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Bio Chem 2 > 2nd Midterm > Flashcards

2nd Midterm Flashcards

(78 cards)

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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

65

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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
What are the 3 ways the ETS is regulated?
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)
26
How many ATP are produced from 1 molecule of glucose?
38 in heart and liver 36 in skeletal muscle (NADH requires ATP to get into mito) (69)
27
How many ATP are produced beginning with pyruvate?
(-2 NADH) therefore get 6 less ATP 32 heart/liver 30 skeletal muscle (69)
28
How many ATP are produced beginning with acetyl CoA?
(-4 NADH) therefore get 12 less ATP 26 heart/liver 24 skeletal muscle (69)
29
What enzyme works at the F1 particle?
ATP synthase | 69
30
How is the ETS connected to ATP formation?
Chemiosmotic Coupling | 70
31
Where are H+ pumped that create an electrochemical gradient in the ETS?
Inner Membrane Space | 70
32
What do uncoupling agents do to the speed of the ETS and rate of ATP production? What part of ETS do they avoid?
Increase ETS Decrease ATP production Bypass F1 particle (b/c aromatic organic acid = non polar) (71)
33
What does brown fat do to the H+ mechanism and is brown fat part of chemiosmotic coupling?
Wipes out H+ mechanism (leaky IMM) and is a part of chemiosmotic coupling (72)
34
What % of all phosphorylation depends on oxidative phosphorylation?
90% | 72
35
What do ROS do?
Reactive Side Products create free radicals in other molecules (73)
36
What prevents and reverses the effects of ROS?
GSH (Glutathione) | 73
37
What do the enzymes glutathione peroxidase and glutathione reductase do? Which one contains selenium?
Eliminate hydrogen peroxide and lipid peroxides Glutathione peroxidase contains selenium (73)
38
PDH reaction occurs b/t conversion of what two molecules?
Conversion of pyruvate to acetyl-CoA | 74
39
What is an oxidative alternative to the 1st part of glycolysis for catabolism of carbohydrates?
Pentose Shunt | 75
40
Where are the enzymes for the pentose shunt located?
Cytosol | 75
41
Where is the pentose shunt primarily important?
Liver, adipose, RBCs and Adrenal Cortex | 75
42
What is the first enzyme used in the pentose shunt?
G-6-P dehydrogenase | 75
43
What are the 3 things accomplished by the pentose shunt?
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
What are the 3 ways of regulation of the pentose shunt?
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
Where does gluconeogenesis take place?
Liver | 79
46
What is the anabolic pathway that reverses glycolysis?
Gluconeogenesis | 79
47
Which of the following are precursors for gluconeogenesis: Pyruvate, Lactate, Acetyl CoA, Fatty Acids, Amino Acids, Keytones?
Pyruvate, Lactate, Amino Acids | 80
48
What are the energy requirements for gluconeogenesis?
``` 6 ATP (technically 4 ATP + 2 GTP (80) ```
49
Which enzyme converts: Pyruvate to OA; F-1,6-bisPhosphate to F-6-P; G-6-P to Glucose?
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
True or False: UDP glucose is an active intermediate for glycogen synthase?
True | 88
51
What are the key regulation enzymes for glycogenesis and glycogenolysis?
Glycogenesis = glycogen synthase Glycogenolysis = Phosphorylase (a-active, b-inactive) (89)
52
What is the first step in the cAMP mechanism?
Epinephrine activates adenylate cyclase which combines w/ ATP to form cAMP (90)
53
What does cAMP activate in the cAMP mechanism?
Phosphorylase Kinase (a=active; breaks down Glycogen into G-1-P) (90)
54
Does skeletal muscle have to wait for epinephrine to activate the cAMP mechanism?
No, calcium also activates the cAMP cascade | 90
55
Since 1 cAMP can produce 25,000 G-1-P, how does this system shut down?
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
True or False: Caffeine acts as a non-competitive inhibitor on phosphodiesterase?
False; it is a COMPETITIVE inhibitor on phosphodiesterase = increase cAMP (91)
57
What is the defective enzyme in Von Gierke's Disease and what are the effects?
Glucose-6-phosphatase =increase glycogen, enlarged liver, hypoglycemia, ketosis (93)
58
Explain the Cori Cycle: where and when it happens?
Synthesis of glucose in the Liver from lactate produced in muscle during exercise Has a net loss of 4 ATP (94)
59
What does fructose do to serum lipid levels? Why?
Elevates serum lipid levels (compared to glucose) 1) More fructose goes to liver (slower uptake by tissues) 2) Fructose bypasses PFK (95)
60
Are lipids polar or nonpolar?
Nonpolar | 96
61
What is more concentrated, triglyceride or glycogen?
Triglyceride b/c has 9 kcal/g (glucose = 4 ckal/g) | 97
62
How do stored triglycerides enter the blood?
Glycerol and unesterified fatty acids (ffa) | 97
63
What do FFA (free fatty acids) bind to in the blood?
Serum Albumin | 97
64
When considering lipolysis, when is ACTH, Glucagon, norepinephrin and epinephrine released?
ACTH - stress Glucagon - routine decrease in blood glucose Epi and NorEpi - sever decrease in blood glucose (98)
65
Which hormones mediate lipolysis?
Hormone Sensitive Lipase, cAMP, Protein Kinase | 98
66
Where is hormone sensitive lipase found and what does it do?
Found in adipocytes Breaks down TGs (98)
67
What effect does insulin, thyroxine, and glucocorticoids have on lipolysis?
Insulin inhibits cAMP = inhibits lipolysis Thyroxine (+) lipolysis Glucocoricoids (+) lipolysis (98)
68
What effect does caffeine have on lipolysis?
Increases lipolysis (decreases phosphodiesterase activity, increase cAMP = (+) lipolysis)
69
Absorbtion and oxidation of FAs requires Aerobic conditions everywhere except ... ?
RBC's Brain Nerves (99)
70
What is the respiratory quotient? What is the typical value if using fat? glucose?
Respiratory Quotient = CO2 produced/O2 used Fat = 0.7 Glucose = 1.0 (99)
71
After FAs are separated from Glycerol, what transfers FAs into blood?
Serum Albumin | 98
72
What transfers FAs into mitochondria?
Carnitine | 100
73
Where are ketone bodies primarily produced?
Produced in Liver from increased FA oxidation (arrival to liver) and decreased glucose utilization *this increases Acetyl-CoA* (103)
74
What is the common ketone intermediate?
HMG-CoA | 103
75
What is the signature enzyme for ketone production?
HMG-CoA Lyase (only found in liver mito) | 103
76
List the 3 ketone examples given in class
Acetone Acetoacetate 3-hydroxybutyrate (103)
77
True or False: Ketones can be used as fuel by various tissues when glucose is in short supply?
True Can be used by cardiac muscle, skeletal muscle, brain, etc. (104)
78
What is it called when you have increased ketone production, in urine, in blood, increased H+?
``` Increase Ketone production = ketosis in blood = ketonemia in urine = ketonuria Incr. H+ = ketoacidosis (104) ```

Bio Chem 2 (4 decks)

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