lecture 4 - TCA or Kreps cycle Flashcards
where does the TCA cycle take place?
in the mitochondria making it diff from glycolysis
- it requires oxygen so that it can oxidise and produce energy
- not every molecule in the production will be used for molecules - may be used for other functions
how is glucose converted into Acetyl coA?
pyruvate
what are the functions that the krep cycle can facilitate?
steroid synthesis, ketogenesis, FA (fatty acids) synthesis
what is a link reaction?
speed at which the reaction continues - Need to get rid of one carbon atom – reduction, remove carbon by producing carbon dioxide
Metabolic reaction is catalysed by PDH – a complex of protein structures that has the enzyme
what does it mean when the enzyme has the name dehydrogenase?
reduction reaction
how is PDH regulated?
by another enzyme - either active (non-phosphorylated) or inactive (phosphorylated)
- PDH produces PDH kinase which facilitates the ability to add another enzyme
which PDH do we want?
inactive - PDH kinase requires to be active to prevent a surplus of energy we don’t need to use
what upregulates the production of PDH kinase?
NADH, ATP, Acetyl-CoA
what does removing a phosphate group from its existing molecule mean?
increases its activity so that PDH can become active
how is PDH regulated during exercise?
it is activated during exercise and increases pyruvate
what happens when the energy cell is low?
PDH is activated
what happens when the cell is plentiful?
PDH is inhibited
what activates the TCA cycle?
PDH activation
why has the + from NAD disappeared when it is converted to NADH?
Because it has taken an electron from the hydrogen, which is negatively charge therefore it now has a neutral charge
what does the supply of NAD and FAD molecules depend on?
whether they’re available
- oxidized, activity of the electron transport chain which depends on oxygen – if we fail to deliver enough o2 we disrupt this conversion and the molecules it needs to run – dependent on the delivery of o2 – influences whether it has enough substrates to continue
how many steps are there in the TCA cycle?
8
what is step 1 of the TCA cycle?
Acetyl coA converted into citrate (Citrate can be used in other reactions to produce cholesterol and FA synthesis)
what is step 2 of the TCA cycle?
citrate converted into iso-citrate
what is step 3 of the TCA cycle?
iso-citrate into alpha-ketogluterate (to produce DNA and Proteins)
what is step 4 of the TCA cycle?
alpha-ketogluterate into succincyl coA
what is step 5 of the TCA cycle?
succincyl coA into succinate (produce porphyrins whicha re important for the production of blood cells, e.g., haemoglobin)
what is step 6 of the TCA cycle?
succinate into fumerate
what is step 7 of the TCA cycle?
fumerate into malate (gluconeogenesis)
what is step 8 of the TCA cycle?
malate into oxaloacetate (generate DNA and proteins)
