Flashcards in Biochemistry Deck (255)
Carnitine shuttle is required to move LCFA's into mitochondria to be broken down. W/o carnitine, accumulated LCFA's --> cardiomyopathy, myopathy, encephelopathy, fasting hypoglycemia (carnitine palmitoyltransferases I or II)
Only occurs in mitochondria of liver cells with lots of acetyl-CoA present. Acetoacetate and 3-hydroxybutyrate can be used peripherally. Acetone, cannot, and leaves via lungs (fruity odor)
Kcal per protein, carb, fat?
4,4,9. (Area code in Mexico; 449. And 9 is fat).
How much time does it take to deplete glycogen?
Starvation days 1-3:
Hepatic glycogenolysis, adipose release of FFA, muscle and liver use FFA, hepatic gluconeogenesis
Adipose stores mostly. Ketone bodies dominate brain energy source. Afterwards, vital protein degradation accelerates.
Main purpose of Chlyomicrons, VLDL, LDL, HDLs
Chylos take dietary lipid to tissues. VLDL's deliver hepatic TG's to peripherals. LDL delivers hepatic cholesterol to peripheral tissues (receptor-mediated endocytosis). HDL takes excess tissue cholesterol back to liver.
What enzyme removes supercoils?
Fetal hemoglobin is made up of what subunits?
a2b2 = HbA1; a2d2 = HbA2; a2g2 = HbF
How does NE get to Epi?
NE + SAM -Phenylethanolamine-N-methyltransferase(PNMT)-> Epi + S-adenosylhomocysteine
The Five Great cofactors are needed for what 3 enzymes?
Pyruvate dehydrogenase, alpha-ketoacid dehydrogenase (Maple), alpha-ketoglutarate dehydrogenase (TCA). Thiamine, lipoic acid, CoA, FAD, NAD+
What part of ribosome binds to Shine-Dalgarno sequence of mRNA?
16S rRNA of 30S ribosomal subunit (prokaryotic); You Shine when you're 16.
Where do all the electron acceptors come from in the Krebs?
NADH produced by isocitrate dehydrogenase, a-KG dehydrogenase, and malate dehydrogenase. FADH2 produced by succinate dehydrogenase. GTP produced by succinyl CoA synthetase.
Affinity for sulfhydryl groups leading to inhibition ALA-dehydrase and Ferrochetolase -> dec. heme synthesis. Microcytic anemia (2/2 inhibited delta-ALA dehydrates and reduced Fe into heme), Basophilic stippling (abl aggregation of ribosomes), colicky abdominal pain, constipation, BLUISH pigment at gum tooth, wrist drop/foot drop. 10ug/dL Tx = EDTA or dimercaprol
Rapidly cutaneous flushing, tachypnea, HA, tachycardia, n/v, confusion. Severe lactic acidosis. Mech - binds cytochrome a-a3, stopping oxidative phosphorylation. Tx = nitrites. Induce formation of methemoglobin, which sequesters cyanide. Sodium thiosulfate can also bind.
Heme synthesis overview
Fe2+ and protoporphyrin IX -(ferrochelatase)-> Heme...requires mitochondria. Rate-limiting step is Gly + Succinyl CoA -(ALA synthase)-> aminolevulinic acid. ALA synthase is activated by alcohol, barbiturates, and hypoxia. Mostly synthesized in hepatocytes and erythrocytes, which lose their ability when they lose their mit. Lead affects ferrochelatase and ALA DEhydratase.
Photosensitivity is key feature. Pink-tinted urine that darkens 2/2 porphobilinogen secretion (intermediate). Chronic porphyria due to def. of uroporphyrin decarboxylase. Acute porphyria often due to liver (excessive expression of ALA synthase.
SEVEN transmembrane regions. Alpha-GDP -> Alpha-GTP---> alpha dissociates w/ beta+gamma -> activates adenylate cyclase or phospholipase C. Phospholipase C - produce IP3 and DAG. DAG -> PKC. IP3 -> inc. intracellular Ca -> elevated PKC.
Harnup disease -
Niacin deficiency b/c of loss of dietary tryptophan b/c of defective intestinal and renal tubular absorption. B3 is made from typtophan.
Reg gene, promoter gene, operator gene, 3 structural genes called z, y a. Beta-galactosidase, permease, repressor protein. Lactose binds to repressor protein --> PREVENT attachment of repressor to operator. Glucose --> decreased cAMP -> decreased expression (b/c high cAMP activates CAP to bind to promoter)
Involved with catabolism of Ile, Val, Met, Threonine ("Ill Val Met Three") cholesterol and odd-chain FA's. Converted to methylmalonyl CoA (propionyl CoA carboxylase, biotin, carboxylation), which is then converted to Succinyl CoA (methylmalonyl CoA isomerase, B12, isomerization)
Potent toxin from castor oil plant that inhibits protein synthesis by cleaving rRNA component of euk. 60S
Ketones are metabolized by what tissues?
Brain, skeletal muscle, cardiac muscle, renal cortex. Cells w/o mitochondria can't use ketone bodies. Liver cannot either b/c they lack succinyl CoA-acetoacetate coA transferase
When a pair of alleles from two loci are inherited together more or less often than would be expected by random chance alone. Not necessarily physical proximity.
Role of liver in triglyceride metabolism?
TG's are stored in adipose, metabolized to FA's + glycerol by hormone sensitive lipase. The glycerol is transported to liver where phosphorylated by glycerol kinase. Then converted to DHAP -> glycolysis or gluconeogenesis.
Mutations in different genes leading to similar phenotypes
Same genotype, different phenotypic expression. (NOT penetrance)
Marfan vs. Ehlers-Danlos syndrome
EDS - hypermobile joints, hyper elastic skin, fragile tissue susceptible to bruising. Marfan - lens dislocation, aortic aneurysms, long and tall, also hypermobile joints