5 Metabolism

Question 1

Oxidative phosphorylation

Answer 1

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.

Question 2

Glukogenes

Answer 2

Bildandet av lagringsformen glykogen från glukos.

Kräver energi.

Question 3

Glykogenolys

Answer 3

Glykogen nedbrytning till glukos.

Question 4

Pentosfosfathunten

Answer 4

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.

Question 5

Biological oxidation

Answer 5

1) Pyruvate dehydrogenase
2) TCA/ Citric acid cycle
3) Electron transport chain
4) Oxidative phosphorylation

Question 6

Regulation of PDH and TCA

Answer 6

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

Question 7

Catabolism of AAs

Answer 7

1 Transaminate

2 Deaminate glutamate: remove N -> ammonia

3 Urea cycle: make urea from the ammonia -> excrete

Question 8

Fate of the carbon skeleton

Answer 8

A) Glucogenic AAs: can give glucose

B) Ketogenic AAs: can give ketones & FAs: Leu, Lys

C) Glucogenic & ketogenic AAs: can give both (4 AAs)

Question 9

Fate of nitrogen

Answer 9

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

Question 10

Glykolysen

Answer 10

Glukos till energi

Question 11

Netto från 1 glukos molekyl

Answer 11

2 NADH
2 ATP
2 Pyruvat

Question 12

Netto (anaeroba förhållanden)

Answer 12

2 ATP
2 Laktat
2 NADH oxideras till 2 NAD+ (kan köra mer glykolys)

Question 13

Glykolysens tre reglerande steg

Answer 13

Steg 1: Hexokinas

Steg 3: Fosfofruktokinas

Steg 10: Pyruvatkinas

Question 14

Glukoneogenes

Answer 14

Glukos syntetiseras av laktat, glycerol, aminosyror.

Question 15

Coricykeln

Answer 15

Lever: glukoneogenes (laktat -> glukos) via blodet till muskler

Muskel: glykolys (glukos -> laktat) via blodet till levern

Question 16

Lipidomsättning

Answer 16

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)

Question 17

Ketonkroppar

Answer 17

Sker i leverns mitokondrier under svält.

Ketoner from överbliven Acetyl-CoA förser hjärnan och övriga vävnader = sparar på glukos och protein.

Question 18

Anabolism of FAs & triacylglycerols

Answer 18

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

Question 19

Types of regulation

Answer 19

Allosteric regulation

Covalent modification

Regulation of gene expression

Question 20

Insulin

Answer 20

Released from: pancreatic β- cells 
Upon: high [glucose] 
Stimulates: decrease [glucose] 
By increasing: uptake & storage 
Target: most cells; especially liver, adipose & muscle

Question 21

Glucagon

Answer 21

Released from: pancreatic β- cells 
Upon: low [glucose] 
Stimulates: increase [glucose] 
By increasing: release from storage 
Target: mainly liver, no receptors in muscle

Question 22

Adrenalin

Answer 22

Released from: adrenal gland  
Upon: stress, exercise, low [glucose] 
Stimulates: increase [glucose] 
By increasing: release from storage 
Target: most cells; liver, adipose & muscle

Question 23

Cortisol

Answer 23

Released from: adrenal cortex 
Upon: prolonged stress/ starvation
Stimulates: gluconeogenesis/ lipolysis 
By increasing: release from storage 
Target: most cells; liver, adipose & muscle

Question 24

The process how insulin increases glucose uptake by muscle & adipose cells

Answer 24

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

Question 25

De novo syntes

Answer 25

1 Aktivering av ribos-5-fosfat till fosforibosylpyrofosfat (PRPP)

2 Kvävebas (Purin/pyrimidin) på 1´ kolet istället för pyrofosfat.

Question 26

Nukleotidnedbrytning

Answer 26

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

Question 27

Salvage syntes

Answer 27

Återanvändning av nukleotider, nukleosider och baser

• Nukleosid —> Nukleotid (fosforylering)
• Färdigs kvävebaser ex. A/G kan kopplas på PRPP av speciella salvage-enzym.