Part 2 Flashcards
How much of the body’s energy needs can be met by amino acid oxidation in the TCA cycle?
10-15% of the body’s energy needs.
When do amino acids become a primary source of energy?
During starvation, prolonged fasting, or in conditions like diabetes mellitus when carbohydrates are unavailable or cannot be used properly.
What is gluconeogenesis?
The process of glucose formation from non-carbohydrate sources.
Which organs primarily perform gluconeogenesis?
Liver and kidneys.
Which tissues rely on glucose produced from amino acids during starvation?
Brain, red blood cells (RBCs), and other tissues.
What distinguishes glucogenic from ketogenic amino acids?
Glucogenic amino acids degrade into pyruvate or TCA cycle intermediates; ketogenic amino acids degrade into Acetyl CoA or Acetoacetyl CoA.
Name four specialized products synthesized from amino acids.
- Porphyrins
- Neurotransmitters
- Hormones
- Purines/pyrimidines
What two molecules combine with glycine to form heme?
Succinyl CoA and glycine.
Which amino acids are required for creatine synthesis?
- Glycine
- Arginine
- Methionine
What role does glycine play in detoxification?
It conjugates with benzoic acid to form hippuric acid for detoxification.
What is the main function of creatine phosphate?
To maintain intracellular ATP levels during intense muscular contraction.
How is creatinine used in medical diagnostics?
Its levels in serum (along with blood urea) are used as a diagnostic test for kidney function.
Which sulfur-containing amino acids are discussed?
- Methionine
- Cysteine
- Cystine
What is the function of S-Adenosylmethionine (SAM)?
SAM donates methyl groups to various acceptors and is involved in the synthesis of polyamines like spermine and spermidine.
What conditions are associated with high homocysteine levels?
- Atherosclerosis
- Osteoporosis
- Alzheimer’s disease
- Parkinson’s disease
- Stroke
- Cardiovascular diseases
Which vitamins help reduce homocysteine levels?
- Folate
- Vitamin B6
- Vitamin B12
What enzyme deficiency causes homocystinuria?
A deficiency of cystathionine synthase.
Name three branched-chain amino acids.
- Valine
- Leucine
- Isoleucine
What is the primary metabolic disorder associated with branched-chain amino acids?
Maple Syrup Urine Disease (MSUD).
What enzyme deficiency causes MSUD?
A deficiency of α-Keto acid dehydrogenase.
What symptoms are associated with MSUD?
- Acidosis
- Lethargy
- Convulsions
- Mental retardation
- Coma
- Potentially death within the first year of life
How can mild cases of MSUD be treated?
Mild cases respond to high doses of thiamine; severe cases may require liver transplantation.
Which amino acid is cleaved by arginase to produce urea and ornithine?
Arginine.
What condition results from defective arginase?
Hyperargininemia, an inborn error of arginine metabolism.
Which enzyme catalyzes the formation of nitric oxide (NO) from arginine?
Nitric oxide synthase (NOS).
Name two therapeutic uses of nitric oxide (NO).
- Treatment of angina pectoris
- Treatment of pulmonary hypertension
What condition can result from a deficiency of folic acid in histidine metabolism?
Accumulation of FIGLU in urine.
What inhibitory neurotransmitter is derived from glutamate?
γ-Amino butyrate (GABA).
Which vitamin deficiency can lead to reduced GABA levels and convulsions?
Vitamin B6 deficiency.
What is the function of the Alanine-Pyruvate shuttle?
To transport pyruvate as alanine from muscles to the liver for gluconeogenesis.
