Summary Biochemistry Metabolism, Biomedical Science year 1 III.

Biochemistry metabolism
Lecture 1
1.0 ENERGY
1.1 What is metabolism?
 Metabolism is a network of interacting chemical reactions that provide cells with Gibbs
energy and building blocks (stofwisseling)

1.2 What diseases can be associated with metabolism
 Metabolic disorders:
 dietary intolerance (lactose, galactose, etc.) • mitochondrial, glycogen deficiencies
 Diabetes and obesity
 Atherosclerosis and cardiovascular disease
 Cancer (proliferation = growth = metabolism)
 Neurological processes (energy, neurotransmitters) • Immunological processes (energy,
proliferation)
 Thus, lots.

1.3 The development of an egg to a chicken: give the dG, dH and dS for
the condition.
 dG < 0 , because..
 dH < 0 , because..
 dS < 0 , because..

1.4 What is coupling ? What type of role do enzymes play in coupling?
 Energy coupling occurs when the energy produced by one reaction or system is used to drive
another reaction or system.
 Endergonic: Describing a reaction that absorbs (heat) energy from its environment.
 Exergonic: Describing a reaction that releases energy (heat) into its environment.
 Through coupling via enzymes, exergonic (DG<0) processes can drive endergonic (DG>0)
processes -> ex. Glucose transport by brush border cell in intestine (Na+ takes up a glucose
molecule and goes into the cell -> L7, what kind? Secondary active transport)

1.5 Why is ATP a source of Gibbs energy?
 Formation of the phosphoanhydride bonds has a positive ∆G: work has to be done to make
the bond, and when the bond is broken energy is released that can be used to do work.
 The function of ATP relies on releasing a phosphate group, and thus releasing energy to do
work. -> Gibbs energy!

1.6 What other sources of Gibbs energy does a cell have?
 Concentration gradients
 Charges over membranes (membrane potential)
 Chemical compounds (not being ATP: XTP, phosphocreatine, PEP)
 Reduction – oxidation power (similar to those that power batteries)
 Light (photons)

,1.7 Fill in the pathway of the dietary components:




1.8 What happens at the basal state (overnight fast)?
Stores mobilized:
 Glycogen for glucose
 Protein for glucose
 Fat for oxidation
 Insulin low, glucagon rising

1.9 What happens at a starvation state?
Stores mobilized:
 Glycogen depleted
 Protein for glucose
 Fat for oxidation
 Switch to ketone bodies
 Insulin low, glucagon high

1.10 Fill the bow tie structure of metabolism in
 Nutrient uptake - core metabolism - peripheral metabolism

, Lecture 2
1.0 CHEMICAL POTENTIAL DIFFERENCE
1.1 Molecules A can freely cross the membrane. What is the net rate of
movement of molecules?




 0

1.2 What does it depend on?
 Concentration gradient

1.3 When is the net movement zero?
 When the number of molecules going out of the membrane is equal to the number of
molecules moving into the membrane.

1.4 How would you define the force that moves the molecular flow?
 Chemical potential difference

1.5 What is a chemical potential difference?
 The force that make chemicals flow or react (the average of molecules, not individual
molecules!). Chemical potential depends on (the natural logarithm of) concentrations
 the Gibbs energy difference per mol molecules

1.6 If each spontaneous process requires that dG <0, then when does that
process stop?
 When equilibrium is reached. S = 0, thus dG = 0

1.7 What are the rules for natural logarithms?
 ln(1) = 0
 ln(xa) = a ln(x)
 ln(1/x) = ln(x-1) = -ln(x)
 ln(a) + ln(b) = ln (a⋅b)
 ln(a) - ln(b) = ln (a/b)

1.8 What is the formula for the chemical potential ?
 μA =μA0’ +RTln[A] A =μA =μA0’ +RTln[A] A0’ +RTln[A]
R: gas constant = 8.31 J K-1 mol-1
T: absolute temperature K
μA =μA0’ +RTln[A] A0’ : chemical potential at standard conditions (1 M, 298 K, pH 7)