Metabolic integration

Question 1

central hubs in metabolism

Answer 1

acetyl coA: produced in glycolysis/ beta oxidation/breakdown of ketogenic a.a. and used in TCA/ketogenesis/lipogenesis
glucose 6-P: produces in glycolysis/gluconeo/glycogenolysis and used in glycolysis/glycogenesis/PPP/gluconeo

Question 2

acetyl coA/ glucose 6-p in liver in the fed state

Answer 2

glucose 6-p: produced from glucose, can enter glycolysis or glycogenesis
acetyl coA: produced from glycolysis, enter TCA or lipogenesis

Question 3

acetyl coA/ glucose 6-p in liver in fasted state

Answer 3

glucose 6-p: from glycogenolysis, proteolysis to make pyruvate, feeds into gluconeogenesis
acetyl coA: from beta oxidation, feeds into Krebs and ketone bodies

Question 4

positives of compartmentalisation

Answer 4

cluster related functions serving a common purpose
isolation allows for regulation
removal of potentially harmful processes

Question 5

negatives of compartmentalisation

Answer 5

transport mechanisms required, need intrinsic proteins to each compartment

Question 6

example of compartmentalisation - glujconeogeneis

Answer 6

starts in mt 
then in cytosol
then into ER 
across plasma membrane 
need transporters across each membrane

Question 7

importance of metabolic control between tissues

Answer 7

most tissues don’t metabolically exist in isolation
requires substrate to be supplied from somewhere and products removed
avoid wasting fuel
allows for tissue specialisation and for a ‘signal’ to be generated in one location and act on peripheral tissues

Question 8

cori cycle

Answer 8

liver with other tissues like renal medulla/ RBC/ anaerobic muscle
cells produce lactate, then transported to liver and converted into glucose using gluconeogenesis, saves fuel

Question 9

glucose-alanine cycle

Answer 9

muscle break down protein, mostly releasing alanine and glutamine
liver can use as substrates for glujconeogeneis

Question 10

how is regulation of pathways mainly achieved

Answer 10

changing levels of enzyme/protein activity

Question 11

acute regulation 1- internal signal

Answer 11

intracellular signal
often allosteric
eg. PFK-1 inhibited by ATP and activated by AMP

Question 12

acute regulation 2-external signal

Answer 12

whole body signal, so can regulate multiple pathways simultaneously
often acts at cell surface receptor and induces internal response
eg. hormones - insulin, glucagon and adrenaline
often act through phosphorylation

Question 13

functions of hormones

Answer 13

signal to metabolism in distant tissues

nutritional status and energy needs

Question 14

insulin stimulated by

Answer 14

increased blood glucose, certain aa and FA

Question 15

insulin increases

Answer 15

anabolic reactions
glucose uptake and glycolysis
glycogenesis
de novo lipogenesis
fatty acid uptake and storage in adipose
protein synthesis

Question 16

insulin inhibits

Answer 16

gluconeogenesis
glycogenolysis
fatty acid mobilisation by HS;L from adipose
ketogenesis
protein breajdown 
(affects all fuels, not just glucose)

Question 17

glucagon overall actions

Answer 17

stimulated by low glucose, fasted state
only acts on the liver!!
liberate glucose into the blood from liver

Question 18

adrenaline overall actions

Answer 18

divert substrates towards making ATP

Question 19

chronic regulation of metabolism

Answer 19

transcription or translation, takes longer but is longer lasting

Question 20

insulin chronic regulation

Answer 20

increases synthesis of glycogen synthase and glycolytic enzymes
decreases synthesis of specific gluconeogenic enzymes (pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6 bisphosphatase and glucose 6 phosphatase)

Question 21

futile cycling

Answer 21

need to avoid simultaneously breaking down and synthesising the same product
use reciprocal regulation