Integration of Cell Metabolism Flashcards
what molecules does muscle rely on?
carbohydrate and fatty acid oxidation
what can the brain not use as a fuel source?
fatty acids BUT can utilise ketone bodies
what is adipose tissue?
storage site for triglycerides
what molecules can the heart metabolise?
both fatty acids and carbohydrates, also ketone bodies
liver
site of many metabolic processes e.g transamination, ketone body formation (during fasting), glycolysis
body’s main carbohydrate store and a source of blood glucose
what if the brain gets too little glucose?
=hypoglycaemia which causes faintness and coma
what if the brain gets too much glucose?
=hyperglycaemia, can cause irreversible damage
during light contraction, what meets the muscles’ ATP requirements?
oxphos
vigorous contraction?
O2 becomes limiting factor, glycogen is broken down and lactate formed
can the heart respire anaerobically?
no
what can excess glucose-6-phosphate make?
glyogen in the liver
how does body avoid hypoglycaemia?
-breakdown liver glycogen stores
-release free fatty acids from adipose tissue
-convert acetyl CoA into ketone bodies via liver (the ketone bodies will be used instead of glucose, freeing up glucose for the brain)
gluconeogenesis?
basically inverse of glycolysis
generation of glucose from pyruvate
which molecules can enter gluconeogenesis?
lactate + some amino acids can form pyruvate
some amino acids can form oxaloacetate
glycerol can enter via DHAP
bypass reactions of gluconeogenesis?
some of the reverse reactions are irreversible.
we need to bypass the kinase-driven reactions,
we need 4 additional enzymes to do this
4 extra enzymes of gluconeogenesis?
pyruvate carboxylase (pyruvate to oxaloacetate)
phosphoenolpyruvate carboxykinase (oxaloacetate to phosphoenolpyruvate)
fructose-1,6- bisphosphatase ( fructose 1,6 bisp to glucose 6-phosphate)
glucose-6-phosphatase (glucose-6-phosphate to glucose)
where do the gluconeogenesis reversal reactions occur?
pyruvate carboxylase in the mitochondria, rest are cytosolic
how many phosphoanhydride bonds are needed to turn an energetically unfavourable process into an energetically favourable one?
six
deamination of all 20 amino acids gives rise to how many molecules?
just 7
glycogenic amino acids?
their skeletons can generate glucose via gluconeogenesis
ketogenic amino acids?
carbon skeletons can’t make glucose but can make fatty acids and ketone bodies
when fasting what can fatty acids be converted to?
ketone bodies
when muscle contracts, what happens?
increased glucose transporters on muscle cell membranes
what does adrenaline do?
increases rate of glycolysis in muscle by:
increasing gluconeogenesis by the liver
releasing fatty acids from adipoctyes
point of lactate synthesis?
replenishes NAD+ levels so glycolysis can continue
lactate in gluconeogenesis?
can be used to synthesize more glucose in the liver
typical blood glucose concentration?
4 mM
isoform of HK in liver and muscle
Hk 1 in muscle
Hk 4 in the liver
what is Michaelis constant?
concentration of substrate at which an enzyme functions at a half maximal rate (half of vMAX)
Muscle Hk?
high glucose affinity, makes sense as muscle cells are constantly respiring
highly sensitive to G-6-P inhibition (if there’s too much the reaction will slow down)
Liver Hk?
low glucose affinity so active at high glucose concentrations,
less sensitive to G-6-P inhibition
complications of diabetes?
