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USMLE
New FA Biochem 7
Question | Answer |
---|---|
What are the essential amino acids? | PVT TIM HALL 1. Phenylalanine 2. Valine 3. Threonine 4. Tryptophan 5. Isoleucine 6. Methionine 7. Histidine 8. Alanine 9. Leucine 10. Lysine |
What are the conditionally essential amino acids, and why are they conditionally essential? | The condition is age. They are necessary early in life during growth. Mnemonic: Babies CRY for Help 1. Cysteine 2. aRginine 3. tYrosine 4. Histidine |
Cysteine or Cystine: The amino acid | Cysteine |
Cysteine or Cystine: Two copies of the amino acid joined by a disulfide bond | Cystine |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Phenylalanine | Essential Both glucogenic and ketogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Valine | Essential Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Tryptophan | Essential Both glucogenic and ketogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Threonine | Essential Both glucogenic and ketogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Isoleucine | Essential Both glucogenic and ketogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Methionine | Essential Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Histidine | Essential Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Arginine | Essential Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Leucine | Essential Ketogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Lysine | Essential Ketogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Tyrosine | Conditionally essential (during life and early growth) (Phenylalanine and Tetrahydrobiopterin produce tyrosine and dihydrobiopterin) Both glucogenic and ketogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Glutamate | Inessential (made from alpha-ketoglutarate) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Aspartate | Inessential (made from asparagine or oxaloacetate by aspartate aminotransferase) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Proline | Inessential (Glutamate makes proline and ornithine) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Glycine | Inessential (synthesized during reactions involving tetrahydrofolate) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Cysteine | Conditionally essential (during life and early growth) (Methionine begets S-adenosyl methionine which begets intermediates which beget cysteine) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Alanine | Inessential (made from pyruvate by alanine aminotransferase in the Cori cycle) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Serine | Inessential (made from a descendant of 3PG and with an amine group from glutamate) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Glutamine | Inessential (made from glutamate) Glucogenic |
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Asparagine | Inessential (made from aspartate) Glucogenic |
Which amino acids are acidic? | Aspartate and glutamate are negatively charged at body pH |
Which amino acids are basic? | Arginine, Lysine and Histidine Arginine and Lysine are increased in histones which bind negatively charged DNA. Histidine has no charge at body pH. |
Zinc deficiency: Presentation | "Delayed wound healing, hypogonadism, and decreased adult hair (axillary, facial, pubic)" |
Zinc deficiency: Predisposes to what? | Alcoholic cirrhosis |
Ethanol metabolism: All steps with enzymes and cofactors | "Step 1: Ethanol is oxidized by NAD (forming NADH) to acetaldehyde using alcohol dehydrogenase. Step 2: Acetaldehyde is oxidized by NAD (forming NADH) to acetate using acetaldehyde dehydrogenase." |
Ethanol metabolism: Limiting reagent | NAD+ |
Ethanol metabolism: Order of kinetics of alcohol dehydrogenase | Zero-order kinetics |
Disulfiram: Mechanism | "Disulfiram inhibits acetaldehyde dehydrogenase, leading to an accumulation of acetaldehyde, leading to increased hangover symptoms." |
Which drug inhibits acetaldehyde dehydrogenase? | Disulfiram |
Ethanol hypoglycemia: mechanism | "1. Ethanol metabolism increases NADH/NAD ratio in the liver. 2. Pyruvate and oxaloacetate are reduced by NADH respectively to lactate and malate. 3. Decreased pyruvate and oxaloacetate leads to decreased gluconeogenesis. 4. Decreased gluconeogenesis l |
What are the consequences of the altered NADH/NAD ratio seen in alcoholics? | "Short-term: Hypoglycemia, Long-term: Hepatic fatty change" |
What is the mechanism behind chronic fatty change in alcoholics? | "1. Ethanol metabolism leads to an increased NADH/NAD ratio in the liver. 2. This ratio prefers fatty acid synthesis over glycolysis." |
Kwashiorkor: Clinical picture | Small child with a swollen belly and depigmented hair. |
Kwashiorkor: Clinical presentation | "Kwashiorkor results from protein-deficient MEALS. Malabsorbtion, Edema, Anemia, Liver (fatty change), Skin lesions" |
Protein malnutrition leads to what disease? | Kwashiorkor (as opposed to Marasmus from energy malnutrition) |
Energy malnutrition leads to what disease? | Marasmus (as opposed to Kwashiorkor from protein malnutrition) |
Marasmus: Clinical presentation | "Tissue and muscle wasting, loss of subcutaneous fat, and variable edema" |