Biochemistry (Gen Principles) Flashcards
blue sclera seen in osteogenesis imperfecta (collagen defective disorder) BITE
B = bones - multiple fractures
I(eye) = blue sclera
T = teeth imperfections
E = ear - hearing loss
1st step in Glycolysis
splitting and breakdown of glucose occurs in cytoplasm
glucose to G-6-P by a kinase (hexokinase/glucokinase - liver - inhibited by F6P) that uses ATP (irreversible) - commits glucose
PFK-1 in glycolysis
converts F6P to F1,6BP
PFK-1 is a rate limiting step of glycolysis (slowest reaction in the pathway) - the true commitment step for glycolysis
stimulated by amp to work fastest (we are low in energy - work faster) also stimulated by F2,6BP
Vitamin A toxicity
signs of Vitamin A toxicity include benign intracranial HTN (ex: HA, vomiting, papilledema), dry skin and hepatomegaly; risk factors include excessive dietary intake (ex: egg, liver and kidney) or retinoid-containing medications
Gluconeogenesis
Acetyl-CoA stimulates gluconeogenesis by increasing the activity of pyruvate carboxylase when acetyl-CoA is abundant; this regulatory step allows pyruvate to be shunted toward acetyl-CoA production when acetyl-CoA levels are low, preventing the cell from becoming depleted of energy
organic acidemia
propionyl-CoA is derived from the metabolism of valine, isoleucine. methionine, threonine, and odd-chain FAs; congenital deficiency of propionyl-CoA carboxylase, the enzyme responsible for the conversation of propionyl-CoA to methylmalonyl-CoA leads to the development of propionic academia; the condition presents w lethargy, poor feeding, vomiting and hypotonia 1-2 weeks after birth
primase
primase is a DNA-dependent RNA polymerase that incorporates short RNA primers into replicating DNA
thiamine-dependent enzymes in the TCA cycle
pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase require thiamine as a cofactor
small nuclear ribonucleoproteins (snRNPs)
small nuclear ribonucleoproteins (snRNPs) are important components of the spliceosome, a molecule which improves introns from pre-mRNA during processing within the nucleus; spinal muscular atrophy is a disorder caused by mut in SMN1 gene resulting in impaired assembly of snRNPs in LMNs; infants often have flaccid paralysis due to degeneration of anterior horn cells in the spinal cord
radiation injury
exposure to ionizing radiation, including therapeutic and palliative radiation therapy, induces DNA damage through DNA double-strand fractures and the formation of oxygen free radicals
RNA interference in translation
short non-coding RNA sequences induce post transcriptional gene silencing by base-pairing w complementary sequences within target mRNA molecules
PTH Calcium-sensing receptors (CaSRs)
Calcium-sensing receptors (CaSRs) are G-protein receptor that regulate the secretion of PTH in response to changes in circulating Ca2+ levels
Vitamin A deficiency
Fructose metabolism
essential fructosuria is a benign disorder of fructose metabolism caused by fructokinase deficiency; in pts w essential fructosuria, some of the dietary fructose load is converted by hexokinase to fructose-6-phosphate which can then enter glycolysis; this pathway is not significant in normal individuals
Collagen
glycine is the most abundant amino acid in collagen; the triple helical conformation of collagen molecules occurs due to the repetitive amino acid sequence within each alpha chain in which glycine occupies every 3rd amino acid position (Gly-X-Y)
fates of pyruvate
impaired intestinal blood flow creates an anaerobic environment that leads to an elevated NADH/NAD+ ratio; this decreases activity of PDH while stimulating lactate dehydrogenase shunting the metabolic fate of pyruvate towards lactate production; pts w significant tissue ischemia are therefore at risk for lactic acidosis
GTP in the TCA
