Metabolism — Flashcards

Flashcard 1041: Where in the cell does conversion of oxaloacetate -> PEP take place?_____

Answer: Cytosol

Flashcard 1042: What mitochondrial enzyme reduces superoxide (O2-) to H2O2? _____

Answer: Superoxide dismutase

Flashcard 1043: O2- is converted to _____ by the enzyme superoxide dismutase (oxidative burst)

Answer: H2O2

Flashcard 1044: Unconjugated bilirubin travels in the blood bound to _____

Answer: albumin

Flashcard 1045: The Ubiquitin-Proteasome system is recruited in response to _____ proteins as a result of cellular stress

Answer: damaged

Flashcard 1046: Vitamin B9 (folate) deficiency is characterized by _____ methylmalonic acid levels

Answer: normal

Flashcard 1047: _____ disease presents with vomiting, poor feeding, and urine that smells like maple syrup/burnt sugar

Answer: Maple syrup urine

Flashcard 1048: When insulin binds its receptor, the receptor _____ and is activated via tyrosine kinase activity

Answer: autophosphorylates (or undergoes autophosphorylation)

Extra: The insulin receptor (and IGF-1 receptor) is unique among receptor tyrosine kinases because it exists as a **pre-formed tetramer** ($\alpha_2\beta_2$ structure) linked by disulfide bonds. Unlike other RTKs (e.g., EGF, PDGF receptors) which must **dimerize** upon ligand binding, the insulin receptor simply undergoes a conformational change that triggers **autophosphorylation** of its internal tyrosine kinase domains.

Flashcard 1049: Atrophy via decrease in cell size may occur via _____ degradation of cytoskeleton

Answer: ubiquitin-proteasome

Flashcard 1050: Pompe disease is associated with exercise _____

Answer: intolerance