Biochem Final Key things

105 Questions

Match each disease to its disrupted enzyme

Phenylketonuria = Phenylalanine deficiency: infant musty odor Alkaptonuria = Homogentisate Oxidase: Black urine and bones Maple Syrup Disease = Branched chain amino acids (valine + Isoleucine) Tyrosinemia I = Fumarylacetoacetate Hydrolase: Death in 1 year; cabbage body odor

Match each disease to its cause

Tyrosinemia II = Tyrosine Aminotransferase disruption Hyperhomocysteinemia = Mutation in Serine Hydroxymethyltransferase; mutated cystathione-b-synthase Transient Tyrosinemia = Immature hydroxyphenylpyruvate enzymes, Vitamin C deficiency, and Elevated intake of tyrosine and phenylalanine Folate Deficiency = Elevated uracil in DNA; reduced dTTP

Which of the following can donate carbons?

Glycine

What is decreased in Hyperhomocysteinemia?

B12/ B6

What is not one of the elements needed for purine synthesis

Valine

What reaction requires tetrahydrobiopterin?

Phenylalanine to tyrosine

Which of the following does not correctly describe the metabolism of serine?

Generates cystathionine when combined with S-adenosylmethionine

Which of the following is not needed to generate cysteine?

Biotin

Which of the following spontaneously forms a ring structure?

Glutamate semialdehyde

Which of the following can generate glycine?

Threonine

An increase of which class of amino acids leads to maple syrup urine disease?

Branched chain amino acids

Which of the following is not correctly matched?

Phenylketonuria and black bone

Which of the following is the most abundant tetrahydrofolate species in the human body?

N5-methyl-FH4

Which unique feature is found in Vitamin B12?

Presence of cobalt

During a vitamin B12 or folate deficiency, which organ can still recycle Methionine from Homocysteine?

Liver

Which of the following is not correctly matched?

Iron storage and transferrin

How many nuclei are found in a megakaryocyte that is actively releasing platelets?

Which of the following terms describes the platelet membrane?

Canalicular

Which of the following is not an accurate statement of von Willebrand factor?

Stabilizes clotting factor VII in the blood

Match each degradation pathway to its enzymes and diseases

Phenylalanine = Enzymes: Phe hydroxylase (PAH), homogentisate oxidase; Disease: PKU classic alcaptonuria Tyrosine = Enzymes: Fumarylacetoacetate hydrolase, tyrosine aminotransferase; Diseases: Tyrosinemia I & II Methionine = Enzymes: Cystathionase, Cystathionine- beta-synthase; Diseases: Cystathioninuria, Homocysteinemia Glycine = Glycine transaminase (Gly-> Oxalate); Disease: Oxaluria type 1

Match each group of amino acids to what they produce

Pyruvate = Alanine, Cysteine, Glycine, Serine, Threonine, Tryptophan Acetyl-CoA via acetoacetyl- CoA = Leucine, Lysine, Phenylalanine, Tryptophan Acetyl-CoA directly = Isoleucine, Leucine, Threonine, Tryptophan Alpha-ketoglutarate = Arginine, Glutamate, Glutamine, Histidine, Proline

Match each group of AA to what they produce

Succinyl- CoA = Isoleucine, Methionine, Threonine, Valine Fumarate = Phenylalanine, Tyrosine Oxaloacetate = Asparagine, Aspartate N/A = N/A

Which of the following is critical in the activation of platelets?

Thrombin

Which of the following is important in the extrinsic clotting cascade and not found in the intrinsic pathway?

Tissue factor

SERPIN drugs would not affect which of the following enzymes?

Factor XIII

Salvage pathways are important for which of the following?

Adenine

Which of the following donates a carbon to help form purines?

Carbon dioxide

Which of the following amino acids in its entirety is included in purines?

Glycine

Which of the following is formed first during purine and pyrimidine de novo synthesis?

RNA bases

Which of the following catalyzes the commitment step towards purine synthesis

Glutamine PRPP amidotransferase

Which of the following provides necessary energy for the formation of GMP?

ATP

Which of the following is not an allosteric inhibitor of purine synthesis?

UMP

Which of the following is the target of allopurinol?

Xanthine oxidase

The following can convert adenosine to AMP directly?

Adenosine kinase

The following can convert guanine to GMP directly

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

Deficiency of which of the following can lead to severe combined immunodeficiency?

Adenosine deaminase

Which of the following catalyzes the commitment step of pyrimidine synthesis? And where in the cell does the synthesis occur?

Carbamoyl phosphate synthetase II and in the cytosol

What is the first pyrimidine generated in denovo synthesis?

UMP

Which of the following is an allosteric activator of carbamoyl phosphate synthetase II?

PRPP

Which of the following is not a peptide hormone

Cortisol

Which of the following will negatively affect the release of growth hormone ONLY from the anterior pituitary?

Growth hormone releasing inhibitory hormone

What is the precursor for dopamine

Tyrosine

Which of the following is the active form of thyroid hormone?

Which of the following can activate thermogenin through norepinephrine?

Thyroid hormone

Which of the following is not correctly matched?

Fetal hemoglobin alpha 2 beta 2

Which of the following is not a correct statement about hemoglobin S and C?

Hemoglobin S protects from malaria whereas hemoglobin C does not

Which of the following terms is associated with normal red blood cell morphology?

Normochromic

Which pathway produces the most ATP in the red blood cell

Glycolysis

The hexose-monophosphate shunt is analogous to which of the following pathways?

Pentose Phosphate Pathway

2, 3 bisphosphoglycerate is generated from which glycolysis intermediate?

1,3 bisphosphoglycerate

What is the purpose of cytochrome b5 reductase

Reduce ferric

Which of the following is a precursor of heme?

Glycine

Zinc can inhibit heme synthesis by incorporating into which compound?

Protoporphyrinogen IX

What is the average lifespan of the red blood cell?

120 days

Which of the following is not a correct statement about the degradation of bilirubin?

Yellow sclera associated with hypobilirubinemia

How is iron transported in the blood?

As transferrin

In red blood cell structure, which of the following proteins is a transmembrane protein?

Band 3 protein

Which of the following is a negative regulator of platelet activity?

PGI2

Which of the following clotting factors is not dependent on Vitamin K?

XII

Which of the following is not activated by thrombin?

Factor IX

Match each structure to its action

GPIA = Binds collagen GPIB = Binds von Willebrand factor PKC = Release granules ADP release = Attractant (recruits more platelets)

Match each item to its action

GPII A + GPII B = Bind fibrinogen and induce aggregation (inhibited by rattlesnake venom) Stellate cells = Store Vitamin A Alpha actin and myosin (heavy chains) = ATPase activity Alpha actin and myosin (light chains) = Calcium

Match each structure to its action

CYP34A = Grapefruit inhibits; metabolizes most drugs CYP2D6 = Codeine, antidepressants, opioids, etc. CYP2E1 = Alcohol, tylenol, vinyl chloride/ Binds protein and DNA CYP1A1 = Enhances aflatoxin B1, fluvoxamine metabolism

In damaged tissue, what does vonWilibrand bind during platelet adhesion?

Collagen

Which of the following is an important attractant for platelets and is released by activated platelet?

ADP

Which of the following factors can thrombin directly activate?

Which of the following blood clotting factors is part of the intrinsic but not extrinsic pathway?

Which of the following clotting cascade factors is a direct target for activated protein C?

VIII

The amount of which of the following determines the half life of the red blood cell?

Glucose-6-phosphate dehydrogenase

What is the reducing agent used by cytochrome b5 reductase?

NADH

Which of the following is a precursor for heme synthesis?

Succinyl-CoA

Which of the following is the regulated step of heme synthesis?

delta-aminolevulinic acid synthase

When breaking down heme, what is the fate of the globin portion of the hemoglobin molecule?

Precursor for amino acids

Which of the following cell supports neuron growth and development?

Astrocyte

Which of the following is a ciliated cell that secretes cerebrospinal fluid (CSF)?

Ependymal cell

Which of the following is another name for growth hormone releasing hormone?

Somatocrinin

Which of the following is NOT a trigger for the release of growth hormone?

Decrease in blood amino acids

What form of thyroid hormone is stored in the colloid space?

Both T3 and T4

What is the fate of RNA synthesis in a cell in the presence of cortisol signaling?

Decreases synthesis

What is the stored form of folate in the body?

5-methyl THF

What of the following is the most oxidized form of tetrahydrofolate?

N10-formyl THF

Which species of THF can donate a methyl group to UMP to generate TMP?

N5, N10-Methylene THF

Which of the following can donate carbons to form a purine ring structure?

N10-formyl THF

What is the most abundant source of THF in the body?

Serine metabolism

In a patient with a Vitamin B12 deficiency, what is the most common cause in the United States?

Intrinsic factor disorder

Which of the following does not provide a nitrogen to a purine ring structure?

Alanine

What is the activated ribose called?

5-phosphoribosyl-1-pyrophosphate

Orotic Aciduria is formed during which of the following synthesis pathways?

Pyrimidine

Which of the following characteristics of cytochrome p450 enzymes is correct?

They all oxidize the substrate on which they act

Drinking grapefruit juice while taking statins can lead to potentially devastating side effects. This is caused by a component of grapefruit juice doing which of the following?

Inhibiting the inactivation of statins

Which of the following metabolizes Aspergillus Aflatoxin B1

CYP2A1

Which of the following metabolizes acetaminophen?

CYP2E1

Which of the following metabolizes vinyl chloride?

CYP2E1

Which of the following metabolizes opioids?

CYP2D6

Which of the following is the most abundant in the liver and gut?

CYP3A4

Which of the following has ATPase activity?

Alpha actin

This molecule blocks actin and myosin from interacting?

Troponin I

This is a product that forms spontaneously in creatine metabolism

Creatinine

Match each cell to its function

Hepatocyte = Metabolically necessary Endothelial cells = Leaky Kupffer cells = Macrophages Pit cells = Natural killer cells

Match each cell to its function

Tropomyosin = Binds actin in the presence of calcium; makes actin available to interact with myosin Troponin T = Binds tropomyosin Troponin C = Binds calcium Troponin I = Blocks actin and myosin interaction

Match each item to whether it can get in or out of the blood brain barrier

Must get in = Essential AA, Essential FA, CO2, H2O, O2 Must not get in or out = Non-essential FA, Non-essential AA, Alanine Must get in = Glucose, Ketone bodies, Insulin, IGF, Vitamine Must not get in or out = Glycine, Proline, GABA

In the biosynthesis pathways for heme, creatine, and guanine, which one of the following amino acids directly provides carbon atoms that appear in the final product?

Glycine

Which of the following is the most important inhibitory neurotransmitter of the CNS?

GABA

Which of the following is the most important excitatory neurotransmitter of the CNS?

Glutamate

Which of the following must not cross from the blood and into the brain?

Glycine

Study Notes

Phenylketonuria: Disrupted enzyme - Phenylalanine Hydroxylase
Alkaptonuria: Disrupted enzyme - Homogentisate 1,2-Dioxygenase
Hyperhomocysteinemia: Decreased - Methionine
Maple Syrup Urine Disease: Increased - Branched-Chain Amino Acids

Reaction requiring Tetrahydrobiopterin (BH4): Phenylalanine Hydroxylase
Vitamin B12 unique feature: Ability to transfer methyl groups
Vitamin B12 or Folate deficiency: Liver can still recycle Methionine from Homocysteine
Most abundant Tetrahydrofolate species: 5-Methyl-THF

Platelet Structure and Function

Megakaryocyte features: Multiple nuclei
Platelet membrane feature: Phospholipid Bilayer
Inaccurate statement about von Willebrand factor: Not involved in platelet adhesion
Critical for platelet activation: Collagen
Extrinsic clotting cascade component: Tissue Factor
SERPIN drugs do not affect: Plasminogen Activator Inhibitor-1

Amino Acid Metabolism

Cysteine generation: Serine and Homocysteine
Glycine generation: Choline, Serine, and Threonine
Purine synthesis donors: Glycine, Aspartate, Glutamine, and CO2
Inosine Monophosphate (IMP) synthesis: First step in purine synthesis

Coagulation Cascade

Unique feature of Vitamin K: Essential for clotting factor synthesis
Thrombin-activated factors: Factor VIII, Factor XI, and Factor V
Intrinsic pathway component: Factor IX
Activated Protein C target: Factor Va
Platelet attractant: Thromboxane A2

Red Blood Cell Structure and Function

Red Blood Cell membrane protein: Glycophorin
Negative regulator of platelet activity: Prostacyclin
Hemoglobin S and C incorrect statement: Not associated with sickle cell anemia
Red Blood Cell morphology term: Discocyte
Most ATP-producing pathway: Glycolysis

Heme Synthesis

Heme precursor: Succinyl-CoA and Glycine
Zinc incorporation compound: Protoporphyrin IX
Red Blood Cell lifespan: 120 days
Bilirubin degradation statement: Not degraded by the liver
Iron transportation protein: Transferrin
Cytochrome b5 reductase function: Reduces methemoglobin

Neurobiology

Neuron growth and development supporter: Astrocytes
Cerebrospinal fluid (CSF) secreter: Choroid Plexus
Growth Hormone Releasing Hormone (GHRH) alternative name: Growth Hormone Releasing Factor (GHRF)
Non-trigger for Growth Hormone release: High blood glucose

Thyroid Hormone and Cortisol

Stored Thyroid Hormone form: Triiodothyronine (T3)
Cortisol signaling effect: Inhibits RNA synthesis

Folate Metabolism

Stored Folate form: Methyl-THF
Most oxidized form of THF: 10-Formyl-THF
Methyl donor species: 5-Methyl-THF
Vitamin B12 deficiency common cause: Inadequate intrinsic factor production
Non-nitrogen donor to purine ring: Aspartate
Activated ribose: Phosphoribosyl Pyrophosphate (PRPP)

Drug Metabolism

Grapefruit juice interaction: Inhibits CYP3A4
Aspergillus Aflatoxin B1 metabolizer: CYP3A4
Acetaminophen metabolizer: CYP2E1
Vinyl chloride metabolizer: CYP2E1
Opioids metabolizer: CYP2D6
Most abundant enzyme in liver and gut: CYP3A4
ATPase activity exhibitor: CYP3A4

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