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151

ATP investing steps of glycolysis?

Hexo/glucokinase. Phosphofructokinase-1.

152

ATP producing steps of glycolysis?

Phosphoglycerate kinase (1,3-BPG -> 3-PG)
Pyruvate kinase (Phosphoenolpyruvate -> pyruvate). Inhibited by ATP, alanine. Pushed by Fructose-1,6-BP.

153

Glycolysis overview?

Glucose, glu-6-p, fructose-6-p,fructose-1,6-bp,G3P+DHAP,->->Phosphoenolpyruvate, pyruvate.

154

Glycolysis and gluconeogenesis are both regulated via this bifunctional enzyme how?

Fructose bisphosphatase-2/pFK-2. fructose-2,5-BP fructose-6-P
Fasting - inc. glucagon, inc cAMP, inc PKA, inc FBPase, inc gluconeogenesis
Fed - inc insulin, dec cAMP, dec PKA, inc PFK-2, inc glyolysis

155

Glycolysis is coupled to TCA how?

Pyruvate dehydrogenase complex: pyruvate + NAD+ + CoA -> acetyl-CoA + CO2 + NADH
5 cofactors: Pyrophosphate (B1), FAD (B2), NAD (B3), CoA (B5), Lipoic acid (inhibited by arsenic)
Inhibited by ATP, Acetyl-CoA, NADH

156

Pyruvate dehydrogenase complex deficiency?

Buildup of pyruvate shunted to lactate (LDH) and alanine (ALT). Tx = Lysine and leucine (ketogenic) to minimize lactic acidosis (shunting metabolism to fat burning)

157

Four ways pyruvate is metabolized

(1) Alanine aminotransferase (B6)
(2) Pyruvate carboxylase (biotin) - makes oxaloacetate for TCA cycle or gluconeogenesis
(3) Pyruvate dehydrogenase (B1-3, 4, liopic acid)
(4) Lactic acid dehydrogenase (B3) - makes lactate. RBCs, leukocytes, kidney medulla, lens, testes, and cornea

158

Krebs cycle overview?

Citrate Is Krebs' Starting Substrate For Making Oxaloacetate
Citrate, Isocitrate, alpha-ketoglutarate, Succinyl-CoA, Succinate, Fumarate, Malate, Oxaloacetate
Produces 3 NADH, 1 FADH2, 2CO2, 1 GTP/CoA = 10 ATP/acetyl-CoA

159

Rate-limiting step of TCA cycle?

Isocitrate dehydrogenase (Isocitrate -> a-KG)
Inhibited by ATP and NADH. Pushed by ADP.

160

Pyruvate carboxylase?

Pyruvate + CO2 -> Oxaloacetate; Used for TCA, gluconeogenesis via malate.
Deficiency - limits TCA cycle. Lactic acidosis. Mental retardation < age 5.

161

What is the gradient in oxidative phosphorylation?

H+ produced in inter membrane space. NADH, FADH2, H20, and ATP are in the matrix.
1 NADH -> 2.5 ATP; 1 FADH2 -> 1.5 ATP

162

Oxidative phosphorylation poisons?

E- transport inhibitors: rotenone (I), antimycin A (III), cyanide & CO (IV)
ATP synthase inhibitors: oligomycin
Uncoupling agent: ATP synthesis stops but electron transport continues. (2,4-dinitrophenol, ASA, thermogenin in brown fat)

163

Gluconeogenesis overview?

Pathway Produces Fresh Glucose. Starts after fasting 12-18h.
1. Pyruvate carboxylase (Pyruvate -> oxaloacetate; biotin, ATP); mitochondria
2. Phosphoenolpyruvate carboxykinase (Oxaloacetate -> phosphoenolpyruvate)
3. Fructose-1,6-bisphosphatase (Fructose-1,6-BP--> Fructose-6P); Inhibited by F 2,6P. Pushed by citrate.
4. Glucose-6-phosphatase (Glycose-6P->Glucose). ER
Primarily in liver, also kidney. Odd-chain FA's can enter TCA via succinyl-CoA to become glucose but even-chains destined for acetyl-CoA.

164

Key enzymes in HMP shunt?

Glucose-6-P dehydrogenase (glucose-6P -> ribulose 5-P)
Phosphopentose isomerase, transketolases (Ribulose 5-P -> ribose-5-P, G3P, F6P). Req. b1.

165

What is the respiratory/oxidative burst?

Phagocytic NADPH oxidase complex that rapidly releases ROS to kill bacteria. Most important enzyme = NADPH oxidase (whose deficiency = chronic granulomatous disease). O2->O2-->H2O2+Cl- -(Myeloperoxidase)-> bleach
Other enzymes degrade H2O2 and require SELENIUM to do so.

166

What type of organisms are patients with chronic granulomatous disease susceptible to?

Catalase + specieies (e.g. Staphs, Aspergillus). B/c these organisms catalase their own H2O2 leaving phagocytes w/o any substrate for oxidative burst.

167

Leber's hereditary optic neuropathy

Mitochondrial (maternal transmission) mutation of complex I often leads to optic nerve death 2/2 ischemia by early adulthood.

168

Arsenic poisoning symptoms

Cholera-like symptoms. tx - chelation; Arsenic inhibits lipoid acid requiring enzymes like PDH complex, aKG DH, transketolase

169

Conversion of NE to Epi occurs where and how?

Adrenal medulla. Phenylethanolamine-N-methyltransferase (PNMT). Controled by cortisol (increases transcription).

170

Synthesis of serotonin?

Tryptophan req. BH4 -(tryptophan hydroxylase)-> 5-hydroxytryptamine -> serotonin

171

Elastin synthesis?

Tropoelastin precursors (Gly, ala, val w/ non-hydroxylated pro and lys). After secretion, binds with fibrillin. Lysine residues bound covalently as desmosine cross-link = elastic properties. NO triple helix.

172

What protein regulates G1->S transition?

Rb. Active=hypophosphorylated, which binds to E2F. Hyperphosphorylated Rb (via CDK4) -> E2F transcription factor release.

173

Niemann-Pick disease

Spingomyelinase. Spinhingomyelin. AR. Ashkenazi, 1st yr with hepatosplenomegaly, hypotonia, ID. "FOAMY histiocytes" in liver and spleen and neuro. CHERRY-red macular spot (Tay-sachs like). Death by 3.

174

What monosaccharide is most rapidly metabolized?

Fructose. B/c F-1-P bypasses PFK-1 by being converted by Aldolase B (Hereditary fructose intolerance) into DHAP and Glyderaldehyde.

175

P50 of Hgb v. P50 of Mgb?

25 mmHg v. 1 mmHg; 1 Quarter for the hemoglobetrotters.

176

Galactose metabolism?

Most commonly from lactose (glucose-galactose), with lactase in GI breaking down. Galactose -(galactokinase)-> galactose-1P -(Uridyltransferase)-> Glucose-1-P

177

Galactokinase deficiency?

AR. Galactose in blood and urine. Galactitol accumulation (via aldose reductase) -> infantile cataracts (failure to track or develop social smile).

178

Classic galactosemia

AR. Absence of galactose-1-phosphate uridyltransferase. Galactitol accumulation (via aldose reductase) -> cataracts. FTT, jaundice, hepatomegaly, ID. Tx = exclude galactose and lactose. e. coli sepsis.

179

Sorbitol

Keeping glucose in a cell for later use into fructose via sorbitol dehydrogenase. (Glucose -aldose reductase-> sorbitol). Liver, ovaries, seminal vesicles have both. Schwann cells, retina, kidneys, lens primarily has aldose reductase, making these cells susceptible to osmotic dmg with hyperglycemia OR with high galactose lvls.

180

Lactase deficiency

Primary - age-dependent decline (absence of lactase-persistent allele). Secondary - loss of BRUSH BORDER. Dx - stool w/ dec. pH and breath with inc. hydrogen content with lactose tolerance test, or inc. stool osmotic gap.