Biochemistry general Flashcards
1
Q
Pellagra 3Ds? +one additional symptom
A
Diarrhea, Dementia, Dermatitis (C3/C4); + hyperpigmentation of sun-exposed limbs.
2
Q
Diarrhea + Dementia + Dermatitis =?
A
Pellagra, when B3 (niacin) deficiency
3
Q
Katabolic reactions where NAD participates?
A
Glycolysis and beta-oxidation
4
Q
Anabolic reactions where NADP participates?
A
Cholesterol and fatty acid synthesis
5
Q
B3 is derived from ……
A
Tryptophan
6
Q
When/how often present symptoms in G6PD deficiency?
A
Episodically, when oxidative stress is increased
7
Q
NAD and NADP are important cofactors for ……… and ………. enzymes.
A
Reductase and dehydrogenase
8
Q
Apart from the catabolic reactions, NAD is needed for …………….. (2)
A
Cell signaling and DNR repair
9
Q
NAD is a key constituent in …………..
A
TCA cycle
10
Q
In TCA NAD is used ……. (3 reactions)
A
isocitrate dehydrogenase, alfa-ketoglutarate dehydrogenase, malate dehydrogenase
11
Q
Precursor for nucleotide synthesis in PPP?
A
Ribose-5-P
12
Q
In PPP are produced NADPH. Where is it used? (2)
A
Fatty acids and cholesterol synthesis
Glutathione antioxidant mechanism
13
Q
What vitamins are needed for vit. B3 synthesis? (2)
A
B2 and B6
14
Q
What 3 states can lead to pellagra apart usual deficiency of B3?
A
Hartnup disease
Malignant carcinoid syndrome (incr. tryptophan metabolism)
Isoniazid (decr. B6 - which is needed for B3 synthesis)
15
Q
The fate of pyruvate depends on …………..
A
the concentration of the oxygen in the tissue.
16
Q
In presence of oxygen, pyruvate …………
A
is converted to Acetyl-CoA and goes to TCA cycle.
17
Q
In the absence of oxygen, pyruvate ………
A
in converted to lactate in the cytosol.
18
Q
What reaction stops and induces pyruvate convertion to lactate in hypoxic conditions?
A
Pyruvate dehydrogenase is inhibited by NADH. This NADH is consumed in reaction pyruvate to lactate and converted to NAD.
19
Q
What enzymes are unidirectional and bypass gluconeogenesis? (3)
A
hexokinase, phosphofructokinase-1, and pyruvate kinase
20
Q
What is the principal step in gluconeogenesis?
A
pyruvate to oxaloacetate by pyruvate carboxylase + B7
21
Q
Fasting. When is gluconeogenesis and when glycogenolysis?
A
Glycogenolysis: first 12-18h
Gluconeogenesis: after 18-24h
22
Q
first reaction glycogenolysis in starvation?
A
breakage of 1-4 glycosidic linkage to form G-1-P
23
Q
the majority of ATP is produced in ……..
A
TCA in mitochondria
24
Q
What reaction is substrate-level phosphorylation?
A
Succinyl CoA –> Succinate via Succinyl-CoA synthase
25
What molecule is produced in the reaction of substrate-level phosphorylation?
GTP
26
Where is used a molecule that is produced in the reaction of substrate-level phosphorylation? (2)
Oxalate to PEP via phosphoenolpyruvate carboxykinase
or
ADP merge to GTP producing ATP
27
Neurological + lactatic acidosis + inc. serum alanine =?
Pyruvate dehydrogenase deficiency
28
What 2 amino acids are ketogenic?
Lysine and leucine
29
The diet for pyruvate dehydrogenase patients is consisted of: ..............
ketogenic diet: low carbo, high fat and medium proteins
30
When manifest symptoms of pyruvated dehydrogense deficiency?
infancy
31
B2 containing coenzymes constituent in ................
electron transport chain
32
What reaction in TCA produces FADH2?
Succinate to fumarate
33
Which reaction is inhibited in TCA if there is lack of B2?
Succinate to fumarate
34
Which reaction of TCA is in electron transport chain? Why?
succinate to fumarate. Because produce FADH, which is electron carrier.
35
Riboflavin --> FMN. How called reaction?
phosphorylation
36
FMN --> FAD. How called reaction?
phosphorylation
37
Where can be used FMN? (2)
integrated in a coenzymes-flavin complex
| convertion to FAD
38
FMN participate in ...... complex
Complex I
39
FAD participate in ...... complex
Complex II
40
Which complex participate in both TCA and electron transportation chain?
Complex II, FAD is cofactor.
41
Riboflavin deficiency symptoms?
cheilitis, angular stomatitis, eye defects: keratitis, neovascularization in cornea; seborrheic dermatitis, glossitis.
42
Reduced forms of FMN and FAD?
FMNH2 and FADH2
43
Muscle weakness + hypoketotic hypoglycemia + hypotonia =?
Primary carnitine deficiency
44
What process is impaired in carnitine deficiency?
Fatty acid transfer from cytoplasm to mitochondrial matrix
45
Why there is muscle weakness in carnitine deficiency?
No Acetyl-CoA from FA--> no production of ATP in TCA, therefore no energy.
46
Why there is decr. ketone bodies in carnitine deficiency?
No Acetyl-CoA from FA --> liver cannot produce ketone bodies during fasting periods
47
What catalyzes the first step of beta-oxidation?
Acyl-CoA dehydrogenase
48
What accumulates in case of medium chain acyl-coA dehydrogenase deficiency?
fatty acyl carnitines in the blood
49
vomiting+hypoketotic hypoglycemia+hepatomegaly/liver dysfunction + seizures/death=?
medium-chain acyl-coA dehydrogenase deficiency
50
When manifest hypoglycemia and low ketone bodies levels in medium-chain acyl-coA deficiency?
during significant fast
51
what is the treatment of MCAD?
avoid fasting, supply glucose during periods of illness
52
when start ketone bodies form in adults?
after 1-2 fasting
53
when children start to produce ketone bodies?
after 8-10 hours
54
why in adults ketone bodies synthesis starts later than in children when fasting?
Children have limited glucose reserves
55
what is the rate limiting enzyme in de novo fatty acid synthesis?
acetyl-coA carboxylase
56
What enzyme in inhibites in well-fed state in liver?
ATP inhibits isocitrate dehydrogenase in hepatocytes
57
In well-fed state there is high levels of .............. in mitochondria, which goes to .............
citrate goes to cytosol via citrate shuttle to form acetyl-coA
58
What causes upregulation of Acetyl-coA caboxylase?(2)
high levels of citrate; elevated insulin caused by high carbohydrate intake
59
What reaction catalyzes acetyl-coA carboxylase?
acetyl-coA --> malonyl-coA in the de novo fatty acid synthesis
60
why mitochondrial membranes are impermeable to FA?
due to their negative charge
61
how is prevented oxidation of newly synthesized de novo FA?
there is produced malonyl-coA, which inhibiths carnitine acyltrasferase
62
how is prevented transportation of newly synthesized de novo FA into mitochondria matrix?
same as prevention of beta oxidation - malonyl coa inhibits carnitine acyltransferase
63
Why there is a shift of reaction to ketone bodies production in case of starvation?
high levels of acetyl-coA and low levels of oxaloacetate, therefore TCA is inhibited. Then excessive AcylcoA is dericted to ketone bodies production
64
what 2 molecules are produced in beta-oxidation?
FADH2 and NADH
65
What molecule is needed for the synthesis of FA?
NADPH
66
essential fructosuria symptoms? (2)
fructose in blood and urine. In general asymptomatic condition.
67
What is alternative way to synthesize glucose in essential fructosuria?
Fructose --> fructose-6-P via hexokinase
68
when manifest vomiting and hypoglycemia in hereditary fructose intolerance?
20-30min after fructose ingestion.
69
why manifest hypoglycemia in hereditary fructose intolerance?
Hypoglycemia results from intracellular accumulation of fructose-1-phosphate and depletion of inorganic phosphate, which inhibit glycogenolysis and gluconeogenesis
70
hypoglycemia + vomiting + failure to thrive + jaundice + cirrhosis/hepatomegaly =?
hereditary fructose intolerance
71
3 main enzymes in fructose pathways?
fructokinase, aldolase B, triose kinase
72
what metabolic process is inhibited when alcohol consumed?
gluconeogenesis
73
alcohol does not inhibit glycogenolysis, but still eventually results in hypoglycemia, why?
at the beginning hepatic glycogenolysis is able to maintain euglycemia, however, after a prolonged time, glycogen is depleted, thus glucose in the blood also drops.
74
why alcohol inhibits gluconeogenesis?
because consumes NAD which is needed for gluconeogenesis pathways.
75
why lactate cannot be converted to pyruvate when alcohol is consumed?
lactate --> pyruvate requires NAD, which is reduced by alcohol dehydrogenase and aldehyde dehydrogenase. NADH/NAD ratio is increased, therefore pyruvate -->lactate use NADH
76
advanced renal insufficiency results in hypoglycemia. Why?
Impaired clearance of insulin is a major contributor to hypoglycemia in patients with advanced renal insufficiency
77
fructose is absorbed in intestines via ...... transporter
GLUT5
78
in fructokinase deficiency, ........ converts fructose into .... (compensation)
hexokinse; fructose-6-P
79
fructose-6-P got from alternative pathway in its deficiency can be matabolized in ..........
glycolytic pathway
80
why hereditary fructose intolerance is life threatening?
due to hypoglycemia
81
what is manifestatin of hypoglycemia?
vomiting, lethargy, sweating, dehydration
82
aldose reductase ........ (function)
converts glucose to sorbitol
83
why under normal conditions aldose reductase does not produce sorbitol?
because it has low affinity for glucose.
84
why breast milk can be used in fructose intolerance but not in galactosemia?
because it has maltose (2xglucose) and has lactose (glucose+galactose). No fructose - no problem. But it has galactose, therefore dangerous in galactosemia
85
The man source of NADPH is ......
PPP
86
where (body locations) is active PPP?
Cells, experiencing high oxidative stress (RBCs)
liver/adrenal cortex - they are involved in reductive biosynthesis of FA, cholesterol; also P450 metabolism
Phagocytic cell generating respiratory burst via NADPH oxidase
87
the PPP pathway consists of ..... and .....
oxidative and nonoxidative reactions. function independently depending on cellular requirements
88
body need nucleotides. how PPP works?
ribose-5-P is directed to nucleotide synthesis
89
in PPP there is excess of ribose-5-P. what happens then?
reaction is directed to glycolysis intermediates synthesis (glyceralaldehyde-3-P and fructose-6-P) then joins to glycolysis to produce ATP
90
oxidative PPP pathway cannot produce enough ribose-5-P. What happens?
nonoxidative pathway functions reverse; transketolase and transaldolase catalyze conversion of fructose-6-P and glyceraldehyde-3-P to ribose-5-P
91
nonspecific test to detect fructose?
copper reducing test
92
why copper reducing test can detect fructose?
because it is reducing sugar
93
in GALK deficiency there is buildup of .............
galactitol
94
in GALT deficiency there is build up of ..........
toxic metabolites such galactose-1-P, galactitol
95
Galactosemia + galactosuria + cataracts =?
galactokinase deficiency
96
vomiting + feeding intolerance + hepatomegaly + jaundice + cataracts + intelectual diasbility =?
classic galactosemia
97
When (age) manifest symptoms if there is deficiency in galactose pathway enzymes?
infants
98
what induces symptoms in galactosemia?
breastfeeding
99
in which metabolic disease may be e.coli sepsis?
classic galactosemia
100
fumarate ---> malate, enzyme?
fumarase
101
succinyl-CoA ---> succinate, enzyme?
succinyl thiokinase
102
succinate --> fumarate, enzyme?
succinate dehydrogenase
103
glyceraldehyde --> glyceraldehyde-3-P, enzyme?
triose kinase
104
what 2 metabolic mechanisms are impaired in hereditary fructose intolerance? why?
inhibited glycogenolysis and gluconeogenesis. Due to the consumption of phosphate
105
why urine dipstick is negative in hereditary fructose intolerance?
because it detects glucose, and here is defect in fructose pathway
