Metabolism Overview Flashcards
(125 cards)
1
Q
4 characteristics of GLUT 2?
A
found in liver and pancreas
high Km
not responsive to insulin
cannot be saturated under normal conditions
2
Q
3 characteristics of GLUT 4?
A
found in adipose tissue and muscles
low Km
stimulated by insulin (mvt of GLUT 4 to the membrane by exocytosis)
3
Q
What is the normal glucose concentration in peripheral blood?
A
4-6 mM
4
Q
Where does glycolysis take place?
A
cytoplasm
5
Q
Does glycolysis require O2?
A
No
6
Q
What are the products of glycolysis?
A
Pyruvate + 2 ATP + 2 NADH
7
Q
Where is pyruvate converted to acetyl-CoA?
A
Mitochondria
8
Q
What are the products of pyruvate conversion to acetyl-CoA?
A
1 Acetyl-CoA + 1 CO2 + 1 NADH`
9
Q
Does pyruvate conversion require O2?
A
No
10
Q
In what organs does glycogenesis and glycogenolysis occur? For what purpose?
A
Liver: maintain constant levels of glucose
Muscles: provide glucose to the muscle during exercise
11
Q
Where do glycogenesis and glycogenolysis occur in the cell?
A
Cytoplasm
12
Q
Do glycogenesis and glycogenolysis require O2?
A
No
13
Q
Where does gluconeogenesis occur in the cell?
A
First step takes place in the mitochondria (pyruvate to oxaloacetate)
The rest of the reactions take place in the cytosol
14
Q
In what organs does gluconeogenesis occur? For what purpose?
A
Liver and kidneys
To maintain blood glucose levels during fasting
15
Q
Does gluconeogenesis require O2?
A
No
16
Q
What is the energy source for glycogenesis?
A
UTP
17
Q
What is the energy source for gluconeogenesis?
A
1 ATP + 1 GTP
18
Q
What happens to acetyl-CoA once it is synthesized from pyruvate? 2 options
A
- If ATP is needed: entry into TCA
2. If there is enough ATP: fatty acid synthesis
19
Q
What happens to pyruvate after glycolysis? 2 options
A
- If there isn’t enough acetyl-CoA: converted to acetyl-CoA
2. If there is enough acetyl-CoA: converted to oxoloacetate to enter gluconeogenesis
20
Q
What happens to the 2 NADH produced by glycolysis? 2 options
A
- If O2/mitochondria are present: oxidized by ETC
2. If O2/mitochondria aren’t present: oxidized by fermentation
21
Q
Where does the pentose phosphate pathway occur?
A
Cytoplasm
22
Q
What does the PPP generate?
A
NADPH and sugars
23
Q
What happens to NADPH after PPP? 3 options
A
- used for fatty acid synthesis
- bactericidal bleach in white blood cells
- acts as a reducing agent to maintain glutathione stores to protect against reactive O species
24
Q
What happens to the sugars after PPP?
A
Nucleotide synthesis
25
What metabolic processes does insulin stimulate?
1. PPP
2. Glycolysis
3. Fatty acid synthesis
4. Glycogenesis
26
What are the 3 pathways to generate acetyl-CoA?
1. Glycolysis and generation from pyruvate
2. Fatty acid oxidation = beta oxidation
3. From C skeletons of ketogenic amino acids, ketone bodies, and alcohol
27
Does the citric acid cycle require O2?
No, but it cannot occur without O2 being present, since it will be used by the ETC, which is the next step --> the citric acid cycle is an aerobic process!
28
Does the ETC require O2?
Yes
29
What are the products of the citric acid cycle?
3 NADH + 1 FADH2 + GTP + 2 CO2 + CoA-SH
30
What is another name for glycolysis?
Aerobic respiration
31
How much ATP does 1 NADH generate?
1.5 or 2.5 ATP
32
How much ATP does 1 FADH generate?
1.5 ATP
33
How much ATP does 1 GTP generate?
1 ATP
34
Is the electron transport of the ETC spontaneous or nonspontaneous?
Spontaneous = exergonic
35
What are the 2 transport mechanisms to bring NADH into the mitochondrial intermembrane space? How much ATP does each generate?
1. Glycerol-3-phosphate shuttle: 1.5 ATP/1 NADH
| 2. Malate aspartate shuttle: 2.5 ATP/1 NADH
36
How do I know which NADH shuttle a cell uses?
More aerobic organs will use the most efficient one: malate-aspartate shuttle
37
Where does oxidative phosphorylation occur?
Mitochondrial inner membrane, generating ATP into the matrix
38
How does low O2 affect oxidative phosphorylation?
Inhibits it
39
How does low O2 affect the concentration of NADH and FADH2?
Increases! They accumulate because they cannot enter the ETC
40
How does low O2 affect the citric acid cycle?
Inhibits it to stop producing NADH and FADH2, which are already abundant
41
How do high levels of ADP affect the citric acid cycle?
Stimulates it
42
How does citric acid cycle activation affect the concentration of NADH and FADH2?
Increases them
43
What metabolic processes does glucagon stimulate?
1. Gluconeogenesis
2. Fatty acid beta-oxidation
3. Ketolysis
4. Glycogenolysis
44
Where does fatty acid synthesis occur in the cell?
Cytoplasm
45
Where does fatty acid beta-oxidation occur?
Mitochondria (and a little in the peroxisome)
46
Where does conversion from pyruvate to acetyl-CoA occur?
Mitochondria
47
Where does ketogenesis occur?
Mitochondria
48
When does ketogenesis occur?
When acetyl-CoA accumulates in the fasting state
49
Where does ketolysis occur?
Mitochondria
50
What does ketolysis generate?
Acetyl-CoA
51
What does ketogenesis generate?
Ketone bodies for energy source
52
When does protein catabolism occur?
Extreme energy deprivation
53
In which organs does protein catabolism occur?
Muscle and liver
54
What is the purpose of fermentation?
Utilizing the excess NADH when there isn't oxygen or mitochondria and regenerates NAD+
55
When does excess fermentation occur?
When there isn't enough O2 for the NADH to go to the ETC
56
When does fatty acid synthesis occur?
When there is excess carbohydrates and protein from diet
57
In what organ does fatty acid synthesis occur?
Liver
58
In what compound are fatty acids stored? In which organ is this synthesized?
Tryacylglycerol
| Liver (and a little in adipose tissue)
59
Which metabolic processes do cortisol and cortisone stimulate?
1. Fatty acid beta-oxidation
| 2. Inhibition of glucose uptake
60
Which metabolic processes do catecholamines stimulate?
1. Glycogenolysis
| 2. Fatty acid beta-oxidation
61
What are ketone bodies made from?
Acetyl-CoA
62
Where does the citric acid cycle occur?
Mitochondria
63
What is the first step to start the citric acid cycle?
Citrate is formed from acetyl-CoA
64
What is oxidative stress?
Low NADPH level --> low glutathione --> reactive oxygen species from aerobic metabolism are not reduced --> oxidize lipid membranes (lysis) OR DNA damage (cancer)
65
What are flavoproteins?
A subclass of electron carriers derived from vitamin B2
66
When does the postprandial/well-fed state occur?
3-5 hours after a meal
67
What are the two types of cells that are insensitive to insulin?
Nervous tissue and red blood cells
68
When does the postabsorptive/fasting state occur?
12 hours after a meal
69
When does the prolonged fasting/starvation state occur?
24 hours after a meal
70
What is the impact of T3 and T4 on metabolic processes?
Increase the basal metabolic rate: increase O2 consumption
71
Which hormone is stronger: T3 or T4?
T3
72
What are the cells of the liver called?
Hepatocytes
73
What energy source does a resting muscle use?
Glucose and free fatty acids from the blood
74
What energy source does an active muscle use? 3 steps
First: creatine phosphate (ADP to ATP)
Second: Glycogen stores and fatty acids
Third: fatty acids
75
What energy source does the heart use?
Always fatty acid oxidation
76
What energy source does the brain and NS use?
Glucose and up to 2/3 ketone bodies during starvation
77
What is the respiratory quotient equal to?
RQ = CO2 produced / O2 consumed
78
Why are glucocorticoids related to stress-related weight gain?
They inhibit glucose uptake, so the excess glucose promotes fat storage
79
RQ of 0.7 indicates which fuel is being metabolized?
Lipids
80
RQ of 1 indicates which fuel is being metabolized?
Carbohydrates
81
RQ of 0.8-0.9 indicates which fuel is being metabolized?
Amino acids
82
Delta G of cAMP?
-50
83
Delta G of ATP?
-30
84
Delta G of creatine phosphate?
-40
85
Delta G of ADP?
-30
86
Delta G of AMP?
-10
87
Delta G of glucose-6-phosphate?
-14
88
How is mitochondrial acetyl-CoA carried to the cytoplasm?
Citrate shuttle
89
What are the reactants of cholesterol synthesis?
1 ATP + 1 NADPH + acetyl-CoA
90
Which anabolic process is referred to as nontemplate synthesis?
Fatty acid synthesis
91
How is cytoplasmic acetyl-CoA carries to the mitochondria?
Carnitine shuttle
92
Which amino acids are glucogenic?
All but leucine and lysine
93
Which amino acids are ketogenic?
```
FITTT + leucine and lysine:
Phe
Isole
threonine
trypto
tyrosine
```
94
How does the body get rid of excess nitrogen?
Urea cycle
95
What is the the only fatty acid that can be synthesized by humans de novo?
palmitic acid: 16:0 (16 Cs and 0 double bonds)
96
What are the electron donor and acceptor in Complex I of the ETC? Through?
```
NADH and CoQ
Flavin mononucleotide (FMN) and an iron-sulfer cluster
```
97
How many H+ are pumped in Complex III of the ETC?
4
98
What are the electron donor and acceptor in Complex II of the ETC? Through?
Succinate --> CoQ
| Through FADH2 and iron-sulfur cluster
99
How many H+ are pumped in Complex II of the ETC?
None
100
How many H+ are pumped in Complex I of the ETC?
4
101
How many H+ are pumped in Complex IV of the ETC?
2
102
What are the electron donor and acceptor in Complex IV of the ETC? Through?
Cytochrome c --> O2
| Through cytochrome ala3
103
What are the electron donor and acceptor in Complex III of the ETC?
CoQH2 --> cytochrome c
104
What are the two other carbohydrates that can be broken down to enter glycolysis?
Fructose and galactose
105
What are the 5 steps of fatty acid synthesis?
1. Activation
2. Bond formation
3. Reduction
4. Dehydration
5. Reduction
106
Structure of acetyl-CoA?
CH3-C=O-S-CoA
107
Structure of pyruvate?
CH3-C=O-COOH
108
What are the 4 steps of fatty acid beta-oxidation?
1. Oxidation
2. Hydration
3. Oxidation
4. Cleavage
109
How do I know how many cycles of beta-oxidation occur?
```
# cycles = n/2 - 1
n = # of Cs in chain
```
110
How many NADH and FADH2 are produced per cycle of beta oxidation?
1 each
111
What is the energy source for fatty acid beta oxidation?
1 ATP
112
How many ATP molecules are generated per acetyl-CoA?
10 ATP
113
Steps to find out the number of ATP molecules per fatty acid?
1. Calculate the number of cycles of beta-oxidation necessary
2. Calculate the number of NADH and FADH2 from those cycles (1 each per cycle) and how much ATP they generate
3. Divide number of Cs by 2 = number of acetyl-CoA molecules produced --> 10 ATP per molecule
4. Substract 1 ATP needed to activate the beta-oxidation
114
How many kcal/gram from proteins?
4
115
How many kcal/gram from carbs?
4
116
How many kcal/gram from fats?
9
117
What are the 3 roles of the peroxisome? What do they contain?
1. Breakdown of very long chain fatty acids through beta-oxidation
2. Phospholipid synthesis participation
3. Involved in pentose phosphate pathway
They contain hydrogen peroxide: H2O2
118
What are the 2 important unsaturated fatty acids that humans can synthesize?
alpha linolenic acid and linoleic acid
119
In what organs does fatty acid synthesis take place?
Liver
120
Where are fatty acids stored?
In adipose tissue
121
What are the 2 important ketone bodies?
1. Acetoacetate
| 2. 3-hydroxybutyrate
122
Which metabolic processes does growth hormone affect?
1. Stimulates fatty acid beta oxidation
| 2. Inhibits glycogenesis
123
What would cause the lowest ATP production: problem at complex I or IV?
IV
124
What are the reactants and products of fermentation in humans?
Glucose ---> 2 Pyruvate + 2 NADH + 2 ATP
| 2 Pyruvate + 2 NADH ---> 2 lactate
125
What can other types of fermentation produce?
In yeast: alcohol
