difference between catabolic and anabolic pathways
anabolic- combines small molecules to form complex molecules using energy
catabolic- degrades complex molecules into simple products, captures chemical energy in the form of ATP, allows molecules to be converted to building blocks
what is aerobic glycolysis
occurs in cells with mitochondria and oxygen
what happens in anaerobic glycolysis
pyruvate reduced to lactate, allows production of ATP in tissues that lack mitochondria
what is glycolysis and its purpose
splitting of sugar, provides energy and intermediates for other pathways
uses of glucose
storage (glycogen, starch, sucrose), synthesis of structural polymers (extracellular matrix, cell wall polysaccharides), ribose 5-phosphate from oxidation via pentose phosphate path, pyruvate from oxidation via glycolysis (oxidation from energy generation)
2 phases of glycolysis
energy investment and energy generation
invests 2 ATP, then 2 NADH and 4 ATP, net gain of 2 ATP
name and describe the 10 steps of glycolysis (glucose to pyruvate)
- hexokinase catalyses transfer of phosphate from ATP to position carbon6 in glucose to make glucose-6-phosphate
- glucose-6-phosphate converts into fructose-6-phosphate (both are hexose with 6 carbons but furanose replaces pyranose)
- phosphate transfers from ATP to carbon 1 to make fructose-1,6-bisphosphate
- splits into 2 molecules with aldolase so now have 2 3-carbon molecules (convertible/reversible)
- interconverts the 3c substrates, glyceraldehyde-3-phosphate enters second phase (2 molecules so step 6-10 happens twice for 1 glucose)
- inorganic phosphate (not from ATP) added to reduce NAD to NADH, product formed is 1,3-bisphosphoglycerate
- 1,3-bisphosphoglycerate donates a phosphate to ADP, catalysed by phosphoglycerate kinase to make 3-phosphoglycerate (substrate level phosphorylation)
- phosphate moves position, catalysed by phosphoglycerate mutase to make 2-phosphoglycerate
- water is removed, catalysed by enolase to make phosphoenolpyruvate, shift of phosphate from carbon3 to 2, reversible, redistribution of energy within substrate
- phosphate group removed and added to ADP, catalysed by pyruvate kinase to make pyruvate
what does the phosphorylation of glucose ensure/why is it necessary
ensures the glucose stays inside cell as it is an uncharged molecule and doesnt leave by diffusion, exergonic, release of energy prevents reversal
what is a kinase
enzyme which catalyses the transfer of a phosphoryl group from ATP to an acceptor molecule (adds phosphate group from ATP)
what kinase is part of the glycolytic pathway
carbohydrate kinase
difference between kinase, phosphorylase and phosphatases
kinase- adds phosphate group from ATP
phosphorylases- add inorganic phosphate
phosphatases- removes a phosphate from a phosphorylated substrate
is step 1 exergonic or endergonic
exergonic
is step 2 exergonic or endergonic
endergonic
is step 3 exergonic or endergonic and why
exergonic, energy released to prevent reverse, one direction
is step 4 exergonic or endergonic
endergonic
is step 5 exergonic or endergonic
endergonic, converts keto group to aldehyde group
what is the warburg effect and its diagnostic and therapeutic benefits
normal cells gain energy form oxidative phosphorylation and cancer cells produce energy from glycolysis
diagnostic benefits- radioactive glucose accumulates in malignant cells and can be imaged by PET scans, can selectively enrich/label glucose as cancer cells use more of it for imaging
therapeutic benefits- substances can be tested for cancer treatment, toxic glucose like compounds can target cancer cells
what is glycolysis
breaking down glucose to produce energy
