nonaerobic carbohydrate metabolism Flashcards
main precursor of ATP
glucose (can also be FA and proteins)
substrate level phosphorylation
phosphate is taken from one molecule and applied to adp to form ATP
oxidative phosphorylation
energy obtained from proton graident as oxygen is reduced to power ATP synthesis
where does the power to activate atp synthesis come from
NADH and FADH2`\
ways that glucose can enter blood stream
- abosrption from small intestine
- liver and kidney cells perform glycogenolysis and gluconeogenesis
glucose receptors
allow glucose to be taken into cells from blood
GLUT 1
baseline glucose intake
GLUT 1
baseline glucose intake
glut 2
liver, pancreatic beta cells, kidney cells
- bilateral transporter necessary for gluconeogenesis
glut 3 transporter
neurons and placenta
- high affinity transporter
GLUT 4
cardiac and skeletal muscle and adipose
- regulated by insulin
- exoressed when bgl is high to bring it back down
insulin resistnace
high blood glucose levels can lead to insulin spikes often and cells become desensitized to glucose and wont secrete glut 4
what does insulin activate
uptake of glucose into cells from the blood to decrease BGL
what does glucagon activate
release of glucose into blood from cells to increase BGL
besides glucagon, what else can increase BGL
epinephrine, cortisol, norepinephrine
glycolysis occurs
in cytoplasm of all cells (prokaryotes and eukaryotes)
net equation of glucolysis
1 glucose + 2 atp –> 2 pyruvate + 2 NADH + 2 ATP
pyruvate
3 carbon alpha keto acid product of glycolysis
is breakdown of atp to adp exergonic or endergonic
highly exergonic , favorable reaction that is often coupled to others
step 1 of glycolysis
glucose to glucose 6 p via hexokinase
- requires 1 atp
function of g6p
traps glucose in the cell
step 2 of glycolysis
glucose 6p –> f6p via glucose 6 p isomerase
step 3 of glycolysis
commited step of glycolysis
f6p –> 1,6 fructobisphosphate via PFK-1
- require 1 atp
step 4 of glycolysis
F1,6BP –> glyceraldehyde 3 p and DHAP
- fructose bisphosphate aldolase
step 5 of glycolysis
DHAP –> glyceraldehyde 3 p via triosephosphate isomerase
step 6
pay off phase
- Glyceraldehyde 3 p –> glyceraldehyde 1,3 bisphosphate via glyceraldehyde phosphate dehydrogenase
step 7 of glycolysis
1,3 BPG –> 3 phosphoglycerate
- 1 atp made
- enzyme: phosphoglycerate kinase
step 8 of glycolysis
3 PG –> 2 phosphoglycerate
- phosphoglycerate mutase
step 9 of glycolysis
2PG –> PEP via enolase
step 10
how is NAD+ regenerated in anerobic organisms
fermentation
ethanol fermentation
- pyruvate is converted acetaldehyde (-co2) via pyruvate decarboxylase
- alcohol dehydrogenase converts acetaldehyde to ethanol and regenerates nad+
lactic acid fermentation
pyruvate converted to lactate via lactate dehydrogenase and nad+ remade
- muscle
where does gluconeogenesis occur
kidney (adrenal cortex) and liver
starting material of gluconeogenesis
pyruvate
possible precursors for gluconeogenesis
amino acids, pyruvate, fatty acids
function of pyruvate carboxylase
convert pyruvate to oxaloacetate during first step of gluconeogenesis , oxaloacetate is converted into malate for transport out of the cell and then changed back
function of PEP carboxykinase
converts oxaloacetate into PEP during the second step of gluconeogenesis
function of F16BP
catalyzes conversion of F16 bp into F6p
- removes phosphate
glucose 6 phosphatase function in gluconeogeneiss
G6p –> glucose
primary stores of glycogen
liver and muscle
glycogenin
core protein that serves as base for glycogen synthesis
linear linkages of glycogen
alpha 1-4
branched linkages of glycogen
alpha 1-6
what is the starting point for glycogenesis
Glucose 6 p (same as glycolysis)
phosphoglucomutase
converts G6p to G1P for glycogenesis
what is G1P converted into for glycogenesis
UDP glucose
UDP glucose
nucleotide sugar that donates glucose to growing glycogen strand via glycogen synthase
what bond does glycogen synthase create
alpha 1-4 bonds
glycogen branching enzyme
creates alpha 1-6 bonds on growing glycogen molecule
function of glycogenin
primer that helps catalyze the first 8 glucose molecules of a glycogen chain, then glycogen synthase takes over
what enzyme catalyzes glycogenolysis
glycogen phosphorylase
- breaks up alpha 1-4 bonds
result of phosphorolysis in glycogenolysis via glycogen phosphorylase
G1P molecules
glycogen debranching enzyme
removes alpha 1-6 bonds from glycogen
PPP
shunt G6P away from glycolysis/gluconeogenesis and use it for amino acid synthesis and NADPH
major products of PPP
NADPH and ribose 5 phosphate
major functions of NADPH
important reducing agent used in lipogenesis and nucleic acid formation
major functions of ribose 5 P
used in nucleic acid synthesis
two main stages of PPP
oxidative and nonoxidative
oxidative phase of PPP
g6p is converted into 6 phosphogluconolactone via glucose 6 phosphate dehydrogease to produce 1 NADPH and is RATE limiting step of ppp
important function of oxidative phase of ppp
main products of ppp are generated in oxidative phase (ribose 5 p and NADPH)
and a carbon is lost
nonoxidative phase of ppp
allows cells that do not need ribose 5 p to process and feed back into glycolysis
- sugar is rearranged back into F6P and then G6P
is glycolysis upregulated when atp levels are low or high
low
what inhibits glycolysis
high levels of atp and nadh , also high levels of citrate
buildup of acetyl coA and pryuvate cause what process to begin
gluconeogenesis
regulatory points of glycolysis
- hexokinase
- PFK-1
- pryuvate kinase
what downregulates PFK-1
increased ATP levels and citrate
what inhibits PK
increased ATP and acetyl coA
regulation of Pryuvate carboxylase and PEP carboxykinase
induced by excess acetyl coA
what inhibits Fructose 1-6 bisphosphotase
increased AMP levels
what compound allosterically regulates both PFK-1 and F16 bispohosphatese
fructose 2,6 bisphosphate
high levels of f26bp induce which enzyme
PFK-1
what does PFK2 produce
fructose 26 bisphosphate
effect of glucagon on pfk2
inhibits pfk2 and promotes f16 bisphosphotase
effect of insulin on pfk2
stimulates pfk2 and promotes pfk1/ glycolysis
which hormone regulates glycogen phosphorylase in muscke
epinephrine
- release g1p for glycolysis
which hormones regulate glycogen phosphorylase in liver
glucoagon
calcium effect on glycogen phosphorylase in muscle
upregulates glycogen phosphorylase along with amp
insulin effect on glycogen synthase
upregulates
