module 5 - 18.3 the krebs cycle Flashcards
what happens during the krebs cycle? (stage 1-5)
- link reaction delivers acetyl groups into Krebs Cycle, they are attached to coenzyme A
- the acetyl group combines with the oxaloacetate to form the 6-carbon citrate
- coenzyme A is returned to link reaction
- citrate molecule is decarboxylated and dehydrogenated to produce 5-carbon intermediate, co2 and reduced NAD
- the 5C intermediate is decarboxylated and dehydrogenated to produce 4-carbon intermediate, co2 and reduced NAD
what happens during the Krebs cycle? (stage 6-9)
- the 4 carbon intermediate undergoes substrate level phosphorylation to make ATP from ADP+Pi
- the 4-carbon intermediate is dehydrogenated to produce reduced FAD
- the 4-carbon intermediate is dehydrogenated to produce reduced NAD
- last 3 reactions convert the 4-carbon intermediate into oxaloacetate, allows Krebs cyle to turn once more
what is a cofactor?
inorganic ions such as:
- chloride ion and amylase
- magnesium ion and DNA polymerase
what is a coenzyme?
organic molecules like vitamins, loosely bound to the enzymes
what are prosthetic groups?
inorganic ions/organic molecules that are tightly bound to enzymes
what are the products of ONE TURN of the Krebs cycle?
- 3 reduced NADs
- 1 reduced FAD
- 1 ATP
- 2 CO2 molecules
what are the coenzymes in respiration?
- NAD
- FAD
- CoA (coenzyme A)
what are NAD, FAD ABD CoA made from?
NAD - vitamin B3
FAD - vitamin B2
CoA - B5
what are the coenzymes used for in respiration?
used to move protons, electrons and functional groups between enzymes
what happens to NAD during respiration?
- NAD accepts 1 hydrogen atom and an electron OR 1 proton and 2 electrons
- NAD reduced to reduced NAD
- NAD and NAD+ are the oxidised forms
- reduced NAD and NADH are the reduced forms
what is the reaction for NAD during respiration?
NAD+ + H+ + 2e- ⇌ NADH
what happens to FAD during respiration?
- FAD accepts 2 hydrogen atoms or 2 protons and 2 electrons
- FAD is reduced to reduced FAD
- FAD is the oxidised form
- FADH2 is the reduced form
how can reduced NAD/FAD be written?
reduced NAD: NADH
reduced FAD: FADH2
what is the reaction for FAD during respiration?
FAD + 2e- + 2H+ → FADH2
what is reduced NAD/NADH used for?
- used in last stage of aerobic respiration to produce ATP from ADP + Pi
- done by oxidative phosphorylation
- 1 reduced NAD can be used to produce 3 ATP molecules