Biochem Flashcards
(271 cards)
1
Q
Enzymes of glycolytic enzyme deficiency
A
Aldolase A, enolase, phosphofructokinase, pyruvate kinase
2
Q
What do red cells require for energy production?
A
Anaerobic glycolysis
3
Q
In which metabolic process is pyruvate carboxylase seen?
A
One of the gluconeogenetic pathway enzymes in mitochondria
Catalyzes the conversion of pyruvate to oxaloacetatew
4
Q
Clinical manifestation of pyruvate carboxylase deficiency
A
Lactic acidosis and fasting hypoglycemia
5
Q
What is primase?
A
RNA polymerase
6
Q
Where is the starting point of DNA polymerase in the RNA primer as a starting point for synthesis?
A
In the 3’ hydroxyl group of the RNA primer
7
Q
Crucial enzyme for bacterial replication as DNA polymerase
A
Primase
8
Q
Primary enzyme responsible for synthesis of daughter DNA strands
A
DNA polymerase III
9
Q
Functions chiefly to replace the RNA primers with DNA segments
A
DNA polymerase I
10
Q
Where does heme synthesis is done?
A
Partly in the mitochondria and partly in the cytoplasm
11
Q
When the erythrocyte mature and looses the mitochondria, which ability is lost?
A
The ability to generate heme and there hemoglobin
12
Q
Which heme synthesis substrates are seen in mitochondria of erythrocyte precursors?
A
Protoporphyrinogen IX
Protoporphyrin IX
Heme
13
Q
What type of disorder is orotic aciduria?
A
Pyrimidine metabolism
14
Q
What characterizes orotic aciduria?
A
Hypochromic megaloblastic anemia, neurologic abnormalities, growth retardation and excretion of high amounts of orotic acid in the urine
15
Q
First substrates for pyrimidine synthesis
A
ATP, CO2 and gluthamine
16
Q
Which enzyme is required to form carbamoyl phosphate in pyrimidine synthesis?
A
Carbamoyl phosphate synthase II
17
Q
Regulatory step for pyrimidine synthesis
A
Carbamoyl phosphate
18
Q
Which are the defective enzymes in orotic aciduria?
A
Orotate phosphoribosyl transferase and OMP decarboxylase
19
Q
What is the final product of pyrimidine synthesis?
A
Orotate to uridine 5’ monophosohate (UMP)
20
Q
What needs to be supplemented in Orotic aciduria?
A
Uridine
21
Q
When is indicated pyridoxine supplementation?
A
During treatment with isoniazid
22
Q
Required for hydroxylation of proline and lysine residues in collagen synthesis
A
Ascorbic acid (vitamin C)
23
Q
How does uridine supplementation improves symptoms of orotic aciduria?
A
By inhibiting carbamoyl phosphate synthase II
24
Q
What is the product of phenylalanine hydroxylase?
A
Tyrosine
25
What is deficient in homozygous phenylketonuria patients?
Phenylalanine hydroxylase
26
Which enzyme is inhibited by the excess of phenylalanine? What is its function?
Tyrosinase, enzyme responsible for the synthesis of melanin from tyrosine
27
When do PKU patients develop mental retardation and the other clinical findings?
By 6th months
28
What is the treatment for Hartnup disease?
Nicotinic acid or nicotinamide and a high protein diet
29
Which vitamin may be deficient in case of Hartnup disease?
Niacin
30
What causes niacin deficiency in Hartnup disease?
Loss of dietary tryptophan
31
What could cause loss of tryptophan in Hartnup disease?
Defective intestinal and renal tubular absorption
32
After how much time of starvation does the body start using lipids instead of glucose?
After 16-24 hours
33
Which enzyme deficiency leads to impaired beta oxidation?
Acyl CoA dehydrogenase
34
Who causes Von Gierke disease?
Deficiency of glucose 6 phosphatase
35
Clinical manifestations of glucose 6 phosphatase enzyme
Hypoglycemia, stunted growth, lactic acidosis and hypertriglyceridemia
36
Enzyme that catalyzes the first step in fatty acid synthesis
Acetyl CoA carboxylase
37
What is the result of splice site mutations?
Result in the production of larger proteins with altered function but preserved immune reactivity
38
Why is lipoic acid for pyruvate dehydrogenase?
Because it is involved in the decarboxylation of alpha ketoacids and the transfer of alkyl groups
The transfer of alkyl group from pyruvate to coenzyme A is essential for the function of pyruvate dehydrogenase
39
Which enzymes do PDH require?
CoA, FAD, lipoic acid, NAD and thiamine pyrophosphate
40
What is the result of decreased functioning of pyruvate dehydrogenase?
Increased conversion of pyruvate to lactate
41
Why does pyruvate becomes lactate in absence of the coenzymes?
By the enzyme lactate dehydrogenase in an effort to regenerate NAD+, and this will eventually lead to lactic acidosis
42
In which pathways does lipoic acid works?
TCA cycle
Alpha ketoglutarate dehydrogenase
Branched chain ketoacid dehydrogenase
43
Which type of disorder is citrullinemia?
Urea cycle that results from deficiency of argininosuccinate synthase
44
Cofactor needed for argininosuccinate synthase
ATP
45
Which deficiency is seen in methyl alonic aciduria?
Vitamin B12 dependent enzyme methylmalonate mutase
46
Results from a deficiency in cystathione synthase
Homocystinuria
47
What characterizes homocystinuria?
Premature atherosclerosis
48
how is homocysteine by the body?
Conversion to cysteine by combined actions of two vitamin B6 requiring enzymes
Conversion to methionine by folate and vitamin B 12 dependent process
49
Which enzymes in homocysteine require vitamin B6?
Cystathionine synthase and cystathionase
50
Pathology associated to pyrimidine synthesis
Orotic aciduria
51
Which enzyme is deficient in orotic aciduria?
Orotate phosphoribosyl transferase
52
Which coenzyme does Orotate phosphoribosyl transferase require?
Glutathione
53
Glycogen storage disease type V
McArdle disease
54
Which enzyme is deficient in McArdle disease?
Myophosphorylase
55
Deficiency of this enzyme leads to decreased breakdown of glycogen during exercise, resulting in poor exercise tolerance, muscle cramps and rhabdomyolysis
Myophosphorylase
56
This pathway maintains cellular NADPH levels and produces oentose sugars for nucleotide synthesis
Pentose phosphate pathway (hexose monophosphate pathway)
57
What happens in Pentose phosphate pathway (hexose monophosphate pathway) ?
Conversion of glucose 6 phosphate to 6 phosphogluconate by glucose 6 phosphate
58
This rRNA molecule is essential for initiation of protein synthesis in prokaryotes
16S rRNA
59
Where is 16S rRNA found?
In the prokaryotic 30S ribosomal subunit
60
What is the function of 16S rRNA subunit?
Expresses a sequence complementary to Shine Dalgarno sequence in all prokaryotic mRNA
61
These two complementary sequences allow the mRNA and the 30S ribosomal subunit to bind in preparatio. For protein trnalation
16S rRNA and Shine Dalgarno
62
How is the protein synthesis made, after binding of 30S ribosomal subunit is bound to mRNA?
An initiator tRNA binds to the AUG codon, the 50S ribosomal subunit joins the complex and protein synthesis begins
63
Where is 23S rRNA is found?
In the 50S ribosomal subunit
64
What is 23S rRNA? And what is its function?
Its a peptidyltransferase, who facilitates peotide bond formation in protein translation
65
Process by which the ribosome advances to the next mRNA codon
Translocation
66
It recognizes and binds the mRNA codon and assures placement of the proper amino acid in the growing polypeptide chain
Anticodon
67
Of the tRNA which is the site of amino acid attachment?
3'
68
What composes 5' end of tRNA?
Of terminal guanosine
69
Responsible for transporting amino acids to the site of protein synthesis and introducing them into the growing polypeptide chain at the correct locations
tRNA
70
What is the function of the anticodon?
Recognizes a specific codon on the mRNA molecule
71
Who brakes down glycogen?
Glycogen phosphorylase
72
Who phosphorylates (activates) glycogen phosphorylase?
Phosphorylase kinase
73
Who dephosphorylates (inactivates) glycogen phosphorylase?
Phosphoprotein phosphatase
74
Main organs where glycogen works
Liver and muscle
75
In the liver how is Phosphorylase kinase activated?
Through the binding of epinephrine and glucagon to Gs protein coupled receptors, which increases cAMP concentrations
76
In the muscle how is Phosphorylase kinase activated?
Increased intracellular calcium and epinephrine
77
Factors that inhibit phosphorylated glycogen phosphorylase
By ATP and glucose 6 phosphate in both liver and muscle cells
78
Process where astrocytes and neurons interact to regulate the metabolism of glutamate, glutamine and ammonia
Glutamate glutamine cycle
79
Which is the metabolic process of glutamine in the brain?
Glutamine is released by astrocytes and taken up by neuron, where it is either converted to glutamate for use as a neurotransmitter or transaminated into alpha ketoglutarate for use in krebs cycle
80
Which enzyme detoxifies ammonia to glutamine?
Glutamate dehydrogenase
81
What is the final effect of Glutamate dehydrogenase on the brain?
Detoxifies ammonia to glutamine, depleting alpha ketoglutarate and further impairing energy metabolism in the brain
82
Responsible for transport of fatty acids into the mitochondria for beta oxidation
Carnitine
83
When does impaired beta oxidation of fatty acids to acetyl CoA occur?
With excessive alcohol consumption
84
Who metabolizes lactate?
Liver
85
Tryptophan derivative formed by bacteria in the gut and normally cleared by the liver
Oxindole
86
When do we see elevated levels of oxindole?
In patients with hepatic encephalopathy
87
What is the result of hyperammonemia in hepatic encephalopathy?
Depletion of alpha ketoglutarate, causing inhibition of Krebs cylce
Depletes glutamate and causes accumulation of glutamine, resulting in astrocyte swelling and dysfunction
88
Glutamate excitatory or inhibitory neurotransmitter?
Excitatory
89
Allosteric activator of pyruvate carboxylase
Acetyl CoA
90
Who allosterically inhibits pyruvate kinase?
Alanine
91
When are methylmalonilic acid levels increased?
With vitamin B12 deficiency
92
Hallmark of erythropoietin protoporphyria
Increased erythrocyte protoporphyrin
93
Essential in de novo pathway for dTMP production because regulates the supply of four nucleotide precursors of DNA replication
Thymidylate synthase
94
Percentage pf thymidine kinase that normally accounts for dTMP synthesis
5-10%
95
What is elevated in folate deficiency?
Homocysteine
96
Major source of nitrogen in the synthesis of nucleotides
Glutamine
97
Contributes a nitrogen atom to the biosynthesis of dUMP
Glutamine
98
In case of folate synthesis, what is not formed?
Deoxythymidine monophosphate (dTMP)
99
What is the result of folate deficiency inhibiting the formation of Deoxythymidine monophosphate (dTMP)?
Limits DNA synthesis and promotes megaloblastosis and erythroid precursor cell apoptosis
100
Which antibodies confirm the diagnosis of rheumatoid arthritis?
Anti cyclic citrullinated peptide (anti CCP)
101
What is the citrullation?
Tissue inflammation causes arginine residues in proteins such as vimentin to be enzymatically converted into citrulline
102
What does antiphospholipid antibody causes?
Hypercoagulability, paradoxical partial thromboplastin time (PTT) prolongation, and recurrent miscarriages
103
What could be the result of homozygous mutation of glucokinase in pregnant women?
Fetal growth retardation and hyperglycemia at birth
104
What is the importance of PI3K/Akt/mTOR pathway?
Is an intracellular signaling pathway important for anti apoptosis, cellular proliferation and angiogenesis
105
Which factors enhance the activity of PI3K/Akt/mTOR pathway contributing with cancer pathogenesis?
Growth factor receptors, Akt, mTOR, or PTEN
106
A disease caused by tissue deposition of monosodium urate crystals
Gout
107
Which is a known risk factor for gout?
Elevated uric acid levels
108
Which is a possible cause of hyperuricemia?
Increased purine metabolism
109
Its the enzyme responsible for the production of the activated ribose necessary for de novo synthesis of purity and pyrimidines Nucleotides
Phosphoribosyl pyrophosphate (PRPP)
110
What could be the result of more purine molecules undergoing degradation?
Hyperuricemia and an increased risk of gout
111
Disease caused by glucose 6 phosphate deficiency
Von Gierke disease
112
Disease caused by acid maltase deficiency
Pompe disease
113
In which patients does gout occur more frequently?
In patients with activating mutation involving phosphoribosyl pyrophosphate synthase due to increased production and degradation of purines
114
What is mainly affected in acute gouty arthritis?
First metatarsophalangeal joint or knee
Swelling, erythema and exquisite tenderness
Symptoms develop rapidly over 24 hours
115
How is the diagnosis made in Acute gouty arthritis?
Joint aspiration shows needle shapped, negatively birefringent crystals
116
Treatment for acute gouty arthritis
NSAIDs (eg naproxen, indomethacin) preferred if no contraindications
Colchicine used as a second line therapy
117
Which are the primary cells responsible for intense inflammatory response seen in patients with gout?
Neutrophils
118
Which is the function of Colchicine?
Impairs neutrophil migration and phagocytosis by interfering with microtubule formation
119
Another function of this drug is to decrease tyrosine phosphorylation in in response to monosodium urate crystals
Colchicine
120
Which drug inhibits mast sell degranulation?
Cromolyn sodium
121
Which cell functions require Ubiquitination?
```
Antigen processing
Muscle wasting
Cell cycle regulation
DNA repair
Disposal of misfolded proteins and regulatory enzymes
```
122
Which system impairment can contribute to the development of neurodegenerative disorders such as Parkinson disease and Alzheimer?
Ubiquitin-proteasome system
123
Which genes promote the degradation of misfolded proteins via the ubiquitin proteasome system?
Parkin
PINK1
DJ-1
124
Which genes are mutated in cases of autosomal recessive forms of Parkinson's disease?
Parkin
PINK1
DJ-1
125
Autosomal recessive forms of Parkinson's disease at what age do they generally manifest?
Less than 50 years
126
What promotes the formation of euchromatin?
Histone acetylation
127
What is critical for the functioning of clotting factors II, VII, IX, X and the anticoagulative proteins C and S
Vitamin K dependent gamma carboxylation
128
Which enzymatic process is inhibited by Warfarin?
Gamma carboxylation
129
Three key steps for hepatic processing of Bilirubin
Carrier mediated passive uptake of bilirubin at sinusoidal membrane
Conjugation of bilirubin with glucuronic acid
Active biliary excretion of the water soluble nontoxic bilirubin glucoronides
130
Where is conjugation of bilirubin with glucuronic acid done?
In the endoplasmic reticulum
131
What is the importance of ubiquitin that undergoes ATP dependent attachment to other proteins?
Labeling them for degradation
132
What is formed from one molecule of glucose in HMO shunt?
A five carbon sugar, two molecules of NADPH and CO2
133
Types of reaction of HMP shunt
```
Oxidative (irreversible)
Non oxidative (reversible)
```
134
Where do all reactions of HMP shunt occur?
All reaction occur exclusively in the cytoplasm
135
Primary enzymes involved in the non oxidative step of the HMP shunt
Transaldolase and transketolase
136
What is the function of transketolase in HMP shunt?
Transfers two carbon groups between substrates of the HMP shunt
137
When the transketolase transfers two carbon groups between substrates of the HMP shunt, what does it require?
Thiamine pyrophosphate
138
What does transaldolase transfer in the HMP shunt?
Three carbon groups between substrates of HMP shunt
139
What is synthesized from glycolysis intermediates fructose 6 phosphate and glyceraldehyde 3 phosphate with help of transketolase and transaldolase?
Ribose from all cells
140
Where are HMP shunt oxidative reactions active?
In the liver, adrenal cortex, gonads , adipose tissue and erythrocytes
141
In which metabolic pathways does enolase work?
Glycolysis
142
What reaction is catalyzed by enolase?
Catalyzes the conversion of 2 phosphoglycerate to phosphoenolpyruvate
143
Which enzyme catalizes the isomerization of citrate to isocitrate?
Aconitase in TCA cycle
144
Which are two major functions in the metabolism of glucose through the hexose monophosphate shunt?
Production of NADPH as reducing equivalent
| Synthesis of ribose 5 phosphate for nucleotide synthesis
145
In the oxidative portion of HMP shunt what is the first step?
Glucose 6 phosphate Is first converted to 6 phosphogluconolactone producing one molecule of NADPH
146
Which enzyme catalizes Glucose 6 phosphate convertion to 6 phosphogluconolactone?
Glucose 6 phosphate dehydrogenase
147
Which is the rate limiting enzyme for oxidative HMP shunt?
Glucose 6 phosphate dehydrogenase
148
What is the primary designed for non oxidative reaction of the HMP shunt?
To generate ribose 5 phosphate from intermediates of glycolysis
149
Which reaction do erythrocytes use to generate large amounts of NADPH?
HMP shunt
150
What is the purpose of erythrocytes to generate large amounts of NADPH?
To maintain glutathione in a reduced state by the action of gluthatione reductase
151
Which is the importance to maintain reduce glutathione in erythrocytes?
For protection from oxidative damage resulting from oxidant drugs and oxidizing environmental toxins
152
Which is the only major pathway for erythrocytes to generate NADPH?
HMP shunt
153
What is the result of oxidative damage caused to red cells?
Denatured hemoglobin to form insoluble Heinz bodies resulting in erythrocyte destruction in the spleen
154
X linked disorder that results in episodes of hemolysis during oxidative and infective stress
Glucose 6 phosphate dehydrogenase deficiency
155
Which enzyme is deficient in glycogen storage type 1?
Glucose 6 phosphate
156
Which is the biological active form of pantothenic acid?
Coenzyme A
157
In which pathway is pantothenic acid associated?
TCA because it requires coenzyme A
158
How does pantothenic acid becomes coenzyme A?
First actively transported into the cell and then undergoes ATP dependent phosphorylation
159
What is required for the production of mRNA from DNA?
RNA polymerase II
160
Which is the most common seen in cystic fibrosis?
Codon deletion of the phenylalanine at position 508 in the CFTR protein
Frameshift mutation
161
Which are the 2 major processes that mantain plasma glucose between meals?
Glycogenolysis and gluconeogenesis
162
Glycogenolysis
Which is the primary source of glucose for the first 12-18 hours of fasting?
163
Which is the major process used by the body to keep blood glucose levels within the normal range, once hepatic glycogen storage is depleted?
Gluconeogenesis
164
During gluconeogenesis, glucose is formed by...
Lactate, glycerol, and glucogenic aminoacids
165
Can ketone bodies be used to generate glucose?
No
166
What is the result of acetoacetyl CoA to 3 hydroxy 3 methylglutaryl CoA?
Synthesis of cholesterol and ketone bodies
167
First fatty acid produced from acetyl CoA during lipogenesis in the fed state
Palmitic acid
168
How are fatty acids affected during prolonged periods of starvation?
Lipolysis predominates and leads to generation of glycerol and fatty acids
169
In which process does conversion of fructose 6 phosphate to fructose 1,6 biphosphate occur?
During glycolysis
170
Who catalizes the conversion of fructose 6 phosphate to fructose 1,6 biphosphate?
Phosphofructokinase
171
Which is the first step of glycogenolysis?
Breakage of 1,4 glycolysis linkage to form glucose 1 phosphate
172
Which type of hyperlipoproteinemia is dysbetalipoproteinemia?
Type III
173
Which are the primary defects in familial dysbetalipoproteinemia?
ApoE3 and ApoE4
174
Where do we find ApoE3 and ApoE4?
Found on chylomicrons and VLDL that are responsible for binding hepatic apolipoprotein Receptors
175
What happens if there are not ApoE3 and ApoE4?
The liver cannot efficiently remove chylomicrons and VLDL remnants from the circulation, causing their accumulation in the serum and resultant elevations in cholesterol and triglycerides levels
176
What composes mainly chylomicrons?
Triacylglycerol
177
What mainly composes chylomicrons?
Triacylglycerol
178
Where are chylomicrons synthesized?
On the RER and Golgi apparatus of small intestine enterocytes
179
What do chylomicrons have once released from enterocytes?
With only ApoB 48 apolipoprotein
180
What do chylomicrons receive from HDL?
ApoC II and ApoE
181
Where is Apo 100 present?
On LDL
182
Who activates lipoprotein lipase?
ApoC II
183
Who carries ApoC II?
Chylomicrons and VLDL
184
What is the result of ApoC II deficiency?
Hyperchylomicronemia
185
Type of hyperlipoproteinemia cuased by ApoC II deficiency
Type 1
186
Required for esterification of free cholesterol in HDL particles by lecithin- cholesterol acyltransferase (LCAT)
ApoA I
187
What is the result of ApoA I and LCAT deficiency?
Low HDL and increased circulating free cholesterol levels
188
Main function of ApoA I
LCAT activation (cholesterol esterification)
189
Main function of ApoB 48
Chylomicron assembly and secretionby the intestine
190
Main function of ApoB 100
LDL particle uptake by extrahepatic cells
191
Main function of ApoC II
Lipoprotein lipase activation
192
Main function of ApoE 3 and 4
VLDL and chylomicron remnant uptake by the liver cells
193
How many aminoacids are used in protein synthesis?
20
194
Which codons correspond to do amino acid Glicyne?
GGU, GGC, GGA and GGG
195
Many can tRNA anticodons can bind to a few different codons coding for the same aminoacids
Wobble phenomenon
196
Meneaning thar there are more codons (61) than aminoacids(20)
Genetic code "degenerate"
197
For what is each tRNA molecule specific for?
For a given aminoacid
198
What does glucose induced decreased adenylate cyclase activity lead to?
Low intracellular concentrations of cAMP
199
What causes poor binding of catabolite activator protein to the CAP-DNA binding domain?
Low cAMP levels
200
What is the result of poor binding of catabolite activator protein to the CAP-DNA binding domain?
Decreased expression of the structural genes of the lac operon
201
A form of galactosemia that causes a benign disorder characterized by cataracts without hepatocellular manifestations
Galactokinase deficiency
202
What is deficient in classic galactosemia?
Galactose 1 phosphate uridyl transferase (GALT) deficiency
203
Which is the most common form of Galactosemia?
Galactose 1 phosphate uridyl transferase (GALT) deficiency
| Classic galactosemia
204
Clinical manifestations of Galactose 1 phosphate uridyl transferase (GALT) deficiency
Vomiting, lethargy and failure to thrive soon after feeding begun
205
When do Galactose 1 phosphate uridyl transferase (GALT) deficiency manifest?
After initiation of breast-feeding
206
What is the result of deficiency of galactokynase?
Elevation of galactose levels
207
What happens to excess circulating galactose?
Is converted to galactitol by aldolase reductase and to galactonic acid by galactose oxidase
208
What happens to increased levels of galactonic acid and galactitol?
Galactonic acid can be metabolized by HMP shunt, galactitol accumulates in cells
209
Who is responsible for the formation of cataracts in patients with galactokinase deficiency?
Excess Galactitol
210
Which enzyme catabolizes the conversion of galactose to galactitol?
Aldolase reductase
211
This enzyme deficiency results in hereditary fructose intoleranse
Aldolase B
212
When do patients with aldolase B deficiency become symptomatic?
After ingestion of sucrose and fructose containing food for the first time, typically during infancy
213
Which enzyme converts glucose 6 phosphate to glucose?
Glucose 6 phosphatase
214
Last step in production of glucose from gluconeogenesis and glycogenolysis
Conversion of glucose 6 phosphate to glucose by Glucose 6 phosphatase action
215
Disease caused by Glucose 6 phosphatase deficiency
Glycogen storage disease type 1, von Gierke's disease
216
Clinical manifestations of von Gierke's disease
Hypoglycemia, lactic acidosis and hypertriglyceridemia
217
How are porphyria classified?
Hepatic or erythropoietic
218
What is the purpose of Heme synthesized in the liver?
For use in the cytochrome p450 enzyme system
219
Purpose of heme in the bone marrow
Is generated for hemoglobin use
220
From what does porphyria manifest?
From accumulation of precursor of porphyrins in the blood, tissues and urine
221
Drugs that may precipitate acute attacks of intermittent hepatic porphyria
Phenobarbital, griseofulvin, and phenytoin
222
What else can induce an acute attack of porphyria?
Alcohol and a low caloric diet
223
How do drugs, alcohol and low caloric diet may precipitate porphyria symptoms?
By decreasing the hepatic concentration of heme
224
What is the consequence of decreasing the hepatic concentration of heme?
Causes an increase in Hepatic ALA synthase activity
225
What is the result of increased Hepatic ALA synthase activity?
Leads to increased formation of delta aminolevulinic acid and porphobillinogen
226
So... What is the result of reduction in heme synthesis?
Leads to increased formation of delta aminolevulinic acid and porphobillinogen
227
How is the diagnosis of acute intermittent porphyria done?
By demonstrating elevated delta aminolevulinic acid and porphobillinogen during acute attacks
228
Who inhibits ALA dehydratase and ferrochelatase?
By lead
229
What is the result of decreased in glucuronyl transferase?
Results in unconjugated hyperbilirubinemia
230
What is the effect of heme to ALA synthase?
Inhibits it
231
Highly conserved DNA sequence, usually about 180 nucleotides n lenght
A homebox
232
What is the function of homebox?
Typically Code for DNA binding transcription factors which alter the expression of genes involved in morphogenesis
233
What happens to pyruvate when inadequate of our presented in tissues?
Pyruvate is converted to lactate by the enzyme lactate dehydrogenase
234
What is the purpose to generate lactate?
To generate the NAD+ from NADH+
235
What are the results of increased lactate levels?
Metabolic acidosis, and will attempt to compensate by causing a respiratory alkalosis
236
In the presence of oxygen, what does pyruvate preferentially becomes?
Converted to acetyl coenzyme A
237
Who converts pyruvate to acetyl coenzyme A?
Pyruvate dehydrogenase
238
Which is the final step of glycolysis?
Is the conversion of phosphoenolpyruvate to pyruvate
239
Who converts phosphoenolpyruvate to pyruvate?
Pyruvate kinase
240
Which enzyme manage the conversion of 2 phosphoglycerate to phosphoenolpyruvate?
Enolase
241
Branched chain amino acids
Leucine, isoleucine, valine
242
A disorder characterized by defective breakdown of branched chain amino acids
Maple syrup urine disease
243
Which enzyme is affected in Maple syrup urine disease?
Branched chain alpha keto acid dehydrogenase
244
When does maple syrup urine disease usually manifest?
Within the first few days of life
245
Which type of diet do maple syrup urine disease should have?
Dietary restriction of branched chain amino acids, such as leucine
246
What diseases may lead by defective breakdown of tyrosine?
Hypertyrosinemia or alkaptonuria
247
What type of diet is recommended for patients with alkaptonuria?
Diet low in tyrosine and phenylalanine
248
Which enzyme is defective in hypermethioninemia?
Methionine adenosyltransferase
249
Which supplementations are required for treatment of classic homocystinuria?
Methionine restriction and cysteine supplementation
250
This illness classically results in dystonia and poor feeding as well as the mapple syrup scent
Maple syrup urine disease
251
What is Pompe disease?
Glycogen storage disease type II
252
Which enzyme deficiency causes Glycogen storage disease type II?
Acid alpha glucosidase (acid maltase)
253
Mechanism of action of Acid alpha glucosidase (acid maltase)
Breaking down glycogen within the acidic environment of lysosomes
254
Classic form of Pompe disease
Marked cardiomegaly, severe generalized hypotonia, macroglossia and hepatomegaly
255
Key distinguish of glycogen storage disease type II
Muscle biopsy shows Glycogen in lysosomes
256
Glycogen accumulation within lysosomal vacuoles is specific for...
Acid alpha glucosidase (acid maltase)
257
What does pyruvate kinase deficiency cause?
Chronic hemolytic anemia, splenomegaly, and iron overload as a result of impaired erythrocyte survival
258
A disease characterized by hemorrhages, subperiosteal hematomas, bleeding into joint spaces, gingival swelling, secondary periodontal infection, anemia, hyperkeratotic papular rashes, impaired wound healing and weakend immune response to local infections
Scurvy
259
Which is one of the most important functions of ascorbic acid?
Its activation of prolyl and lysyl hydroxylase precursors, both of which are necessary for the hydroxylation of procollagen
260
What characterizes zinc deficiency?
Acrodermatitis enteropathica, growth retardation and infertility
261
Which cells can't utilize ketone bodies for energy?
Erythrocytes and other cells lacking mitochondria
262
These cells although they have mitochondria, they can't utilize ketone bodies
Hepatocytes
263
Why hepatocytes can't use ketone bodies?
Because they enzyme succinyl CoA acetoacetate CoA transferase (thiophorase)
264
Which is the most common cause of xeroderma pigmentosum?
Absence of UV specific endonuclease
265
Which is the function of UV specific endonuclease?
Recognizes distortions in the structure of DNA caused by thymine dimers, and subsequently excises stretches of single stranded DNA which contain these defects
266
Photosensitivity, poikiloderma, and hyperpigmentation in sun exposed areas and also posses a markedly increased risk of developing skin cancers
Xeroderma pigmentosum
267
Who is the only one that has 5' to 3' exonuclease activity?
DNA polymerase I
268
Which is the function of DNA polymerase I?
Remove the RNA primer (3' hydroxyl group)
269
Once Removed the RNA primer (3' hydroxyl group) by DNA polymerase I, who uses it to initiate DNA replication?
DNA polymerase III
270
What else does DNA polymerase I do?
Performs exonuclease excision and repair of damage to parent DNA
271
What is the purpose of 5' to 3' activity of DNA polymerase I?
Used to remove the RNA primer (which initiates DNA polymerizarion) and to remove damaged DNA
