Ch 13.1 Glycolysis Flashcards
What is the role of ATP in coupled processes?
ATP is often involved in coupled processes.
What does ATP hydrolysis provide energy for?
ATP hydrolysis provides the energy for glucose phosphorylation.
Why does ATP hydrolysis release so much energy?
The ATP hydrolysis products are more stable than the reactants, making its hydrolysis reaction highly exergonic (ΔG ≪ 0).
What is one reason thioester hydrolysis releases a large amount of free energy?
Thioester hydrolysis is more exergonic than the hydrolysis of an ordinary (oxygen) ester.
What is activation in metabolic pathways?
Activation is the formation of a more reactive, higher energy substance that causes the next reaction to be exergonic.
What is coenzyme A (CoA-SH)?
Coenzyme A is a key co-enzyme in biochemical pathways.
What happens to molecules added to the sulfhydryl end of Coenzyme A?
Molecules can be added as a priming step for their subsequent release in an exergonic step.
What vitamin is ascorbic acid and what is its biochemical function?
Ascorbic acid (C) is a cofactor for hydroxylation of collagen.
What is the human deficiency disease associated with ascorbic acid?
Scurvy.
What is the function of biotin (B7) in metabolism?
Biotin is a cofactor for carboxylation reactions.
What is the human deficiency disease associated with cobalamin (B12)?
Anemia.
What does folic acid function as in biochemical reactions?
Folic acid is a cofactor for one-carbon transfer reactions.
What is the human deficiency disease associated with folic acid?
Anemia.
What is lipoic acid’s role in metabolism?
Lipoic acid serves as a cofactor for acyl transfer reactions.
What does nicotinamide (B3) do in biochemical pathways?
Nicotinamide is a cofactor for oxidation-reduction reactions.
What is the human deficiency disease associated with niacin (B3)?
Pellagra.
What is the role of pantothenic acid (B5) in metabolism?
Pantothenic acid is a cofactor for acyl transfer reactions.
What is the function of pyridoxine (B6) in biochemical reactions?
Pyridoxine is a cofactor for amino-group transfer reactions.
What is the role of riboflavin (B2) in metabolism?
Riboflavin acts as a cofactor for oxidation-reduction reactions.
What is thiamine (B1) required for in metabolism?
Thiamine is a cofactor for aldehyde transfer reactions.
What is the human deficiency disease related to thiamine?
Beriberi.
How can cells regulate flux through a metabolic pathway?
By adjusting the rate of a reaction with a large free energy change.
What are the goals of glycolysis?
- Formation of high-energy molecules (ATP and NADH) as cellular energy sources
- Production of pyruvate for additional ATP and NADH from the citric acid cycle
- Production of six- and three-carbon intermediate compounds for other cellular purposes.
What is the first phase of glycolysis known as?
The investment phase.
What type of reaction occurs in the first five steps of glycolysis?
Investment phase reactions.
What mnemonic can help remember the steps of glycolysis?
Goodness Gracious Father Franklin Did Go By Picking 2 Pumpkins to Prepare Pie.
What is the first enzyme involved in glycolysis?
Hexokinase.
What type of reaction does phosphoglucose isomerase catalyze?
Isomerization.
What is the key regulatory enzyme in glycolysis?
Phosphofructokinase.
What does fructose-2,6-bisphosphate do in glycolysis?
It is the most potent activator of phosphofructokinase in mammals.
What is the reaction catalyzed by aldolase in glycolysis?
Fructose-1,6-bisphosphate is split into two 3-carbon fragments.
What type of reaction does triose phosphate isomerase catalyze?
Isomerization.
What is the result of the GAP dehydrogenase reaction?
Oxidation of glyceraldehyde-3-phosphate, reducing NAD+ to NADH.
What is substrate-level phosphorylation?
The transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP.
What type of reaction is catalyzed by enolase?
Dehydration of 2-phosphoglycerate to form phosphenolpyruvate (PEP).
What happens during the pyruvate kinase reaction?
Conversion of PEP to pyruvate with the production of ATP.
What is the net equation for glycolysis?
C6H12O6 + 2 NAD+ + 2 HPO4^2- + 2 ADP → 2 C3H4O3 + 2 NADH + 2 ATP + 2 H2O + 2 H+.
What three reactions exhibit particularly large decreases in free energy during glycolysis?
The specific reactions are not detailed in the text.
What are the main products of glycolysis?
2 Pyruvate, 2 NADH, 2 ATP, 2 H2O, 2 H+
Glycolysis converts glucose into pyruvate while producing NADH and ATP.
Which reactions in glycolysis exhibit large decreases in free energy?
Hexokinase (HK), Phosphofructokinase (PFK), Pyruvate kinase (PK)
These reactions are exergonic and are key control points in glycolysis.
What is the role of hexokinase in glycolysis?
Catalyzes the first step of glycolysis
Hexokinase initiates the conversion of glucose to glucose-6-phosphate.
What is the role of phosphofructokinase in glycolysis?
Catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate
PFK is a key regulatory enzyme in glycolysis.
What is the role of pyruvate kinase in glycolysis?
Catalyzes the conversion of phosphoenolpyruvate to pyruvate
PK is another crucial regulatory point in glycolysis.
How is pyruvate kinase activated?
Activated by fructose-1,6-bisphosphate (F1,6BP)
This is an example of feedforward activation.
What inhibits pyruvate kinase?
ATP
High levels of ATP signal sufficient energy, inhibiting PK.
What happens to pyruvate in aerobic organisms?
Converted to acetyl CoA for entry into the citric acid cycle
Pyruvate is a key metabolite linking glycolysis and the citric acid cycle.
What is a fate of pyruvate during intense exercise?
Converted to lactate
This process helps regenerate NAD+ and is sometimes referred to as the eleventh step of glycolysis.
What is the significance of lactate conversion?
Regenerates NAD+
This is crucial for maintaining glycolysis under anaerobic conditions.
Who coined the term fermentation?
Louis Pasteur
He described fermentation as life processes occurring without air.
What is the precursor of oxaloacetate?
Pyruvate
Oxaloacetate is important for gluconeogenesis and amino acid synthesis.
Fill in the blank: The three main enzymes that control glycolysis are hexokinase, phosphofructokinase, and _______.
pyruvate kinase
True or False: Pyruvate can be further oxidized to produce acetyl CoA.
True
What type of control do the enzymes in glycolysis exhibit?
Allosteric control
This allows for regulation based on the cell’s energy needs.
What is the mechanism of pyruvate carboxylase?
Utilizes a vitamin to transfer a COO- group
This enzyme is involved in converting pyruvate to oxaloacetate.
what are the energetic cliffs in glycolysis?
hexokinase, phosphofructokinase, and pyruvate kinase
why are hexokinase, phosphofructokinase, and pyruvate kinase candidates for metabolic regulation?
because they are far from equilibrium, they are committed steps with very favorable change in energy
