metabolism Flashcards
(91 cards)
1
Q
metab that occurs in mito
A
fatty acid BETA-ox.
acetyl co-A prod.
TCA cycle.
ox phos.
2
Q
metab that occurs in cytoplasm
A
glycolysis. FA synth. HMP shunt. protein synth (RER). steroid synth (SER).
3
Q
metab that occurs in both mito and cyto
A
Heme synth.
Urea cycle.
Gluconeogenesis.
HUGS take two.
4
Q
kinase
A
use ATP to add high-energy phosphate onto substrate
5
Q
phosphorylase
A
adds inorganic phosphate onto substrate without using ATP
6
Q
phosphatase
A
removes phosphate group from substrate
7
Q
dehydrogenase
A
oxidizes substrate
8
Q
carboxylase
A
transfers CO2 groups with help of BIOTIN
9
Q
rate-determining enzyme: glycolysis
A
phosphofructokinase-1
10
Q
rate-determining enzyme: gluconeogenesis
A
fructose-1,6-bisphosphatase
11
Q
rate-determining enzyme: TCA cycle
A
isocitrate dehydrogenase
12
Q
rate-determining enzyme: glycogen synthesis
A
glycogen synthase
13
Q
rate-determining enzyme: glycogenolysis
A
glycogen phosphorylase
14
Q
rate-determining enzyme: HMP shunt
A
glucose-6-phosphate dehydrogenase
15
Q
rate-determining enzyme: de novo pyrimidine synth
A
carbamoyl phosphate synthetase II
16
Q
rate-determining enzyme: de novo purine synth
A
glutamine-PRPP amidotransferase
17
Q
rate-determining enzyme: urea cycle
A
carbamoyl phosphate synthetase I
18
Q
rate-determining enzyme: fatty acid synth
A
acetyl-coA carboxylase (ACC)
19
Q
rate-determining enzyme: fatty acid oxidation
A
carnitine acyltransferase 1
20
Q
rate-determining enzyme: ketogenesis
A
HMG-CoA synthase
21
Q
rate-determining enzyme: chol synth
A
HMG-CoA reductase
22
Q
aerobic metab of glucose produces?
A
32 ATP: malate-aspartate shuttle in heart, liver.
30 ATP: glycerol-3-phosphate shuttle in muscle.
23
Q
anaerobic glycolysis produces?
A
2 net ATP per glucose molec
24
Q
activated carrier of phosphoryl
A
ATP
25
activated carrier of electrons
NADH.
NADPH.
FADH2.
26
activated carrier of acyl
coenzyme A.
| lipoamide.
27
activated carrier of CO2
biotin
28
activated carrier of 1 carbon units
tetrahydrofolate
29
activated carrier of CH3 groups
SAM
30
activated carrier of aldehydes
TPP (thiamine pyrophosphate, B1)
31
universal electron acceptor: NAD+
nicotinamide.
from vit B3.
used in catabolic processes to carry reducing equivalents away as NADH.
32
universal electron acceptor: NADP+
nicotinamide.
NADPH made in HMP SHUNT.
used in anabolic processes as a SUPPLY of reducing equivalents.
33
universal electron acceptor: FAD+
flavin nucleotides.
| from vit B2.
34
processes that use NADPH
1. anabolic processes: steroid and FA synth.
2. respiratory burst.
3. P450.
4. glutathione reductase.
35
hexokinase/glucokinase
phosphorylate glucose to yield GLUCOSE-6-PHOSPHATE.
1st step of glycolysis AND glycogen synth in liver, depending on enz location.
36
hexokinase
UBIQUITOUS.
high affinity (low Km).
low capacity (low Vmax).
NOT induced by insulin.
37
what inhibits hexokinase?
glucose 6-phosphate via feedback inhib
38
glucokinase
LIVER and BETA CELLS of pancreas.
low affinity (high Km).
high capacity (high Vmax).
induced by insulin.
39
what does glucokinase with excess glucose?
phosphorylates it (after a meal) to SEQUESTER it in the liver - liver serves as blood glucose buffer
40
which steps in glycolysis require ATP?
1. hexo/glucokinase.
| 2. phosphofructokinase-1.
41
what inhibits glucokinase?
fructose-6-phosphate
42
what inhibits PFK1?
ATP.
| citrate.
43
what stimulates PFK1?
AMP.
| fructose 2,6-bisphosphate.
44
which steps in glycolysis produce ATP?
1. phosphoglycerate kinase.
| 2. pyruvate kinase.
45
what inhibits PK?
ATP.
| alanine.
46
what stimulates PK?
fructose 1,6-bisphosphate
47
fructose bisphosphatase 2
active in FASTING state:
increase glucagon = cAMP = protein kinase A = increase fructose bisphosphatase 2.
F26BP to F6P for gluconeogenesis.
decrease PFK2 = less glycolysis.
48
phosphofructokinase-2
active in FED state:
increase insulin = decrease cAMP = decrease protein kinase A = increase PFK2.
F26BP stimulates PFK1 for more glycolysis.
decrease fructose bisphosphatase 2.
49
pyruvate dehydrogenase complex RXN
pyruvate + NAD+ + CoA =
| acetyl coA + CO2 + NADH
50
pyruvate dehydrogenase complex COFACTORS
1. TPP (B1)
2. FAD (B2)
3. NAD (B3)
4. CoA (B5)
5. lipoic acid
51
what activates pyruvate dehydrogenase complex?
exercise:
increased NAD+/NADH ratio.
increased ADP.
increased Calcium.
52
what other complex is similar to pyruvate dehydrogenase complex?
alpha-ketoglutarate dehydrogenase complex in TCA cycle. same cofactors, similar substrate.
alpha-KG --> succinyl CoA.
53
what inhibits lipoic acid?
arsenic - cause vomiting, pain, rice water stools, garlic breath, delirium.
54
TX of arsenic poisoning
dimercaprol (chelator) to displace arsenic ions
55
pyruvate dehydrogenase deficiency
back up of substrate (pyruvate, alanine).
increased LDH activity to regenerate NAD+ causes LACTIC ACIDOSIS.
can be congenital or
acquired (alcoholics, B1 def).
56
findings in pyruvate dehydrogenase deficiency
neuro defects
57
TX of pyruvate dehydrogenase deficiency
increased intake of KETOGENIC nutrients-
high fat content or
increased Lysine and Leucine (the only purely ketogenic AAs)
58
pyruvate can be metabolized into:
1. alanine.
2. oxaloacetate.
3. acetyl CoA.
4. lactate.
59
function of alanine from pyruvate
carries amino groups from muscle TO LIVER
60
function of oxaloacetate from pyruvate
replenish TCA cycle or
| used in gluconeogenesis
61
function of acetyl CoA from pyruvate
transition from glycolysis to TCA
62
function of lactate from pyruvate
end of anaerobic glycolysis
63
which organs use anaerobic glycolysis (and thus produce lactate)?
```
RBCs.
leukocytes.
kidney medula.
testes.
lenses.
cornea.
```
64
what inhibits pyruvate dehydrogenase?
ATP.
acetyl CoA.
NADH.
65
irreversible enzymes in TCA
1. pyruvate dehydrogenase.
2. citrate synthase.
3. isocitrate dehydrogenase.
4. alpha-ketoglutarate dehydrogenase.
66
intermediates in TCA (in order)
```
Citrate.
Isocitrate.
alpha-Ketoglutarate.
Succinyl CoA.
Succinate.
Fumarate.
Malate.
Oxaloacetate.
```
"Citrate Is Kreb's Starting Substrate For Making Oxaloacetate"
67
NADH electrons enter mito...
via malate-aspartate
| or glycerol-3-phosphate shuttle.
68
where does FADH2 enter ETC/oxphos?
complex II (at lower energy level than NADH)
69
ATP produced by ATP synthase
using proton gradient formed in intermembranous space.
1 NADH = 3 ATP.
1 FADH2 = 2 ATP.
70
ox phos poison: electron transport inhibitors
directly inhibit ETC, causing decreased proton gradient and block of ATP synth.
1. rotenone.
2. CN-
3. antimycin A.
4. CO
71
ox phos poison: ATP synthase inhibitors
directly inhibit mito ATP synthase, causing increased proton gradient.
NO ATP IS PRODUCED bc electron transport stops.
drug: oligomycin
72
ox phos poison: uncoupling agents
increase permeability of membrane, causing decreased proton gradient and increased O2 consumption.
ATP synth stops but ETC continues.
produces heat.
1. 2,4-dinitrophenol.
2. aspirin (overdose).
3. thermogenin (brown fat).
73
gluconeogenesis occurs in?
LIVER.
| enzymes also found in kidney, intestinal epith.
74
gluconeogenesis irreversible enzymes
Pyruvate carboxylase.
PEP carboxykinase.
Fructose-1,6-bisphosphatase.
Glucose-6-phosphatase.
"Pathway Produces Fresh Glucose"
75
deficiency of gluconeogenesis enzymes leads to?
hypoglycemia
76
why cant MUSCLE participate in gluconeogenesis?
it lacks glucose-6-phosphatase
77
what type of FA can also contribute to gluconeogenesis?
odd-chain FA: yield 1 propionyl CoA during metabolism, which can enter TCA as succinyl CoA and undergo gluconeogenesis.
*even-chain FAs only yield acetyl CoA equivalents
78
pyruvate carboxylase
in mito.
pyruvate to oxaloacetate.
requires biotin, ATP.
activated by acetyl CoA.
79
PEP carboxykinase
in cytosol.
oxaloacetate to PEP.
requires GTP.
80
fructose-1,6-bisphosphatase
in cytosol.
| fructose-1,6-bisphosphate to fructose-6-phosphate.
81
glucose-6-phosphatase
in ER.
| glucose-6-phosphate to glucose.
82
HMP shunt
key role: provide NADPH from abundant G6P supply.
aka pentose phosphate pathway.
83
phases of HMP shunt
1. oxidative (irreversible).
| 2. nonoxidative (reversible).
84
products of HMP shunt
1. NADPH.
2. ribose.
3. glycolytic intermediates (G3P, F6P).
85
sites of HMP shunt
CYTOPLASM-
lactating mammary glands.
liver, adrenal cortex (FA/steroid synth).
RBCs (glutathione reduction).
86
ATP in HMP shunt
none used or produced
87
oxidative rxn of HMP shunt
glucose 6-phosphate
yields 2 NADPH, CO2, ribulose-5P
(multiple in-between steps)
via G6P dehydrogenase.
*RATE-LIMITING STEP
88
nonoxidative rxn of HMP shunt
ribulose-5P (from oxidative phase)
yields ribose-5P, G3P, F6P
(multiple in-between steps)
via transketolase with B1 cofactor.
89
what enz is activated in respiratory (oxidative) burst?
NADPH oxidase -
membrane bound.
in neutrophils, monocytes.
*NADPH involved in ROI production and neutralization
90
role of resp burst
immune response: rapid release of reactive oxygen intermediates (ROIs)
91
sequence of enzymes in ROI prod
NADPH oxidase.
superoxide dismutase.
myeloperoxidase OR catalase/glutathione peroxidase
