Institute of Robotics and Intelligent Systems Department of Mechanical and Process Engineering (DMAVT) ETH Zurich
NANOROBOTICS 2015 Exercise Session 5 Solutions Assistants: Berna Özkale ([email protected])
Marcus Hoop ([email protected]) Dr. Salvador Pané Prof. Dr. Bradley J. Nelson
Experimental Setup
2
Kinesin molecules are attached on a glass surface and function as a molecular motor to promote directional motion of Microtubules. The Microtubules act as a cargo system for attached liposomes (diameter 50nm), which are prepared in an aqueous solution composed of Rhodamine B (chemical dye molecule) and phospholipids. The average velocity of the Microtubules is given in the diagram below.
Distan
ce travelled (um)
(Hess et. al, Molecular Biotechnology, 2001)
Question 1
Assume that a microtubule moves along a kinesin coated pathway of 1 mm (max. velocity). How much molecules of ATP will be used by the kinesin motors during that motion? How much energy (kJ) will be used, assuming that the hydrolysis of ATP produces 30.5 kJ/mol? Avogadro constant = 6.022 * 1023 mol-1
3
1000!"0.7!" ∗ 0.5 ∗ 10!!!"# ∗ 6.022 ∗ 10!"!"#!! = 4.3 ∗ 10!!!!"#$%&#$'!!"!!"#
1000!"0.7!" ∗ 0.5 ∗ 10!!!"# ∗ 30.5 !"
!"# = 21.79!!"
Question 2
4
Briefly explain the underlying principal of liposome formation with the phospholipid shown above.
Hydrophilic Head
Hydrophobic Tail
Phospholipid properties: • Hydrophilic head • Hydrophobic tail Phospholipids in aqueous solution: • Hydrophobic tails will come together and form a lipid
bilayer by excluding the water from the interface • Lipid bilayers are unstable since hydrophobic edges
are still in contact with water • Multiple bilayer will interact with each other, forming a
spherical structure with no hydrophobic tails exposed to water molecules (=Liposome).
Question 3
5
Assume that 106 liposomes were formed in an aqueous solution containing 500 mM Rhodamine B (Molecular Weight = 479 g/mol). How much Rhodamine B will be loaded in the liposomes?
! = 4!!!3 = 65449.85!!"! = 6.54 ∗ 10!!"l!
! ∗ 500!!!"#! = 3.27 ∗ 10!!"!"# ∗ 479 !!"# = 1.56 ∗ 10!!"! ∗ 10! = 15.6!!"!
Question 4
6
Name the class and explain the difference between the isomers shown below. Which structure is more stable? Justify your answer. Trans Cis
! Stereoisomers in cis and trans state ! The molecule in the trans state is more stable, due to increased steric
hindrance in the cis molecule caused by the Cl atoms in close proximity
