Biochemistry of Metabolism Flashcards
what is an overview of metabolism?
change energy form
create pyruvate
acetyl coA
feeds into the citric acid cycle
liberates 8e- attached to an e- receptor
what is ATP?
the primary cellular energy carrier through triphosphate group
free energy donor
essential for all bioenergetic functions
energy rich as 2 phosphoanhydride bonds
what is ATP a free energy donor to the processes of?
anabolism / biosynthesis
mechanical work / movement
active molecular transport
atp hydrolysis
atp + h2o –> adp + Pi + H+
atp + h2o –> amp + PPi + H+
what are metabolic pathways divided into?
anabolic reactions
catabolic reactions
combination of both fundamental for function
what are anabolic pathways?
biosynthetic
reductive
require an energy source, reducing equivalent and precursor molecules
what are catabolic pathways?
degrade
oxidative
provide energy, reducing equivalents and precursors
break things down so are oxidative
what is an energy balance?
have to have the right balance of energy
healthy diet comes into play
diet + products of anabolic pathways must be balanced by catabolic pathways
what is an energy imbalance?
anabolic process greater
can lead to metabolism type disorders
how can energy balance be regulated?
diet
exercise
loss leads to obesity and type 2 diabetes
what are the fates of each dietary component?
oxidation for energy (catabolism)
storage then release
conversion into something more useful
equations for conversion of glucose
lactose —> galactose + glucose
sucrose —> fructose + glucose
key points about aerobic glucose metabolism
intermediates taken off for storage
utilises the e- transport chain and oxidative phosphorylation
carried out in cytoplasm and mitochondria
produce majority of ATP
key points anaerobic glucose metabolism
allows production of atp in cells without mitochondria
production in absence of oxygen
lactic acid
pyruvate converted to lactate
lactate causes muscle fatigue
what is glycolysis?
conversion of glucose to pyruvate
glucose —> pyruvate + 2ATP
provides rapid energy source
small yield of ATP produced
have to pay lactate back through oxidate phosphorylation
what are the stages of glycolysis?
1: investment stage
- energy consumes to convert glucose into 2 3C sugar phosphates
2: investment stage continued
oxidation of glyceraldehyde 3-phospahte
3: energy generation stage
every reaction happens twice
explain stage 1 of glycoslysis
- glucose receives phosphate group from ATP
- glucose 6- phosphate isomerism
- fructose.-6- phosphate is phosphorylated
uses 2 molecules of ATP
first reaction commits glucose to the pathway
second reaction changes structure
third reactions uses phosphate
stage 1 glycolysis
glucose —> glucose-6-phosphate —> fructose-6-phosphate —> fructose -1, 6- bisphosphate
explain stage 2 of glycolysis
fructose 1,6-bisphosphate cleaved into 2 x 3C molecules
isomers
cleaved by aldolase to give 2 compounds
dihydroxyacetone phosphate is dead end product
glyceraldehyde 3-phosphate will continue
stage 2 glycolysis
fructose -1, 6-bisphosphate —> glyceraldehyde 3-phosphate + dihydroxyacetone phosphate
explain stage 3 glycolysis
generation of physophorylated 1,3-bisphosglycerate via oxidation of the aldehyde group
phosphorylation group shifted from 3C to 2C position
reaction happens twice
creates 4 ATP, but 2 already used so only net gain of 2ATP
stage 3 glycolysis
1,3-bisphosphoglycerate —-> 3-phosphoglycerate —> 2-phosphoglycerate —> phosphoenolpyruvate —> pyruvate
glucose + ATP —> glucose-6-phosphate +ADP
6C ring converted to 5C
generates fructose
catalysed by hexokinase
traps glucose
uses ATP
irreversible
fructose-6-phosphate + ATP —> fructose-1,6-bisphosphate + ADP
uses ATP
creates ADP
rate limiting step
catalysed by phosphofructokinase
irreversible
uses ATP
rate limiting control point
