Week 5 - Cellular Energy Metabolism Flashcards
What are the 11 products formed in the 10 steps during glycolysis?
Glucose, Glucose-6-phosphate, Fructose-6-phosphate, Fructose-1,6 bisphosphate, Dihydroxyacetone Phosphate, Glyceraldehyde-3-phosphate, 1,3 - bisphosphoglycerate , 3-phosphoglycerate, 2-phosphoglycerate, Phosphophenolpyruvate, Pyruvate
What are the enzymes (in order 0 from steps 1-10 of glycolysis?
- Hexokinase
- Phosphoglucose isomerase
- Phosphofructokinase
- Aldoiase
- Triosephosphate isomerase
- Glyceraldehyde Phosphate dehydrate
- Phosphoglycerate kinase
- Phosphoglycerate mutase
- Enolase
- Pyruvate Kinase
Describe the steps of glycolysis
- Traps glucose in cells, destabilise structure to facilitate later reactions
- Converst 6 carbon ring into 5 carbon ring in prep for triode formation
- Further destabilisation of structure preparation for triode formation
- splits 5 carbon ring into 2x triode sugars
- isomerisation reaction as only g-3-P can proceed fro further reactions
- provide 2x phosphate groups for ATP synthesis in subsequent reactions
- substrate level phosphorylation to produce ATP
- Isomerism to promote formation of more unstable phosphophenol pyruvate
- Formation of unstable product for next reaction
- substrate level phosphorylation of ATP
What are the three key regulatory enzymes in glycolysis and why?
- hexokinase
- Phosphofructokinase
- Pyruvate kinase
These are non reversible enzyme reactions all involving ATP.
Describe the glycerin Phosphate shuffle
- Glycerin-3-phosphate is oxidised to Dihydroxyacetonphosphate - reduction of FAD to FADH2 in mitochondria
- Dihydroxyacetonphosphate transferred to cytosol - undergoes reverse and metabolised to glycerine-3-phosphate requiring NADH oxidised to NAD+ to maintain glycolysis
Describe there malate aspartate shuffle
1.Malate oxidised to oxaloacetate via reduction of NAD+ to NADH
2. oxaloacetate converted to aspartate then back to oxaloacetate to malate and oxidising of NADH to NAD+
This system allows passing of electrons
What is gluconeogenesis?
The formation of glucose from non-carbohydrate sources
- occurs mainly in the liver
What are some gluconeogenec substrates ?
Amino acids (not leucine/lysine) Lactate Pyruvate Gycerol Oxaloacetate
Describe triglycerides in gluconeogeneis
free fatty acid converted to Acetyl CoA
Glycerol converted to glyceraldehyde-3-phosphate and then to fructose 1,6 bisphosphate
Describe Phosphoenol pyruvate formation under normal conditions
- Requirement for ATP + GTP hydrolysis
- pyruvate in mitochondria converted to oxaloacetate via pyruvate carboxylase
- Reduced to malate by mitochondrial malate dehydrogenase and exported to cytosol using NADH
- Cytosolic malate dehydrogenase oxidises malate to oxaloacetate regenerating NADH
- oxaloacetate is converted to PEP via phosphenol pyruvate carboxykinase
Describe phosphenol pyruvate formation in stress conditions/vigorous exercise
- laxctate converted to pyruvate regenerating NADH
- Conversion of pyruvate to PEP in mitochondria
- PEP exported to cytosol
Describe the cori cycle
Where lactate is produced by muscles, transported to the liver where it is converted back to glucose in anaerobic conditions
Describe glycogen formation key processes
- Glucose converted to glucose-1-phosphate
- activation of glucose via additions of UDP to G-1-P
- Addition of UDP, glucose to glycogen molecule via 1,4 alpha link and glycogen synthase
What are the key enzymes in glycogen Glycogen formation
- UDP glucose pyrophosphorylase
- Glycogen synthase
- Glycogen phosphorylase
- Glycogen branching and debranching enzymes
- Phosphoglucomulase
Describe the activation of glucose from glycogen stores
- ATP used in the process to generate UTP from UDP
- Reaction of UTP and glucose-1-phosphate produced UDP glucose and inorganic phosphate
- Catalysed by UDP glucose pyrophosphorylase
- ATP used in the phosphorylation of glucose to glucose 1 phosphate, traps glucose in cell
- Every mole of glucose, 2 moles of ATP consumed
Describe the branching enzyme in glycogenesis
- After 10 glucose have been added to glycogen alpha 1,6 branch point formed via branching enzyme
- Enzyme breaks one alpha 1,4 binds and transfers a block of residues to an interior site in glycogen molecule
- Reattached by 1 alpha 1,6 bond
Branching enzyme = amyloid 1,4 to 1,6 transglycosylase
Describe glycogen Phosphorylase
Breaks alpha 1,4 glycosidic bonds from non reducing end to produce glucose
Describe steps 1 - 4 of the citrate cycle
- oxaloacetate + acetyl CoA to citrate via citrate synthase
- Citrate to isocitrate via Aconitase dehydration and aconite rehydration
- isocitrate to oxalosuccinate to alpha ketogluterate via isocitrate dehydrogenase NAD+ to NADH and decarboxylation
METABOLIC NODAL POINT - alphaketogluterate to succinylCoA via alphaketogluterate dehydrogenase complex NAD+ to NADH, decarboxylation and CoA addition
Describe steps 5-8 of the citrate cycle
- SuccinylCoA to succinate via succinyl CoA synthase
Phosphorylation of GDP to for GTP via succinate, GTP converted to ATP 6. Succinate to fumigate via succinate dehydrogenase FAD+ to FADH2 - Fumerate to malate via carbanion intermediate and Fumerase
- malate to oxaloacetate via malate dehydrogenase and NAD+ to NADH
Describe the essential fatty acids
- stearic acid
- oleic acid - omega 9
- linoleum acid - omega 6
- alpha linoleum acid - omega 3
Describe hormone sensitive lipase
- intracellular
- Inhibition of lipolysis
- provides glycerol-3-phosphate from glycolysis
- promote fat storage
Describe fatty acid synthesis
Acetyl ACP + malonyl ACP
- acyl malonyl ACP condensing enzyme condenses forming ACP and CO2
- Beta ketoacyl ACP reductase reduces to for NADP+
- 3hydroxyacyl ACP dehydrase forming H2O
- Enoyl ACP reductase reduces to form NADP+
- fatty acid chain formed and extended by two carbons , substitute this chain as acetyl ACP and chain increases in length
Describe acetyl CoA availability
Citrate - oxaloacetate - malate - pyruvate - oxaloacetat - citrate with acyl CoA addition
Enzymes = ATPcitrate ligase , malate dehydrogenase, nADp+ liked malate enzyme, Pyruvate carboxylase
Describe fatty acid activation
Mitochondrial process used to transport activated fatty acids across membrane
via carnatine
-Add acetyl CoA to fatty acid to activate
- Use carnatine acyl transferase system replacing CoA with carnatine group
- transported via carnatine acylcarnatine transferase into mitochondrial matrix
remove carnatine group and add CoA
