Cell Metabolism Flashcards
What is the difference in Phosphodiester bonds and Phosphoanhydride bonds?
A bond between a sugar group and a phosphate group
The high energy of this molecule comes from the two high-energy phosphate bonds. The bonds between phosphate molecules are called phosphoanhydride bonds. They are energy-rich and contain a ΔG of -30.5 kJ/mol.
How many molecules of ATP are formed per molecule of glucose?
36-38 molecules.
38 * -31 = 1178 kJ/mol
1178 / 2872 ( combustion of glucose ) =
41% efficient
What reaction is defined by formation of covalent bonds?
Ligation requiring ATP cleavage
What type of reaction is glucose to glucose 6 phosphate?
Phosphate group transfer (phosphorylation)
Hexokinase required
irreversible reaction
traps glucose by means of negative charge
What reaction does Phosphoglucose isomerase aid?
Glucose 6 phosphate to fructose 6 phosphate
isomerization
Why does phosphofructokinase need to be regulated?
Fructose 1,6 biphosphate is created which is entered into the glycolysis pathway.
Group transfer reaction
What hydrolytic reaction does the enzyme aldolase aid?
Fructose 1,6 biphosphate to G3P ( glyceraldehyde 3 phosphate) and DHAP (Dihydroxyacetone phosphate)
Both high energy compounds
hydrolytic reaction
What does TPI stand for and what reaction does it affect?
It is the enzyme: Triose phosphate isomerase.
Dihydroxyacetone phosphate to glyceraldehyde 3 phosphate
isomerisation reaction
what deficiency is the most severe form of a group of diseases known as glycolytic enzymopathies, which are rare genetic diseases that lead to the degeneration of the red blood cells.
Triosephosphate isomerase deficiency. most sufferers die within the first 6 years of their lives
When is NADH first generated in glycolysis?
2 are formed when 2 G3Ps made into 1,3 biphosphate by G3P dehydrogenase
Redox and group transfer
What does 1,3 biphosphate become and what enzyme is involved?
3-phosphoglycerate ( 3PG)
3-phosphoglycerate kinase ( creates 1 ATP)
group transfer
What does 3 phosphaglycerate become and what enzyme is involved?
2-phosphoglycerate
phosphoglycerate mutase
isomerisation reaction
What reaction is enolase involved in and why is it a dehydration/group removal reaction?
2-phosphoglycerate to phosphoenolpyruvate + H2O (removed)
also a group removal
How is pyruvate created at the end of glycolysis?
Phosphoenolpyruvate to pyruvate through a group transfer reaction.
By pyruvate kinase, generates ATP
group transfer
What are the net results of glycolysis?
2 NADHs
2 ATPs ( 4 ATP - 2 ATP)
2 pyruvates
What uses the Alcoholic fermentation of pyruvate?
Yeast and can occur under anaerobic conditions
How is Pyruvate turned into Ethanol through alcoholic fermentation?
Pyruvate is turned to Acetylaldehyde through pyruvate decarboxylase
Acetylaldehyde is reduced into Ethanol by alcohol dehydrogenase and NADH oxidation to NAD
How is lactate generated by Pyruvate and why?
By lactate dehydrogenase and NADH oxidised to NAD+. It is a reversible reaction
Cells will produce lactate to replenish NAD+
Why is NAD+ needed?
for the dehydrogenation of G3P which is the first step pf generating ATP for the body, it may become reduced as NADH formation is greater than oxidation occuring by oxidative chain for NAD
What role does Creatine phosphate play?
Acts as a buffer
Can be broken down into Creatine and ATP when phosphate is in high demand.
How is Pyruvate turned into Acetyl CoA and CO2?
Pyruvate reacts with HS-CoA through pyruvate dehydrogenase (PDH) and NAD reduction.
(ligation reaction)
occurs in mitochondria of cell
What is the high Energy bond in Acetyl CoA and why is it important?
Thioester bond
Readily hydrolysed enabling Acetyl CoA to donate the Acetate ( 2 carbons ) to other molecules.
How can a Vitamin B12 deficiency lead to a Beri Beri?
VB12 creates Thiamine which acts as a cofactor for PDH. A deficiency causes damage to peripheral nervous system, musculature weakness and decreased cardiac output.
Thiamine pyrophosphate is a cofactor of PDH complex - readily loses proton and results in carbanion attacking pyruvate
Why is the brain vulnerable in Beri Beri?
It relies heavily on glucose metabolism, Need to break down pyruvate to Acetyl CoA which is compromised in Beri Beri
What is oxidation-reduction reaction?
Electron transfer
ATP hydrolysis during exercise?
ATP stores decrease creatine phosphate increases - all happen in 4 seconds
Anaerobic metabolism starts slowly and before aerobic metabolism which eventually overtakes it
hence why creatine used as a dietary supplement