Second Half F24 II: Lecture Slides 80 - 99 Flashcards
What will the complete oxidation of glucose produce?
H2O and CO2
What are the three stages of the complete oxidation of glucose?
1.) Glycolysis and Pyruvate Dehydrogenase
2.) Citric Acid Cycle
3.) ETC
What is the polarity of Glucose?
Glucose is hydrophilic
Why can a glucose molecule not diffuse across a membrane?
Due to its hydrophilic properties
What molecules catalyze glucose import?
Transporter proteins called GLUTs, residing in the cell membrane
What is the many actions of the hormone insulin?
To stimulate GLUT mediated glucose uptake in skeletal muscles and adipose tissue.
What is the GLUT-4 transporter?
Specific transporter for insulin and only functioning in the presence of insulin
What happens in diabetes?
Blood Glucose is not taken up into the cells adequately.
What is the fasting [blood glucose] in the body?
Approximately 5mM
What cell types depend solely on glycolysis?
- Red Blood Cells
- Renal Medulla
- Brain
- Sperm
What is glycolysis the only pathway known to be able to do?
Provide energy under anaerobic conditions (anaerobic micro-organism are completely depends in glycolysis for energy)
Where does glycolysis take place?
In the cytosol
What happens in the first 5 reactions of glycolysis?
Using an ATP molecule to activate glucose by phosphorylating it
What happens in the last 5 reactions?
Seeing the net generation of ATP
What is ATP used as in Step 1: Phosphorylation of Glucose?
ATP is used as cofactor that acts as a carrier/donor of phosphate groups to phosphorylate many types of molecules.
What happens in Step 1 of Glycolysis?
ATP is used to turn glucose into glucose-6-phosphate
What enzyme helps ATP in this phosphorylation?
Hexokinase
What is a Isozyme?
Two or more enzymes that catalyze the same reaction but are encoded by different genes
How many isozymes of Hexokinase?
4
How does hexokinase 4 differ?
In its kinetic and regulatory properties
What happens in step two of glycolysis?
Phosphohexose Isomeration occurs
What is a Phosphoisomerisation?
Turning Glucose-6-Phsophate into Frutcose-6-Phosphate
What enzyme catalyzes this phosphoisomerisation?
Phosphohexose Isomerase
What is the third step of glycolysis?
The second phosphorylation
What happens in the second phosphorylation?
Fructose 6-phosphate turns into Fructose 1,6-bsiphosphate
What is the enzyme that catalyzes this reaction?
phosphofructokinase-1
What is a Bisphosphate?
Has the phosphate in two different positions
What is a diphosphate?
The phosphates are connected to each other
What is the Fourth Step of Glycolysis?
The Fructose 1,6 bisphosphate splits into two three carbon units
What are the two three carbon units?
Dihydrooxyacetone Phosphate and Glyceraldehyde 3 phosphate
What is the enzyme that catalyzes this reaction?
Aldolase
What happens in the fifth step of Glycolysis?
Interconversions of the triode phosphates (three carbon units)
What does the Interconversion of the Triose phosphates do?
Dihydrooxyacetone Phosphate is immediately isomerized into Glyceraldehyde 3-Phosphate
What enzyme carries out the reaction of the Interconversion of the Triose phosphates?
Triose Phosphate Isomerase
Where does glycolysis continue from?
G3P only
From this point onwards, what must happen?
Two triose molecules must be catabolized for each molecule of glucose with which we started
What is step 5 of glycolysis?
Glyceraldehyde 3-Phosphate Dehydrogenase Reaction
What happens in the dehydrogenase of G3P?
G3P combines with an inorganic phosphate to produce 1,3-biphosphoglycerate
What is the enzyme that carries out this reaction?
Glyceraldehyde-3-phosphate dehydrogenase
What is the cofactor that carries out this reaction?
The reduced cofactor of NAD to NADH
Why is this step the key to glycolysis?
As the 1,3-biphosphoglycerate is a high energy molecule
What must happen to the NADH?
It must be reoxidized to carry out glycolysis as an ongoing process
What is the sixth step of glycolysis?
Phosphoryl transfer from 1,3-BPG to ADP - The first substrate level phosphorylation
What does 1,3BPG turn into?
3-Phosphoglycerate
What reaction occurs for this process?
The conversion of ADP To ATP and the enzyme phosphoglycerate kinase
What is the free energy of the anhydride bond that was broken recovered in?
The form of ATP
What is the overall stoichiometry of this reaction?
Two moles of 1,3-BPG per mole of glucose - so this reaction generates two ATP per glucose
What is the 8th step of glycolysis?
Conversion of 3-phsophoglycerate to 2-phosphoglycerate with the use of the enzyme phosphoglycerate mutaste
What is a mutate?
A sub class of isomerase: mutates catalyze reactions in which a functional group is shunted between different positions in a molecule
What is the 9th step of glycolysis?
Dehydration of 2-phosphoglycerate
What does 2-phosphoglycerate turn into?
Phosphoenolpyruvate with the removal of water
What enzyme does this?
Enolase
What is the 10th step of glycolysis?
Transfer of the phosphorylation group from the phosphoenolpyruvate to ADP: The Second Level Substrate Level Phosphorylation
What does Phosphoenolpyruvate turn into?
Pyruvate (enrol form) with the use of ADP to ATP and the cofactors Mg and K
What enzyme catalyses this reaction?
Pyruvate Kinase
What happens to the Pyruvate (enrol form)
It quickly tautomerizes to keto-pyruvate (giving rise to a large negative delta G)
