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rere_girl4ever
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Tetrahydrobiopterin (BH4) is used as a cofactor in the synsthesis of?
- Tyrosine
- Dihydroxyphenylalanine
- Serotonin
- Nitric oxide
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5-hydroxytryptamine is also known as?
Serotonin
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Another name for serotonin is?
5-hydroxytryptamine
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Where is serotonin synthesized from? What are the necessary cofactors?
- Serotonin is synthesized from Tryptophan.
- Cofactors: B6 and Tetrahydrobiopterin
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What are the causes of Phenylketonuria?
- 1. Deficiency of phenylalanine hydroxylase
- 2. Lack of Tetrahydrobiopterin (due to dihydrobioptein reductase deficiency)
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How is G-aminobutyrate synthesized?
- Glutamate is converted to G-aminobutyrate (GABA) by Glutamate decarboxylase.
- B6 is used as a cofactor.
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What is the function of Glutamate decarboxylase?
Converts Glutamate to GABA (G-aminobutyrate)
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Vitamin B12 is needed in the conversion of?
- 1. Homocysteine to Methionine (by homocysteine methyltransferase)
- 2. Methylmalonyl CoA to Succinyl-CoA (by methylmalonyl-CoA mutase/ ISOMERASE)
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What is pantothenic acid?
B5
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What is the active form of pantothenic acid?
Coenzyme A
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Pantothenic acid is an essential cofactor in which reactions?
- In acetylation recations.
- Oxaloacetate ⇨ Citrate by Acetyl-CoAα-ketoglutarate ⇨ Succinyl-coA by α-ketoglutarate dehydrogenase
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This structure produces ribosomal RNA.
- Nucleolus

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What is the function of the nucleolus?
Site of ribosomal RNA synthesis
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In this pathology, vesicles and blisters form on sun exposed areas. What is the deficient enzyme? What is the accumulated substrate?
- Deficient enzyme: Uroporphyrinogen decarboxylase
- Accumulated substrate: Uroporphyrin (tea colored urine)
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Deficiency of Uroporphyrin decarboxylase results in?
Porphyria cutanea tarda
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What is the function of Uroporphyrinogen decarboxylase?
Converts Uroporphyrinogen III to Coproporphyrinogen III
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What is the function of δ-aminolevullinic acid synthase?
- Converts Glycine + Succinyl-CoA to δ-aminolevulinic acid
- B6 is a cofactor
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A deficiency of δ-aminolevulinic acid synthase results in?
- Sideroblastic anemia
- Microcytic hypochromic
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What is the most abundant amino acid in the collagen molecule?
- GlycineIt occurs in at least every third amino acid postition.
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What is the amino acid formula of collagen?
(Gly-X-Y-)333
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What are the amino acids designated X and Y in the amino acid sequence of collagen (Gly-X-Y)333?
Many of the amino acids designated X and Y are PROLINE residues.
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What amino acid is essential in the formation of the alpha helix?
Proline
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What is Type II glycogen storage disease?
Pompe disease
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What enzyme is deficient in Pompe disease?
Lysosomal α-1,4 glucosidase (acid maltase)
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A deficiency of lysosomal α-1,4 glucosidase is characteristic of?
- Pompe disease
- Acid maltase
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A deficiency of acid maltase is characteristic of?
Pompe disease
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In this glycogen storage disease, polysacchardides (glycogen) accumulates within lysosomes.
Pompe disease
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Describe the clinical presentation of Pompe disease.
- Hepatomegaly
- CARDIOMEGALY
- Macroglossia
- Hypotonia
- Mental retardation
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Describe the lab/ microscopic findings in Pompe disease
- Normal blood sugar levels
- Polysaccharide/ glycogen accumulation in lysosomes
- NORMAL glycogen structure
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Which cells cannot use ketone bodies and why?
- Erythrocytes- lack a mitochondria
- Hepatocytes- lack the enzyme succinyl CoA-acetoacetate CoA transferase (thiophorase) which is required to convert acetoacetate to acetoacetyl CoA
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Which cells use ketone bodies for energy?
- 1. Skeletal muscles
- 2. Cardiac muscles
- 3. Renal cortex
- 4. Brain (during starvation)
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The 3' hydroxyl group necessary for the initiation of DNA synthesis is provided by which enzyme?
Primase- provides 3' hydroxyl group
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What is the function of phenylalanine hydroxylase?
Converts phenylalanine to tyrosine
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What is the function of tyrosinase?
Converts tyrosine to melanin
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What is the major amino acid resposible for transferring ammonia to the liver for disposal?
Alanine
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How is ammonia disposed?
- 1. Alanine transports ammonia (NH3) to the liver
- 2. In the liver, alanine is transaminated by alanine aminotransferase to pyruvate
- 3. The NH3 is transferred to α- KETOGLUTARATE to form GLUTAMATE
- 4. Glutamate is further metabolized by the enzyme glutamate dehydrogenase, which liberates free ammonia and regenerates α-ketoglutarate.
- 5. Ammonia then enters the urea cycle to form urea, which is subsequently excreted in the urine.
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What is the use of enteropeptidase?
Converts trypsinogen to trypsin
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This enzyme is essential for the conversion of trypsinogen to trypsin
Enteropeptidase/ Enterokinase
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This condition causes lipase deficiency.
- Chronic pancreatitis
- This leads to poor fat absorption and steatorrhea (foul smelling bulky stools containing undigested fat)
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What are the chronic toxicities of Vitamin A overuse?
- Alopecia
- Dry skin- SCALINESS
- Hepatic toxicity/ hepatomegaly
- PSEUDOTUMOR CEREBRI- Papilledema- swelling of optic disc due to ⇧intracranial pressue.
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Pseudotumor cerebri is associated with which vitamin use?
Vitamin A overuse
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What are the cofactors required by Pyruvate dehydrogenase in the conversion of Pyruvate to acetyl CoA?
- 1. B1: Thiamine pyrophosphate
- 2. B2 (Riboflavin): FAD
- 3. B3 (Niacin): NAD
- 4. B5 (pantothenic acid): CoA
- 5. LIPOIC ACIDNOTE: α-ketoglutarate complex requires the same as the pyruvate dehydrogenase complex.
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Vomiting, rice-water stools and garlic breath are diagnostic of?
Arsenic poisoning- inhibits lipoic acid
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This substance inhibits lipoic acid. What are the manifestations?
- Arsenic poisoning
- Findings: Vomiting, rice-water stools, garlic breath
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What are the cofactors required by the α-ketoglutarate dehydrogenase complex?
- 1. B1: Thiamine pyrophosphate
- 2. B2 (Riboflavin): FAD
- 3. B3 (Niacin): NAD
- 4. B5 (pantothenic acid): CoA
- 5. LIPOIC ACID
NOTE: The pyruvate dehydrogenase complex requires the same cofactors as the α-ketoglutarat dehydrogenase complex.
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What causes methylmalonic acidemia /aciduria?
Results from a defect in the ISOMERIZATION reaction that transforms methylmalonyl CoA to Succinyl CoA by methylmalonyl-CoA mutase (isomerase).
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This enyme converts methylmalonyl-CoA to Succinyl-CoA.
Methylmalonyl-CoA mutase a.k.a ISOMERASE
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What is the function of the enzyme isomerase?
- Converts methylmalonyl-CoA to Succinyl-CoA.
- A.k.a Methylmalonyl-CoA mutase
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Where is Uracil found?
RNA
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Which enzyme involved in DNA synthesis catalyzes the formation of RNA strands?
Primase
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Which cells are rich in smooth endoplasmic reticulum?
- Steroid producing cells.
- Liver hepatocytes
- Adrenals
- Gonads
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What is the function of the COP II coated transport vesicles?
Transports proteins from the RER to the Golgi apparatus.
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Describe the structure of a transmembrane domain.
- Spans the membrane
- Composed of alpha helices with approximately 20 hydrophobic amino acid residues such as valine, alanine, isoleucine, methionine and phenylalanine.
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These drugs inhibit formation of the initiation complex,
- Aminoglycosides
- Gentamycin
- Neomycin
- Amikacin
- Tobramycin
- Streptomycin
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This drug interferes with the binding of aminoacyl-tRNA to the A site.
Tetracycline, Doxycycline, Minocycline
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What is the MOA of Doxycycline?
Bind to 30s ribosome and prevents the binding of aminoacyl-tRNA to the A site.
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What is the MOA of Minocycline?
Bind to the 30s ribosome and prevents the binding of aminoacyl-tRNA to the A site.
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What is the MOA of Tetracycline?
Binds to the 30s ribosome and prevents the binding of aminoacyl-tRNA to the A site.
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Describe the MAP kinase pathway.
- 1. Insulin/ Growth factors bind to tyrosine kinase causing autophosphorylation of the receptor.
- 2. Phosphorylated tyrosine kinase reacts with SH2 domain proteins and SOS protein leading to RAS activation.
- 3. Active form of RAS is bound to GTP.
- 4. Ras activtes Raf kinase.
- 5. Raf kinase activates MAP kinase.
- 6. Activated MAP kinase enters the nucleus to influence gene transcription.
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Lipoic acid is a cofactor for which mitochondiral enzymes?
- Pyruvate dehydrogenase
- α-ketoglutarate dehydrogenase
- Branched chain ketoacid dehydrogenase
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Describe the DNA of the mitochondia.
Small, circular chromosomes
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This cellular organelle codes for proteins, tRNA and rRNA.
Mitochondria
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Label the heterochromatin and euchromatin.
- Euchromatin- less condensed, transcriptionally active
- Heterochromatin- condensed, transcriptionally inactive

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Describe the metabolism of Arginine.
- Arginine is metabolized to Urea and Ornithine.
- H2O is given off in this process.
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Describe the presentation of Wet beri beri.
- High output congestive heart failure and neurological symptoms
- (dilated cardiomyopathy)
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Anti-snRNP antibodies are present in which disease?
Mixed connective tissue disease
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Which autoantibodies are present in mixed connective tissue disease?
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Anti-U1 RNP autoantibodies are present in which disease?
Mixed connective tissue disease
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What is the pathology seen below?
Centriacinar emphysema
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Label the diagram below.
- 1. Pulmonary artery (right side)
- 2. Lung (right side)
- 3. Superior vena cava.
- 4. Ascending thoracic aorta.
- 5, Pulmonary trunk.
- 6, Pulmonary vein (left side).
- 7, Pulmonary artery (left side).
- 8, Scapula.
- 9, Rib
- 10, Lung (left side).
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Test A is newly available for diagnosing myocardial infarction. In a recent study, the results of test A (compared to a gold standard diagnosis of MI were as follows:
The patient has a positive result on test A. Assuming his pre-test probability is equivalent to the prevalence of MI in the study, what is the probability that the patient has an MI?
- The PPV of a diagnostic test answers this question: Given a positive test result, what is the probability that the patient has the disease?
- PPV= 200/ 200+50
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Label the diagram of the heart below.
- a- left ventricle
- b- right ventricle
- c- right atrum
- d- left atrium
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What is the function of the Nef gene in HIV infection?
Nef decreases expression of MHC class I proteins on the surfaces of infected cells.
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In HIV infection, this viral gene decreases expression of MHC class I proteins on the surfaces of infected cells.
Nef
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What is the function of the Tat gene in HIV infection?
Tat plays a role in viral replication.
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What is normal PaCO2?
33-45mmHg
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What is normal bicarbonate?
22-28 mEq/L
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Describe the acid/base physiology of Salicylate / Aspirin intoxication.
- 1. Respiratory alkalosis- due to stimulation of medullary respiratory center ⇛ HYPERVENTILATION
- 2. Metabolic acidosis- due to accumulation of organic acids due to inhibition of TCA ect.
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Secretion from this sweat gland can become malodorous secondary to bacterial decomposition on the skin surface.
Apocrine
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