Glycolysis Flashcards
Where do glycolysis take place
In cytosol
Does glycolysis require oxygen
No , can function either in the
presence of oxygen (aerobically) or in the
absence of oxygen (anaerobically)
What is the end product of glycolysis
Pyruvate
What are the 2 general functions of glycolysis
Provides ATP
Provides intermediate for other pathways
What role does glycolysis play in red blood cells
Exclusive source of energy because RBC lacks
mitochondria
What role does glycolysis play in skeletal muscles
Source of energy during exercise
What role does glycolysis play in liver and adipose tissue
Triglyceride (source of glycerol phosphate) and fatty acid (source of acetyl-CoA) synthesis
What is the enzyme that changes glucose into glucose 6 phosphate
Hexokinase
Can glucose exit the cell after get converted into g6p
No, Cells trap glucose by phosphorylating it,
preventing exit on glucose carriers
Glucose -6-P cannot diffuse through the membrane
What is the name of the isoenzyme of hexokinase . And which one has a higher affinity for glucose .
Glucokinase = Isoenzyme of hexokinase
Hexokinase has a higher affinity for glucose
In what cells do we find glucokinase
Liver, beta cells of pancreas
What 2 pathways glucokinase (isoenzyme of hexokinase)is used in
Provides glucose-6-P for glycogen synthesis and
lipogenesis [when glucose is in excess of
requirement for glycolysis]
What is the enzyme for the rate limiting step of glycolysis?
Phosphofructokinase (PFK)
What can occur if there is a deficiency in pfk ?
Deficiency of PFK-1 = increases insulin resistance and thus develops Ty p e 2 diabetes)
PFK creates what product
Fructose 1-6 Bis P
What is significant about step 6 of glycolysis
This is the only step in Glycolysis in which NAD+ is reduced to NADH
Glycolysis makes ATP via _________ phosphorylation
Substrate level phosphorylation
What is significant about step 7 in glycolysis
ATP created
What is significant about step 10 of glycolysis
ATP generated via substrate level phosphorylation
What enzyme is involved in step 10 of glycolysis
Pyruvate kinase
How many ATPs are invested in glycolysis
2
What inhibits hexokinase
The product ( Glucose 6 Phosphate)
How many NADH and ATP are generated in the payoff phase of glycolysis
2 NADH, 4 ATP
What is the net gain of ATP per molecule of glucose in glycolysis
2 molecules of ATP per molecule of glucose
How many NADH are produced in glycolysis
2
First site of ATP formation (Reaction 7) may be bypassed in _______
First site of ATP formation (Reaction 7) may be bypassed in RBC
Name the enzyme for the bypass route for reaction 7 , under what circumstances does this occur?
Bisphosphoglycerate mutase catalyzes
• 1,3-bisphosphoglycerate —> 2,3bisphosphoglycerate
This occurs is red blood cells
What are the bypass results from reaction 7 of glycolysis
No net yield of AT P from glycolysis
2,3-bisphosphoglycerate binds to hemoglobin
Thus decreasing the affinity of hemoglobin to bind
oxygen
Making oxygen more readily available to tissues
What is significant about 2-3 bisphosphoglycerate
It is the product in step 7 of glycolysis that occurs in Red blood cells. This product binds to hemoglobin , so that it cant bind to oxygen. This makes oxygen more readily available in the the tissues
How many regulatory steps are there in glycolysis
3
What are the 3 enzymes involved in the regulatory steps of glycolysis
- Hexokinase
- Phosphofructokinase
- Pyruvate Kinase
Hexonkinase is _______ by glucose 6 phosphate
Inhibited
The inhibition of hexokinase is known as _____ inhibition
Product inhibition
Phosphofructokinase is the ____ step of glycolysis
Rate limiting
List the 2 inducible enzymes for PFK
Inducible enzyme:
- Induced in feeding by insulin
- Repressed in starvation by glucagon
Name 2 types of allosteric regulation that inhibit PFK
Citrate, ATP
In terms of allosteric regulation list to enzymes that activate PFK
Fructose 2-6 bisphosphate Bis P, AMP
The production of which molecule will be directly affected in someone with type 1 diabetes
Fructose 1-6 BP
Would PFK be activated during a MI?
During a myocardial infarction, the oxygen supply to an
area of the heart is dramatically reduced. Under these
anaerobic conditions, phosphofructokinase would be
activated by increased levels of intracellular AMP
The fate of pyruvate depends on what
It depends on the redox state of the tissue, ( if o2 is available or not)
What happens to pyruvate under anaerobic conditions
Anaerobic condition (e.g. in exercising muscle,
RBC)
•Formation of lactate by lactate dehydrogenase
What is the fate of pyruvate during aerobic conditions
Aerobic condition
•Enters mitochondria •Formation of acetyl coA via citric acid cycle
Is lactate formed under aerobic or anaerobic conditions
Anaerobic
Is acetal coa formed under aerobic or anaerobic conditions
Aerobic
The transformation of pyruvate to lactate is an oxidation or reduction reaction
Reduction
What is the name of the enzyme involved in pyruvate going to lactate I
Lacatate Dehydrogenase
____ is derived from the vitamin Niacin
NAD+
What structure does pyruvate enter
Mitochondria
What occurs in the PDC
Oxidative decarboxylation of pyruvate produces acetyl-CoA by
pyruvate dehydrogenase enzyme complex
What is the name of the substrate the enters the citric acid cycle
Acetyl coa
Are any ATP produced in the conversion of pyruvate to acytal coa
No!
What is produced during the conversion of pyruvate to acetal coa
NADH
How many enzymes are found in the PDC
It’s a MULTI ENZYME complex, so it has 3
List 3 advantages of having a multi enzyme complex
- Higher rate of reaction
- Minimum side reaction
- Coordinated control
Is acytal coa an inhibitor or activator of PFK?
Inhibitor !
How many molecules of oxygen (O 2) are required to complete the
reactions of aerobic respiration beginning with four molecules of glucose?
Glucose = C6H1206
We have 6 oxygens x 4 molecules = 24
Impaired pyruvate metabolism can lead to
Lactic acidosis
Lack of pyruvate kinase can lead to
Hemolytic anemia
What does high AMP signal
Low energy , need ATP generation
High levels of ATP and citrate
Glycolysis inhibited
