Cell metabolism Flashcards
What are the 6 types of reactions?
Oxidation-reduction, Ligation requiring ATP cleavage, Isomerization, Group transfer, Hydrolytic, Addition or removal of functional groups.
What is oxidation-reduction?
Electron transfer.
What is ligation?
Formation of covalent bonds.
What is isomerization?
Rearrangement of atoms.
What is group transfer?
Transfer of a functional group from one molecule to another.
What is hydrolytic?
Cleavage of bonds by the addition of water.
What is addition or removal of functional groups?
Addition of functional group to double bond or removal of functional group to form double bond.
What are the two phases of glycolysis?
Energy consuming phase and energy producing phase.
What is a kinase?
An enzyme that catalyses the transfer of a phosphate group from one molecule to another.
Why can’t glucose-6-phosphate diffuse out of cell?
Cause of the negative phosphate group. Makes molecule more reactive and can’t bind to glucose carriers.
What key enzyme regulates entry of sugars into glycolysis pathway?
Phosphofructokinase.
Deficiency in what glycolytic enzyme is fatal?
Triose phosphate isomerase.
What is an isomerase?
An enzyme that catalyses the rearrangement of bonds within a single molecule.
What is a dehydrogenase enzyme?
An enzyme that catalyses the oxidation of a molecule by removing a hydride ion.
What is a mutase enzyme?
Catalyses the shift of a chemical group from one position to another within a molecule.
Why is glycolysis described as substrate level phosphorylation?
Phosphate group is directly being transferred from a substrate (sugar intermediate) to ADP.
What is fermentation?
Breakdown of sugar in absence of oxygen.
Why is pyruvate converted to lactate? What enzyme converts it?
Allows continuation of glycolysis as NAD+ is regenerated by converting pyruvate into lactate and oxidising NADH to produce NAD+. Lactate dehydrogenase.
Where is NAD+ needed in glycolysis?
Dehydrogenation of glyceraldehyde 3-phosphate into 1,3-bisphosphoglycerate.
Which is the high energy intermediates in glycolysis?
1,3-bisphosphoglycerate and phosphoenolpyruvate.
Why are molecules called high energy intermediates?
Hydrolysis of phosphate bond has high delta G. Very energetically favourable.
How is pyruvate converted to acetyl CoA?
Decarboxylation. Addition of co enzyme A. NADH produced.
What catalyses pyruvate to acetyl CoA?
pyruvate dehydrogenase complex
How many carbons is a fatty acid chain shortened by to produce a molecule of acetyl CoA?
2 carbons.
Where are fatty acids converted into acetyl CoA?
Mitochondrial matrix.
What else is produced in the conversion of fatty acids to acetyl CoA?
One molecule of FADH2 and NADH.
Where do the oxygen atoms to make CO2 in the krebs cycle come from?
Hydrolysis of three water molecules.
What does one turn of the krebs cycle produce?
Three NADH molecules, One GTP molecule, one molecule of FADH2 and two molecules of CO2.
What molecules can be formed from the intermediates from glycolysis and citric acid cycle?
Amino acids, lipids, nucleotides and other small organic molecules.
What is produced from glycolysis?
Two molecules of pyruvate, 2 molecules of ATP and 2 molecules of NADH.
What does creatine phosphate do?
Acts as a buffer for demand for phosphate.
Why do people take creatine as a supplement?
To increase creatine phosphate.
What allows acetyl CoA to donate the acetate group?
High energy thioester bond (C-S Bond) so it is readily hydrolysed.
Pyruvate to acetyl CoA products?
Acetyl CoA, NADH and CO2.
3 key glycolysis enzymes?
TPI, PFK and PDH
What biochemical pathway does beri beri affect?
Conversion of pyruvate to Acetyl CoA.
What results in Beri Beri?
Lack of thiamine which results in poor pyruvate dehydrogenase function.
Beri Beri symptoms?
Damage to peripheral nervous system, weakness of musculature and reduced cardiac output.
Why is thiamine required for proper PDH function?
Required for thiamine pyrophosphate which is a cofactor in PDH.
What is transamination?
Amine group is transferred from amino acid to keto acid forming a new pair of amino acid and keto acid.
Why does NADH high energy electrons need to enter the matrix of the mitochondria?
So that they can be used in oxidative phosphorylation and to regenerate NAD+ for glycolysis.
How are electrons from NADH produced in cytoplasm transferred across mitochondrial membrane?
Via a shuttle.
In the glycerol phosphate shuttle what is the final destination for the electrons transferred to?
FAD and then to co-enzyme Q (part of electron transport chain).
Where is the glycerol phosphate shuttle used in the body?
Skeletal muscle and brain
Where is the malate aspartate shuttle used?
Liver, Kidney and heart
What transports malate and aspartate across the mitochondrial membrane?
Antiporter. (As one molecule goes in another molecule leaves).
How many ATP molecules per molecule of NADH?
3
How many ATP molecules per molecule of FADH2?
2
What is the warburg effect?
Mutations in genes of Fumerase, Succinate, Isocitrate Dehydrogenase, decreases Kreb’s Cycle activity which enhances anaerobic glycolysis. Generation of lactate from glucose even in increased O2 availability.
Caloric yield of fats compared to carbs?
Fats have 2x the caloric yield.