Molecular Fundamentals - Glycolysis

what is the primary fuel for energy production especially for the brain, muscles, and several other body organs and tissues?

glucose

in order to split a sugar in half, what needs to happen?

it has to be phosphorylated on both sides

how many steps is glycolysis?

10 steps

glycolysis converts glucose into what?

pyruvate

what describes glucose?

a 6-carbon molecule

what describes pyruvate?

3-carbon molecule

each cycle of glycolysis forms how many pyruvate molecules?

two

in step 1 of glycolysis, glucose used what to pass through the cellular plasma membrane?

transporters (GLUT)

where does glycolysis happen?

in the cytoplasm

what must happen to glucose in the cytoplasm in order to prevent it from leaving the cell?

it must be tagged with phosphate

what type of enzymes are responsible for phosphorylating and dephosphorylating molecules during glycolysis?

kinases (hexokinase, glucokinase, etc.)

kinase enzyme converts ATP to what during the first step of glycolysis?

ADP

which carbon of glucose is phosphorylated during the first step of glycolysis?

carbon 6 (because it is not protected by a double bond)

glucose is converted to what by hexokinase in step 1 of glycolysis?

glucose-6-phosphate

in order to be used for energy production, glucose-6-phophate must be isomerized to what during step 2 of glycolysis?

fructose-6-phosphate

during step 2 of glycolysis, the isomerization step is responsible for what?

creating the form of the molecule able to yield 2 three-carbon compounds

what enzyme causes glucose-6-phosphate to isomerized to fructose-6-phosphate?

phosphohexose isomerase

during step 3 of glycolysis, fructose-6-phosphate becomes what?

fructose-1,6-bisphosphate

bisphosphate means the phosphates are what?

separated

biphosphate means the phosphates are what?

next to each other

what enzyme converts fructose-6-phosphate to fructorse-1.6-bisphosphate in step 3 of glycolysis?

phosphofructokinase 1

what enzyme splits fructose-1,6-bisphosophate in half into DHAP and GA3P during step 4 of glycolysis?

aldolase

during step 4 of glycolysis, fructose-1,6-bisphosphate is used to form what?

DHAP and GA3P

in order to proceed with the glycolysis, DHAP needs to converted to what?

GA3P

what enzyme converts DHAP into GA3P?

triose-P-isomerase

after steps 4 and 5 of glycolysis, what are the products?

2 molecules of GA3P

during step 6 of glycolysis, NAD⁺ does what?

uses GA3P dehydrogenase to remove a hydrogen from GA3P to convert to NADH

what enzyme converts GA3P to 1,3 bisphophoglycerate during the 6th step of glycolysis?

GA3P dehydrogenase

step 7 of glycolysis is regulated by what enzyme?

phosphoglycerate kinase

during step 7 of glycolysis 1,3 bisphosphoglycerate is transformed to what?

3 phosphoglycerate

during step 8 of glycolysis, 3 phosphoglycerate is transfromed into what?

2 phosphoglycerate (phosphate moves from the 3rd carbon to the second carbon) 

during step 8 of glycolysis, what enzyme converts 3 phosphoglycerate into 2 phosphoglycerate?

phosphoglycerate mutase

during step 9 of glylcolysis, what enzyme converts 2 phosphoglycerate into phosphoenolpyruvate?

enloase (removes H₂O to make weak)

during step 9 of glylcolysis, 2 phosphoglycerate is transformed into what?

phosphoenolpyruvate

during step 10 of glycolysis, phosphoenolpyruvate is transformed into what?

pyruvate

during step 10 of glycolysis, what enzyme transforms phosphoenolpyruvate into pyruvate?

pyruvate kinase

what is the end products of glycolysis?

2 molecules of pyruvate and 2 molecules of ATP

what is the net production of ATP during glycolysis?

2 ATP molecules

in the presence of O₂, pyruvate is transformed to what?

acetyl-CoA

acetyl-CoA reacts in first step of what?

the Krebs cycle

where does Krebs cycle occur?

in the mitochondria

in the absence of O₂, pyruvate is converted to what?

lactate (lactic acid) by NADH oxidizing to NAD+ by lactate dehydrogenase

what enzyme converts pyruvate to lactate in the absence of O₂?

lactate dehydrogenase

how is lactate removed from circulation?

uptake by the liver to produce more glucose or ATP depending on body demand

lactic acidosis occurs when what?

lactic acid production exceed clearance of lactic acid

what are causes of lactic acidosis?

• increase production of pyruvate

• impaired mitochondrial utilization of pyruvate

• states of NADH accumulation

type A lactic acidosis occurs due to what?

impaired oxygenation of tissue caused by hypovolemia, cardia failure, or cardiac arrest (heart not working well)

type B lactic acidosis occurs due to what?

NOT impaired oxygenation of tissue, ex: diabetes, alcoholism, mitochondrial dysfunction