Principles Flashcards
How does glucose enter cells?
Via the sodium glucose symporters
What does hexokinase do to glucose?
Turns it to glucose 6-phosphate
What does phosphofructokinase do to fructo 6-phosphate?
Turns it to fructo 1,6-biphosphate
Pyruvate kinase is needed to make what?
Pyruvate
The three enzymes controlling irreversible pathways in glycolysis
Hexokinase, phosphofructokinase, pyruvate kinase
What is derived from niacin?
NAD+
What is regenerated through the metabolism of pyruvate?
NAD+
Where are the enzymes of the TCA cycle located?
The mitochondrial matrix, except succinate dehydrogenase which is located in the inner membrane
How many NADH + H+ and FADH2 produced in each turn of the TCA cycle?
3 NADH + H+ and 1 FADH2
What can pyruvate be converted to?
Alcohol, lactate, acetyl coA
alcohol dehydrogenase, lactate dehydrogenase
What catalyses the oxidative phosphorylation of pyruvate to acetyl coA?
Pyruvate dehydrogenase complex
3 enzymes involved, 2 extra for control and 5 cofactors
What is a major determination of glucose oxidation in well oxygenated tissues?
Pyruvate dehydrogenase complex (this reaction is irreversible lol)
How many high energy electrons in NADH+/FADH2?
2
How can the electron transfer potential be measured?
The redox potential/reduction potential of the compound
How can the phosphoryl transfer potential be measured?
The free energy change for the hydrolysis of ATP
What does a negative E’o mean?
Lower affinity for electrons than hydrogen
What is the standard free energy change proportional to?
The change in standard redox potential and the number of electrons transferred.
What is the change in standard redox potential and number of electrons transferred proportional to?
The change in free energy
How many of the 4 respiratory pumps, pump H+?
3
At which complex does FADH2 enter?
Complx 2 (this is part of the TCA cycle)
What do the respiratory chain proton pumps do?
Pump protons into the intermembrane space
How do protons flow back through from the intermembrane space to the inner matrix?
Through ATP synthase
The importance of the haem group in cytochrome?
Picks up and releases electrons
The glycerol-3-phosphate and malate shuttles are used to do what?
Transport NADH from the cytoplasm into the inner mitochondrial membrane
ATP yield from 1 glucose molecule?
30-32 molecules (depends on exact P/O ration and which shuttle was used)
What is a hydrophobic interaction?
The interaction between a polar substance and a non-polar substance
What is a van der Waals interaction?
Interaction of electrons between non-polar substances
What is acylation?
Addition of an acyl group (RCO)
Electrons are transferred from propane to oxygen to form what?
Water
First law of thermodynamics?
Energy is neither created nor destroyed
Second law of thermodynamics?
When energy is converted from one form to another, some of that energy becomes unavailable to do work
What is a change in enthalpy?
A change in heat content H
What is a change in entropy?
A change in order/randomness S
What are exogernic reactions?
Reactions where the free energy of the products is greater than that of the reactants
These reactions can occur spontaneously
Why is pH 7 included in standard conditions?
Because pH 0/ 1 mol H+ is extremely acidic for the human body
^G values near 0 are characteristic of what?
Readily reversible reactions
Also remember, the closer a reaction is to equilibrium, the more free energy is released
What does phosphoglucomutase do?
Catalyses the reaction of glucose 1-phosphate to glucose 2-phosphate and vice versa
What do you do if the process is unfavourable?
Couple it to a favourable one (i.e one with a negative free energy change. A bit like hi-jacking) This is why ATP is used as a universal energy current
Where will you find high energy anhydride bonds?
ATP
Are reactions with ^G close to 0 used as control points?
No. Reactions with fairly large negative ^G values are used as control points. Flux through these points is controlled by altering the activity of the enzyme involved
What does the acid dissociation (Ka) constant measure?
How readily an acid donates a proton
Buffers and their pKa values?
When buffers are close to their pKa value, they tend to resist a change in pH upon small additions of acid/base
What plots pH as a function of base to acid added?
A titration curve
Zwitterions?
Lol a molecule without charged side groups i.e amino acids (these can be used as buffers)
What is the isoelectric pH?
The pH at which an molecule has no net charge
Why do amino acids have 2 pKa values?
Because they have 2 titratable groups
Which angles can peptides rotate around?
The angle between the C and the carboxyl group
The angle between the C and the amino group
What does proline do to alpha helices?
Breaks them
What does the enzyme which carboxylates proline need?
Vitamin C
What type of protein is collagen?
A fibrous protein
Are globular proteins soluble in water?
Yes, most of their polar side chains are on the outside
Nearly all have masses of alpha helix and beta sheets
Fibrous proteins are not soluble in water
What are involved in sulphide bond formation?
Cysteine molecules (SH)
What contains repeating sequences of X, Y and Gly?
Tropocollagen
Does collagen contain inta-chain H bonds?
No, only inter-chain H bonds
In which condition does a mutation so that valine is produced instead of glutamic acid?
(single nucleotide sequence change)
Sickle cell anemia
valine interacts with other hydrophobic amino acids
What are chaperone proteins?
Proteins which aid protein folding
How do thiol agents (reducing agents) disrupt protein structure?
Reduce and therefore disrupt disulphide bonds
ATP, citrate and H+ are negative modulators of what?
Phosphofructokinase
AMP and fructose 2,6-biphosphate are positive modulators
Adenylate kinase?
2ADP->ATP + AMP
What is the ‘energy charge’?
ATP/AMP ratio
Succinate and FAD produce..?
Fumarate and FADH2
