5 Metabolism Flashcards
Oxidative phosphorylation
Stage 1: Energy of electron transport is used to pump protons across membrane.
Stage 2: Energy in the proton gradient is harnessed by ATP synthase to make ATP.
Glukogenes
Bildandet av lagringsformen glykogen från glukos.
Kräver energi.
Glykogenolys
Glykogen nedbrytning till glukos.
Pentosfosfathunten
Substrat: Glukos -6- fosfat.
Produkt:
•NADPH; Ges av irreversibla reaktioner. Behövs för anabola reaktioner i cellen.
•och Ribos-5- fosfat; Ges av reversibla reaktioner. Behövs till nukleotidsyntes.
Biological oxidation
1) Pyruvate dehydrogenase
2) TCA/ Citric acid cycle
3) Electron transport chain
4) Oxidative phosphorylation
Regulation of PDH and TCA
a) Energy state of the cell; High energy state: PDH & TCA slow down. Low energy state: PDH & TCA speed up.
b) Allosteric regulation by TCA intermediates
c) Ca2+ stimulate
Catabolism of AAs
1 Transaminate
2 Deaminate glutamate: remove N -> ammonia
3 Urea cycle: make urea from the ammonia -> excrete
Fate of the carbon skeleton
A) Glucogenic AAs: can give glucose
B) Ketogenic AAs: can give ketones & FAs: Leu, Lys
C) Glucogenic & ketogenic AAs: can give both (4 AAs)
Fate of nitrogen
1 Transamination gives glutamate
2 Deamination of glutamate = NH4+
3 Production of urea in the urea cycle;
•NH4+ bound as carbamoyl phosphate in the mitochondria
•NH3 = group from aspartate
Glykolysen
Glukos till energi
Netto från 1 glukos molekyl
2 NADH
2 ATP
2 Pyruvat
Netto (anaeroba förhållanden)
2 ATP
2 Laktat
2 NADH oxideras till 2 NAD+ (kan köra mer glykolys)
Glykolysens tre reglerande steg
Steg 1: Hexokinas
Steg 3: Fosfofruktokinas
Steg 10: Pyruvatkinas
Glukoneogenes
Glukos syntetiseras av laktat, glycerol, aminosyror.
Coricykeln
Lever: glukoneogenes (laktat -> glukos) via blodet till muskler
Muskel: glykolys (glukos -> laktat) via blodet till levern
Lipidomsättning
1) Release of FAs from TAGs in adipose
2) Activation of FAs to acetyl - CoA
3) Transport across mitochondrial IM; the carnitine shuttle
4) Beta - oxidation of FAs in the matrix (gives 9 acetyl- CoA to TCA + 8 NADH/FADH2)
Ketonkroppar
Sker i leverns mitokondrier under svält.
Ketoner from överbliven Acetyl-CoA förser hjärnan och övriga vävnader = sparar på glukos och protein.
Anabolism of FAs & triacylglycerols
1) Transport of acetyl- CoA to cytosol
2) The synthesis of malonyl - CoA
3) Build up of a FA hydrocarbon chain: FA synthesis
4) Storage of FAs as triacylglycerols
Types of regulation
Allosteric regulation
Covalent modification
Regulation of gene expression
Insulin
Released from: pancreatic β- cells Upon: high [glucose] Stimulates: decrease [glucose] By increasing: uptake & storage Target: most cells; especially liver, adipose & muscle
Glucagon
Released from: pancreatic β- cells Upon: low [glucose] Stimulates: increase [glucose] By increasing: release from storage Target: mainly liver, no receptors in muscle
Adrenalin
Released from: adrenal gland Upon: stress, exercise, low [glucose] Stimulates: increase [glucose] By increasing: release from storage Target: most cells; liver, adipose & muscle
Cortisol
Released from: adrenal cortex Upon: prolonged stress/ starvation Stimulates: gluconeogenesis/ lipolysis By increasing: release from storage Target: most cells; liver, adipose & muscle
The process how insulin increases glucose uptake by muscle & adipose cells
1 Insulin binds to insulin receptor
2 Intracellular signalling cascade
3 More glucose transporters (GLUT-4) to cell membrane.
4 Increased uptake of glucose through GLUT-4
De novo syntes
1 Aktivering av ribos-5-fosfat till fosforibosylpyrofosfat (PRPP)
2 Kvävebas (Purin/pyrimidin) på 1´ kolet istället för pyrofosfat.
Nukleotidnedbrytning
1 Fosfataser och nukleotidaser tar bort fosfatgrupper —> nukleosider (P-P-P => OH)
2 Kvävebaser tas loss från nukleosid m.h.a fosforylys (Kvävebas => P)
3a Pyrimidiner: ring öppnas och bryts ned till lösliga ämnen.
3b Puriner: ring kvar men görs mer löslig i form av urinsyra
Salvage syntes
Återanvändning av nukleotider, nukleosider och baser
- Nukleosid —> Nukleotid (fosforylering)
- Färdigs kvävebaser ex. A/G kan kopplas på PRPP av speciella salvage-enzym.
