Explain how a metabolic pathway can contain an energetically unfavorable reaction
yet still occur.
The free-energy changes of the individual steps in a pathway are summed to determine
the net free-energy change. Thus, a step that might normally occur c
1. 1-phosphofrucktokinase catalyzes the first committed step in the glycolysis, i.e. the
transfer of phosphoryl group from ATP to fructose-6-phosphate to yield fructose-1, 6bisphosphate. This step is regarded as the rate limiting step of glycolytic pathwa
Gluconeogenesis and glycolysis both the cycle occurs mainly in the cytosol.
Gluconeogenesis produces glucose and glucose is catabolised in glycolysis to form
pyruvate, therefore, within a cell both the cycles must be regulated reciprocally. AMP
1. Describe the relationship between fatty acid chain length, saturation, and the melting
point or fluidity of fatty acids.
As the number of carbon atoms in the chain or simply the chain length increases, the
melting point also increases. This is why long
You believe a substrate fits into a cleft like a key into a lock, but your roommate
does not. Who is right?
There are two theories concerning enzyme activity and enzyme binding with substrates. First
theory is the lock and key model. Only specific key
Why are membranes impermeable to most substances?
Most substances are not permitted to cross the membranes because they are composed of a
lipid bilayer. It do not allow large molecules, polar molecules and charged ions to cross this
barrier. Smaller mo
1. How is water able to be a solvent for so many biological molecules?
Water being polar is able to be a solvent for many biological molecules. The oxygen in the
water molecule, which is covalently bonded to two hydrogen atoms, is more electronegative
Question 1: The reaction for the cleavage of fructose 1,6-bisphosphate to dihydroxyacetone
phosphate and glyceraldehyde 3-phosphate is catalyzed by the enzyme fructose 1,6bisphosphate aldolase and has a standard free energy change of G = +23.8 kJ/mol.
The Electron Transport Chain (ETC)
ATP synthesis is not an energetically favorable reaction, therefore, energy is needed in order
for it to occur. This energy is derived from the oxidation of NADH and FADH 2 by the four
protein complexes of the electron t
Pyruvate dehydrogenase complex:
The pyruvate dehydrogenase complex links glycolysis to the Krebs cycle. It is a multi-enzyme complex
consisting three enzymes involving five cofactors. Function of the enzyme is to oxidize pyruvate to
M7 Discussion: What Makes a Pathway - Gluconeogenesis
Pathway Summary: Gluconeogenesis is a pathway that is used to synthesize
glucose (from non-carb precursors like lactate, glycerol and amino acids) in times
of starvation or fasting that uses the substr
Mitchells Chemiosmotic Theory
Peter Mitchell proposed three hypotheses which he unified into Chemiosmotic theory to
explain the mechanism of oxidative phosphorylation in mitochondria (and
photophosphorylation in chloroplasts). According to this hypothesis