

50
Q

True or False: UDP glucose is an active intermediate for glycogen synthase?

A

True

88

51
Q

What are the key regulation enzymes for glycogenesis and glycogenolysis?

A

Glycogenesis = glycogen synthase
Glycogenolysis = Phosphorylase (a-active, b-inactive)
(89)

52
Q

What is the first step in the cAMP mechanism?

A

Epinephrine activates adenylate cyclase which combines w/ ATP to form cAMP
(90)

53
Q

What does cAMP activate in the cAMP mechanism?

A

Phosphorylase Kinase
(a=active; breaks down Glycogen into G-1-P)
(90)

54
Q

Does skeletal muscle have to wait for epinephrine to activate the cAMP mechanism?

A

No, calcium also activates the cAMP cascade

90

55
Q

Since 1 cAMP can produce 25,000 G-1-P, how does this system shut down?

A

1) Phosphatases remove phosphate from phosphorylase A and phosphorylase kinase
2) Phosphodiesterase (breaks bond that makes cAMP cyclic, returning it to its AMP form)
(91)

56
Q

True or False: Caffeine acts as a non-competitive inhibitor on phosphodiesterase?

A

False; it is a COMPETITIVE inhibitor on phosphodiesterase = increase cAMP
(91)

57
Q

What is the defective enzyme in Von Gierke’s Disease and what are the effects?

A

Glucose-6-phosphatase
=increase glycogen, enlarged liver, hypoglycemia, ketosis
(93)

58
Q

Explain the Cori Cycle: where and when it happens?

A

Synthesis of glucose in the Liver from lactate produced in muscle during exercise
Has a net loss of 4 ATP
(94)

59
Q

What does fructose do to serum lipid levels? Why?

A

Elevates serum lipid levels (compared to glucose)
1) More fructose goes to liver (slower uptake by tissues)
2) Fructose bypasses PFK
(95)

60
Q

Are lipids polar or nonpolar?

A

Nonpolar

96

61
Q

What is more concentrated, triglyceride or glycogen?

A

Triglyceride b/c has 9 kcal/g (glucose = 4 ckal/g)

97

62
Q

How do stored triglycerides enter the blood?

A

Glycerol and unesterified fatty acids (ffa)

97

63
Q

What do FFA (free fatty acids) bind to in the blood?

A

Serum Albumin

97

64
Q

When considering lipolysis, when is ACTH, Glucagon, norepinephrin and epinephrine released?

A

ACTH - stress
Glucagon - routine decrease in blood glucose
Epi and NorEpi - sever decrease in blood glucose
(98)

65
Q

Which hormones mediate lipolysis?

A

Hormone Sensitive Lipase, cAMP, Protein Kinase

98

66
Q

Where is hormone sensitive lipase found and what does it do?

A

Found in adipocytes
Breaks down TGs
(98)

67
Q

What effect does insulin, thyroxine, and glucocorticoids have on lipolysis?

A

Insulin inhibits cAMP = inhibits lipolysis
Thyroxine (+) lipolysis
Glucocoricoids (+) lipolysis
(98)

68
Q

What effect does caffeine have on lipolysis?

A

Increases lipolysis (decreases phosphodiesterase activity, increase cAMP = (+) lipolysis)

69
Q

Absorbtion and oxidation of FAs requires Aerobic conditions everywhere except … ?

A

RBC’s
Brain
Nerves
(99)

70
Q

What is the respiratory quotient? What is the typical value if using fat? glucose?

A

Respiratory Quotient = CO2 produced/O2 used
Fat = 0.7
Glucose = 1.0
(99)

71
Q

After FAs are separated from Glycerol, what transfers FAs into blood?

A

Serum Albumin

98

72
Q

What transfers FAs into mitochondria?

A

Carnitine

100

73
Q

Where are ketone bodies primarily produced?

A

Produced in Liver from increased FA oxidation (arrival to liver) and decreased glucose utilization this increases Acetyl-CoA
(103)

74
Q

What is the common ketone intermediate?

A

HMG-CoA

103

75
Q

What is the signature enzyme for ketone production?

A

HMG-CoA Lyase (only found in liver mito)

103

76
Q

List the 3 ketone examples given in class

A

Acetone
Acetoacetate
3-hydroxybutyrate
(103)

77
Q

True or False: Ketones can be used as fuel by various tissues when glucose is in short supply?

A

True
Can be used by cardiac muscle, skeletal muscle, brain, etc.
(104)

78
Q

What is it called when you have increased ketone production, in urine, in blood, increased H+?

A 
Increase Ketone production = ketosis
in blood = ketonemia
in urine = ketonuria
Incr. H+ = ketoacidosis
(104)

Bio Chem 2 (4 decks)

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