L6-10- Metabolism overview Flashcards
how many stages of catabolism of carbohydrates
4
stage 1
breakdown of carbohydrates into glucose
stage 2
glycolysis
stage 3
Kreb cycle/TCA
stage 4
Electron transport stage
outline stage 1
Extracellular process
- breakdown of carbohydrates into glucose
- glucose absorbed in the gut
outline stage 2
cytosolic and mitochondrial
- 1 glucose (C6) –> 2Pyruvtae, 2NADH and 2ATP
outline stage 3
mitochondrial
- pyruvate loses a CO2 and is converted to Acetyl CoA
- acetyl CoA enters the kerb cycle
- produces NADH, GTP and FADH
GTP
ATP equivalent in Krebs cycle
outline stage 4
- mitochondrial membrane
- NADH and FADH from Kreb feeds into the ETC
- Proton motive force is used to power the ATP synthase which synthesises ATP from ADP and Pi
stages 1 to 3 are
substrate level phosphorylation
stage 4 is
oxidative phosphorylation
which stage produces the most TP
ETC
during stage 1 proteins are broken down into
amino acids
during stage 1 CHOs are broken down into
monosaccharides
name 3 monosaccharides
galactose
glucose
fructose
during stage 1 lipids are broken down into
glycerol and fatty acids
all of catabolism of CHOs is
oxidation
what makes a step irreversible
when it loses carbon dioxide
glycolysis is a ….. process which produces…. ATP
exergonic… 2 ATP
name 3 enzymes which control glycolysis
1) hexokinase
2) phosphofructokinase
3) pyruvate kinase
glycolysis is ….. activated
hormonally
- PFK
- pyruvate kinase
where does hexokinase work
between glucose and glucose-6-phosphatw
hexokinase is an example of
a negative regulator
phosphofructokinase (PFK) is regulated differently by
the liver and the muscles
How is PFK regulated in the muscle
allosteric regulation
PFK in muscle stimulated by
AMP
PFK in muscle inhibited by
ATP
PFK in liver stimulated by
insulin
PFK in liver inhibited by
glucagon
phosphofructosekinase converts what to what
Fructose 6 phosphate to fructose 1,6- bisphopshate
pyruvate kinase converts
phosphoenolpyruvate –> pyruvate
Pyruvate kinase is inhibited by
phosphorylation- e.g protein kinase A (glucagon)
pyruvate is stimulated byq
phosphatase (insulin)
stage 3- Krebs cycle takes place in
mitochondrial matrix
Krebs cycle known as
hub of metabolsim
each pruvate goes round ….. to produce the products of the kreb cycle
2 cycles
Krebs cycle is the central metabolism pathway for
- sugar
- fatty acids
- ketone bodies
- amino acids
- alchohol
what stimulates the kreb cycle
AMP and NAD+ (low energy signals)
what inhibits the kreb cycle
ATP and NADH (high energy signals)
products of the Kreb cycle
6 NADH
2 FAD2H
2 GTP
2 CO2 (from Acetyl- CoA)
products form the kerb cycle are
precursors for biosynthesis
stage 4- the electron transport chain requires
oxygen
the ETC is where
most of the ATP is produced
where does stage 4 take place
Cristae of the mitochondria
outline stage 4
1) electrons from NADH and FADH (from glycolysis and Krebs) are given up to the PTC1
2) electrons from from PTC1 to PTC2 to PTC 3, this releases energy which pumps H+ ions across the membrane
3) At PTC3, oxygen combines with electrons and @H+ ions –> water released
4) high conc of H+ ions in the inner membrane compared to the inside of the mitochondria–> proton motive force
5) H+ ions diffuse through the ATP synthase down the conc. gradient
energy released during electron transport
30% pumps H+ across the inner membrane
70% released as heat
ATP synthase
ADP –> ATP
- Protons can only return across the membrane via ATP synthase
what can affect ATP synthase production of ATP
uncoupling reactions
PTC stands for
proton translocating compelx
stage 1 of lipid metbolism
1) TAG broken down to glycerol and fatty acids.
2) fatty acids converted by to TAGa nd stored in adipose
3) Fatty acids released into blood during low blood glucose
4) fatty acid metabolism starts
5) fatty acids activated –> fatty acyl coA
6) carnitine shuffle
7) B oxidation of fatty acyl CoA to acetyl CoA
8) Acetyl CoA enters the kreb cycle and ATP synthase
stage 1 of lipid metabolism
- Triglycerides (TAG) eaten and converted to glycerol and fatty acids in the gut
- fatty acids converted back to TAG and absented
- TAG is then transported in the blood to adipose tissue via chylomicrons
- TAG stored in adipose tissue
- released as fatty acids when glucose is low and carried to consumer tissue as albumin-fatty acid complex
what transports TAG to adipose tissue from the blood
chylomicrons
when are fatty acids released from adipose tissue
when blood glucose is low
how are fatty acids carried to consumer tissue
via the albumin-fatty acid complex
stage 2 of lipid metabolism
- fatty acid activation –> Acyl CoA
- fatty acyl-Co-A binds to carnitine to produce Acyl carnitine (loses CoA)
- acyl carnitine is then transported across the mitochondrial membrane via the carnitine shuffle transporter
- once within the mitochondria the acyl carnitine lose carnitine loses and recombines with CoA to from Acyl CoA
how are fatty acids activated by
combine with Coenzyme A by fatty acyl coA synthase to produce AcylCoA
B-oxidation of lipids
when fatty acids chain gets oxidised within B-oxidation cycle
every cycle of B-oxidation how many carbons are lost
2 carbons
what is released during B-oxidation
FADH and NADH and acetyl coA (2C)
FADH and NADH from B-oxidation
used to produce the proton motive force which powers ATP synthase
