Cori and Krebs Flashcards
Give a summary of glycolysis. So name each enzyme used for the 10 steps
1) Hexokinase HexoK
2) Phospho Isomerase
3) PFK1
4) Aldolase
5) TPI
6) GAPDH
7) PGK
8) PGM
9) Enolase
10) PK
What are the 5 major fates of Pyruvate?
1) Ethanol
2) Lactate
3) Acetyl CoA
4) Oxalacetate
5) Alalanine
What are the 2 fates of pyruvate made in the mitochondrial matrix?
Oxaloacetate and Acetyl CoA
What process gives ethanol from pyruvate?
Fermentation
Name the following things for fermentation of pyruvate
1) how many steps?
2) describe each step
3) enzymes used for each step
4) the extras needed for each step
5) any byproducts?
6) reversible or irreversible?
1) 2 step process
2) first step is pyruvate to acetaldehyde
2nd step is acetaldehyde to ethanol
3) pyruvate decaroxylase for first step
alcohol dehydrogenase for second step
4) TPP and Mg2+ for first step
NADH + H+ for second step
5) CO2 first step. NAD+ formed for 2nd step
6) both reversible
How is lactate formed?
1) Name the enzyme used
2) Name the conditions needed
3) what important role does the enzyme play?
4) high amounts of what can produce what?
L- Lactate is formed from pyruvate during anaerobic glycolysis
1) Lactate dehydrogenase
2) Anaerobic
3) Regenerates NAD+ for step 6 of glycolysis
4) High amounts of lactic acid can produce acidosis
what is the cori cycle?
metabolic pathway in which lactate produced from pyruvate in the muscles is transferred to the liver where it is then converted to glucose. This glucose is then transferred back to the muslces and stored as glycogen and the cycle is repeated
What role does ATP play in the muscle and in the liver during the cori cycle.
In the muscle, the production of atp when glycogen is converted to lactate is used for rapid contraction of the muscle.
In the liver, ATP is used in the synthesis of Glycogen from lactate during recovery. (GNG)
Descirbe the structure of gylcogen and describe the bonds and branching
Polysaccharide
alpha-D-glucose units linked via alpha1 ->4 glycosidic bonds with alpha1->6 branch points
Glycogen is the storage form of what in the body?
Storage form of carbohydrate in the body
Why is glycogen critical during fasting?
Liver glycogen provides a source of blood glucose
What type of glycogen cannot give rise to blood glucose?
Muscle glycogen
Glycogenolysis is what?
Breakdown of glycogen and involves
1) Glycogen phosphorylase
2) Debranching enzyme
3) Phoshoglucomutase
Glycogensis is what?
Synthesis of glycogen and involves
1) UDP glucose pyrophosphorylase
2) Glycogen synthase
3) Amylo 1->4 to 1->6 transglycosylase (glycogen branching enzyme)
Describe how glycogen phosphorylase works and what it needs
It needs an inorganic phosphate.
It works by shortening the glycogen by one residue and adding phosphate onto that residue.
So produces glucose1phosphate and the rest of the glucose residue
How does the debranching enzyme work and what type of activity does it have?
What is the result?
It has bifunctional activity
1) Transfers a block of 3 glucose residues to a nearby nonreducing end
2) hydrolyses the alpha1->6 linkage to release a free glucose
Results in an unbranched alpha1->4 polymer susbtrate
Phoshoglucomutase does what and how? is this step reversible or irreversible
Transfers a phosphoryl group on Glucose1Phosphate from C-1 to C-6.
Forms Glucose 6 Phosphate. Reversible
Glucose1Phosphate is made into Glucose1,6Biphosphate then turned into Glucose 6 phosphate
UDP Glucose Pyrdophosphorylase does what? and what does it also produce
Synthesises UDP Glucose from UTP and Glucose 1 Phosphate and also produces pyrophosphate (PPi). PPi can be broken into 2 Pi’s
Glycogen synthase works how?
Takes UDP glucose and a nonreducing end of a glycogen chain with n (n>4) residues and joins it together to produce Elongated glycogen with n+1 residue and UDP as a byproduct.
How does glycogen branching enzyme work?
Catalyses the transfer of a block of 6 or 7 glucose residues from the nonreducing end of a glycogen branch having at least 11 residues to the C6 Hydroxyl group of a glucose reside in a more interior position within the same or a different glycogen chain.
What can glycogen synthase not do? so what does it require?
Cannot initiate synthesis of a new glycogen chain since it requires a primer usually pre-formed (1->4) polyglucose chain
What does glycogenin do?
The primer on which new glycogen chains are synthesises and the enzyme that catalyses their assembly
PDH Complex
1) the full name
2) is involved in what reaction?
3) made up of how many enzymes?
4) how is it related to the citric acid cycle?
5) catalyses how many steps and uses how many cofactors?
6) name the cofactors
1) pyruvate dehydrogenase complex
2) Pyruvate to AcetylCoA
3) 3 enzymes, E1, E2, E3
4) First control point of the cycle
5) Catalyses 4 steps, 5 cofactors
6) Co-A, NAD+, TPP, Lipoate, FAD
What are the 8 vitamin Bs?
Thiamine, Riboflavin, Niacin, Pyridoxine, Pantothenic acid, Biotin, Folic acid, Cobalamine
Thiamine is needed for what?
TPP in PDH
Riboflavin is needed for what?
FAD and FMN
Niacin is needed for?
NADH and NADPH
Pyridoxine is needed for?
PLP
Pantothenic acid is needed for?
Coenzyme A
Biotin is needed for?
Pyruvate Carboxylase
How many reactions in the krebs cycle?
8, but tech 9
