N: CARB: metabolism Flashcards
define catabolism:
breakdown of larger molecules into smaller
eg. glycogen -> glucose ***yields energy
where do metabolic reactions take place?
inside cells
eg. liver, muscle cells
define anabolism:
build up of smaller molecules into larger
eg. amino acids -> protein ***needs energy
understand the role of ATP energy provision
learning objective
ADP + P => ATP => ADP + P
(APP+P) (APPP)
- energy is stored in high energy phosphate bonds
- energy in the last 2 bonds most important
how many ATP does glucose make?
1 glucose yields 32 ATPs
what are coenzymes?
protein catalysts specific to metabolic reactions
stages involved in converting glucose energy into ATP?
1) glycolysis (sugar splitting)
pyruvate -> acetyle-CoA (aerobic) no oxygen? pyruvate -> lactic acid
2) Tricarboxylic Acid Cycle (high energy intermediates NADH&FADH2)
3) Electron Transport Chain - uses NADH & FADH2 transfer into ATP
describe glycolysis:
glucose -> 2 pyruvate
co-enzyme needed to gain H+
2NAD+ -> 2NADH(substituted into electron transport chain)
2 ATP used but 4 ATP created so net gain of 2ATP during glycolysis
what is the electron transport chain? where does it occur?
it is a series of proteins that use the H+ gradient to produce ATP
inner membrane of mitochondrion
what happens to the 2 pyruvates produced by glycolysis?
2 pyruvate + CoA -> 2CO2 + 2 Acetyl-CoA
these 2 acetyl-CoA’s go into TCA cycle
make either fats when energy is plentiful OR
generate ATP when cell is low in energy via. TCA cycle
what co-enzymes does conversion of pyruvate -> acetyl-CoA need?
1) CoA - co-enzyme A
2) TPP - thiamine pyrophosphate -> vit B1 thiamine
3) NAD+ -> vit B3 niacin
what is pyruvate converted to?
either
a) acetyl-CoA - oxygen available - CO2 produced
b) lactic acid - no oxygen - fermentation
this depends on oxygen availability
if plenty of energy is available what can acetyl-CoA be converted into?
fatty acids
why can acetyl-CoA not be produced if no oxygen is available?
no oxygen means NAD+ depleted therefore conversion to acetyl-CoA prevented
pyruvate will accumulate(in muscle) and converted to lactic acid which will produce NAD+ => which will allow glycolysis to continue
where is lactic acid converted back to glucose?
after build up in muscle goes to liver to be converted back to glucose
what is termed the most vital substance in the TCA cycle and where does it come from?
oxaloacetate
comes from adequate carb intake
describe the TCA cycle:
- this is what acetyl-CoA feeds into, it combines with oxaloacetate to make H+
- H+ created will then combine with cofactors: NAD+ & FAD
- this makes high energy intermediates NADH & FADH2
- NADH & FADH2 feed into electron transport chain
understand importance of oxaloacetate in primary the TCA cycle
***** like always an exam question
- oxaloacetate is the first and last step in the TCA cycle
- it combines with acetyl-CoA to produce citrate
- its made from CARBOHYDRATE (glucose -> pyruvate)
- oxaloacetate cannot be made from fat
- therefore adequate carb intake vital to efficiently metabolise fat
what does the electron transport chain utilise to make energy?
the H+ pH gradient
what reaction happens in the ETC?
high energy intermediates are combined with oxygen to make water and energy-ATP
2NADH & FADH2 + O2 -> H2O
=> 4H + O2 -> 2H2O **energy madeeee
where does glycolysis occur?
outside cell!
the only part of the metabolism process to occur not within mitochondrion
in the ETC high energy intermediates made in the TCA cycle need to pass through multiple membrane proteins where they “give” H+
what are these proteins in order?
1) flavoprotein
2) co-enzyme Q
3) cytochrome b
4) cytochrome c
5) cytochrome a
where does NADH give up its H in the ETC?
at the first protein on the inner membrane of the mitochondiron
FLAVOPROTEIN
where does FADH2 give up its H on the ETC?
on the second protein/co-enzyme
CO-ENZYME Q
why do NADH and FADH2 give their H atoms at different points in the chain?
as they have different energies
FADH2 has less energy than NADH as it comes later in the chain
general steps in carb metabolism:
carb
- > glucose
- > pyruvate
- > acetyl-CoA
- > TCA cycle
- > ETC => ATP!!! oh and water haha
