Term
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Definition
Chemicals derived from tyrosine. Mnemonic: Tyred Cat. |
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Term
| One key catecholamine is L-Dopa, a precursor of dopamine. It is used as a treatment for what disease? Why? |
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Definition
| L-Dopa is administered to Parkinson's Disease patients because it can cross the blood-brain barrier where it can be transformed into dopamine (deficient in Parkinson's patients). |
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Term
| Is there any truth to the rumor that tryptophan from turkey makes one drousy? |
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Definition
| Some. Tryptophan is a precursor in the synthesis of seratonin, a neurotransmitter which does function to depress the CNS. |
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Term
| The neurotransmitter GABA is unique in that it is also technically an amino acid. From which AA is it derived? |
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Definition
GABA is derived from Glutamate. BONUS: The reaction uses PLP, a common AA synthesise coenzyme. |
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Term
| Which one is it: Histidine is synthesized from Histamine OR the opposite? |
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Definition
-Histidine is upstream from histamine (it's alphabetical). BONUS: Why are histamine antagonists used to treat duodenal ulcers? Because histamine, in addition to playing a role in the allergen response, affects gastric HCL synthesis. |
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Term
| In the first step of heme synthesis, a 4C unit combines with a 2C unit. What are these two molecules? |
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Definition
4C=Succinyl Coa 2C=Glycine |
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Term
| In the second step of heme synthesis, how many aminolevulinates are used to create the four porphobilogen molecules? |
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Definition
| Answer: 8. There is a 2:1 ratio; two aminolevulinates are combined to form a ring. |
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Term
Linear tetrapyrrole molecules are cyclized to form uroporphyrinogen during an intermediate step of heme synthesis. Theoretically this should create a symmetrical ring structure, but biologically these are not found. What happens? |
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Definition
Uroporphyrinogen III cosynthase, a key enzyme in the reaction, has isomerase activity. It reverses an A-, P- branch on the molecule to erase the symmetry (there are four A-,P- locations). REMEMBER: The A-, P- chains are always reversed at the 9-o'clock position (12, 3, and 6 will read A-P, A-P, A-P). |
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Term
What are the eventual fates of the A- and P- chains on the uroporphyrinogen ring? BONUS: What will happen to the intracellular N-H groups? What does this achieve? |
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Definition
The A- chains will be methylated. Vinyl groups will replace two of the P- chains; the other two P- chains will remain. BONUS: Two of the hydrogens will be removed; this allows for coordinate bonding with Fe. |
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Term
| How are aromatic rings like hemes degraded? |
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Definition
| They are oxidized (in the case of heme, by the aptly titled enzyme heme oxidase). |
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Term
Bilirubin is a byproduct of heme degradation. Why do we test for it? BONUS #1: What color is it? BONUS #2: What is its function? |
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Definition
Tests for bilirubin content in urine are done to examine liver function. Bilirubin isn't water soluble; it has to be transformed into urobilinogen to be excreted. This is done in the liver, so no bilirubin should be present in the urine if the liver is functioning normally. BONUS #1: Bilirubin is the yellow phase of bruising (erythrocytes are being degraded) and contributes the yellow tinge to urine. BONUS #2: It is speculated that bilirubin is a potent antioxidant, as it can be oxidized back into its progenitor in heme degradation, biliverdin (reponsible for green bruising). |
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Term
| A clear sign of jaundice is a yellowing of the eyes and skin. Bilirubin is yellow in color...could there be a connection? |
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Definition
Yes. The Z,Z-isomer of Bilirubin is highly insoluble and must be converted to the more soluble E,Z- and E,E- forms so that it can be excreted in the urine. In children and adults with compromised hepatic function, the enzyme required for adding the two glucauronate groups necessary to create the soluble forms is missing. This causes a build-up of bilirubin, giving the eyes and skin the characteristic coloration. Bili lights are used for treatment, as they can isomerize the insoluble Z,Z- forms. |
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Term
| Dr. Smith lectured on two Porphyria Diseases. The first is Congenital Erythropoetic Porphyria. Describe its pathophysiology and symptoms. |
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Definition
Pathophysiology: A deficiency in the cosynthase required for A-,P- group isomerization (uroporphyrinogen III). The symmetric porphyrins build up in tissues and red blood cells. Symptoms: Red urine (iron excretion), strong red fluorescence in teeth, and sensitivity to light. BONUS: It is thought that some of these individuals were accused of being vampires. |
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Term
| Dr. Smith lectured on two Porphyria Diseases. The second is Acute Intermittent Porphyria. Describe its pathophysiology and symptoms. |
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Definition
Pathophysiology: A deficiency in porphobilinogen deaminase (it creates the linear tetrapyrrole that will cyclize to create the basic heme structure). Symptoms: Elevated levels of porphobilinogen and aminolevinulate lead to severe abdominal pain and compromised neurological function. BONUS: This was the disease featured in the film "The Madness of King George" (III). It is known as "Intermittent" because the neurological compromise features bouts of mania. |
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Term
| Glutathione is a molecule that requires an energy intensive fusion of Glu-Cys-Gly. What is its fuction? |
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Definition
| It is a reducing buffer in cells that acts as an antioxidant. The oxidized form is returned to its functioning reduced state via a reductase enzyme. |
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Term
| Why is creatine phosphate used as an energy storage system in the muscles? |
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Definition
Creatine Phosphate is used as a buffer system to maintain an appropriate ATP:ADP ratio. Creatine-P + ADP <-> ATP + Creatine BONUS: The enzyme involved is creatine kinase. |
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Term
| Why is creatinine tested for in urine? |
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Definition
| Creatinine, the byproduct of creatine breakdown in the muscles, is processed by the kidneys and excreted in the urine. As its levels are directly related to muscle mass, it is used as a test of kidney function. |
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