Regulation of glycolysis and gluconeogenesis Flashcards
what is the first step that involves loss of ATP?
hexokinase/ glucokinase
When hexokinase is not needed for the formation of Glucose 6-P what is already available?
Glucose 1-P is available and the net production of glycolytic ATP is increased
what is gluckokinase a isozyme of?
hexokinase IV
what cells are glucokinase in and not at the cellular level?
beta cells of the islets of langerhans in the pancreas
glucokinase allow recognition of high blood glucose levels and will lead to the release of what hormone?
insulin
when does hexokinase work?
when the is free glucose in the blood stream
does glucokinase want to trap alot of glucose trapped in the liver?
yes
what can the genetic deficiency of glucokinase lead to ?
maturity onset diabetes of the young type 2 ( MODY) which is charaterized by impaired insulin secretion from beta cells
are patients normally overweignt when having MODY?
no
is glucokinase inhibited by the product (glucose 6p)?
no
is hexokinase inhibited by the product glucose 6P?
yes , when most of the glucose is trapped in the liver there is not alot of glucose in the blood stream giving hexkinase the chance to trap it in the cell
does gluckinase have a large affinity for glucose?
no
does glukokinase have a large vmax?
yes
the Km is blank times the value for normal blood glucose levels?
2x
why is glucokinase needed in the liver?
for the reduction of high glucose levels after a carbohydrate rich meal
does glycolysis need to occur at normal ATP levels?
no glycolysis occurs when there is a carbohydrate rich meal or if there is low ATP levels
How is inhibition of ATP overcome when the bifunctional enzyme is present?
it is overcome by the production of PFK2 making fructose 2,6 bisphophate
when you have an increased amount of AMP in the cell how can PFK-1 inhibition be overcome in the commited step of glycolysis?
by ATP
does having high amounts of AMP in the muscle mean that there is muscle damage?
no when the muscles contract ATP is used and AMP is released to be recycled
when there is low levels of AMP in the skeletal muscle what is activated to get energy?
glycolysis and glycogen degradation
AMP levels in skeletal muscle does not mean that there is damage in the musles, but in the liver it does( derivation of ATP), which process is activated to produce ATP?
glycolysis is activated and gluconeogenesis is inhibited by fructose 2,6 bisohosphate which can be formed in the skeletal muscle, heart , and liver by the bifunctional enzyme( PFK2)
pyruvate kinase is inhibited by ATP and this ATP inhibition is overcome by fructose 1,6 bisphosphate. What type of activationis this?
this is a typical feed-forward activation of a pathway
in the heart, what activates glycolysis in order to link glycogen degradation to the TCA cycle for additional extra energy output?
epinephrine
in the skeletal muscle, PFK2 activity always forms blank for optimal glycolysis during muscle contraction?
fructose 2,6 bisphosphate
how is gluconeogenesis regulated for the pathway which is mostly provided by degradation of fatty acids in mitochondria?
the availability of energy
what does beta oxidation generate and lead to?
FADH2, NADH, and it leads to ATP formation in the ETC and oxidative phosphorylation
when is sever hyperclycemia found in patients?
patients with defective transport of fatty acids into the mitochondria(CARNITINE SHUTTLE) or a deficient enzyme of the fatty acid degradation spiral
what are the substrates of gluconeogenesis?
lactate, amino acids, and glycerol
which proton carrier is needed to fuel and favor gluconeogenesis?
NAD+
what other hormone besides glucagon induces PEP carbosykinase?
cortisol
to allow the usage of of PEP for gluconeogenesis what enzyme is inhibited in the presence of glucagon phosophorylation?
pyruvate kinase
what hormone is activated when dephosphorlation occurs?
insulin
what hormone is favored when phosphorylation is occuring?
glucagon
which part of the bifucntional enzyme is used when glucagon is present?
fructose bisphosphatase 2
insulin is present, what part of the bifunctional enzyme is active?
PFK2
what does alanine inhibit?
pyruvate kinase
what does glucose 6 phosphate inhibit?
hexokinase
what does fructose 6 phosphate inhibit?
glucokinase
what activates hepatic protein kinase?
frucotse 1,6 bisphospate
what does acetyl CoA activate?
pyruvate carboxylase
when there are high level of ATP, what enzymes are inhibited in glycolysis?
PFK1 and pyruvate kinase
when AMP and fructose 2,6 bisphosphate are present what is inhibited?
gluconeogenesis
does pyruvate dehydrogenase complex and the TCA cycle occur in gluconeogenesis?
no beta oxidation does
