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Nobel prizes 2016 in Medicine, Chemistry and Physics

Nobel prizes are awarded annually for outstanding contributions for humanity in chemistry, economics, literature, peace, physics, physiology or medicine. It’s regarded as the most prestigious award in these fields. In this article, we will explore the research that won the Nobel prizes in the field of sciences in 2016.

Nobel prize in physiology or medicine:

In case you guys wonder about what is physiology: Physiology is the study of how organisms and their internal system like organs, cells, biomolecules carry out physical and chemical processes. The 2016 Nobel prize in this category was awarded to Yoshinori Ohsumi for discovering the mechanism of ‘autophagy’. The word autophagy originates from the Greek words ‘auto’ meaning ‘self’, and ‘phagein’, meaning ‘to eat’. Thus, autophagy literally means ‘self eating’.

Let us understand this process by a simple example. Imagine you have food in your freezer. Suddenly something went wrong with it and it stops working. You notice it after some days and by then the food inside is wasted. You throw this waste into a bin. Similar processes occur in a cell when something goes wrong with a cell. A cell destroys its own contents by packing them in sack-like vesicles called ‘autophagosomes’. These autophagosomes then transport these packets to another compartment of cell called ‘lysosomes’. Lysosomes are considered as ‘garbage bins’ of a cell, where the content is degraded. This degradation takes place in presence of some enzymes.

Experiments done by Yoshinori:

Yoshinori used yeast cells to understand the mechanism. He first mutated the cells in such a way that will eliminate the degradation enzymes responsible for degradation in lysosomes. By doing this, the waste will be transported to the lysosomes, but will not be degraded. Then he starved the cells to death! i.e. induced autophagy. The results were amazing. Autophagosomes started accumulating in the lysosomes which could be seen under a microscope and this proved that autophagy occurs in the yeast cells.

The next step was to identify the genes responsible for autophagy. Yoshinori designed another set of experiments where he exposed the yeast cells to some chemicals which will mutate the genes randomly. When a chemical will mutate the genes which were responsible for the autophagy, the process will not occur. Hence by repeating the process several times with different chemicals he was at last able to identify those genes. This was a ground breaking discovery because mutations in autophagy genes can cause diseases, and the autophagic process is involved in several conditions including cancer and neurological diseases.

Nobel prize in Chemistry:

The Nobel Prize in Chemistry 2016 was awarded jointly to Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard L. Feringa ‘for the design and synthesis of molecular machines’.

Machines have been best friends of humans for centuries. But, how small can a manmade machine be? Humans being curious beings have always tried to push limits and achieve something extra ordinary. One of such successful attempts is creating miniature machines made up of few molecules. The first step in creating a machine is to figure out the way to assemble different parts. Sauvage’s team found out a way to link two molecules in a chain by using copper ion. On the top of it, this bond was flexible allowing free movement of molecules about the bond. With the help of this, Stoddart’s group designed a molecular machine called ‘rotaxane’. Potential application of rotaxane is molecular shuttle, which can be used to shuttle molecules from one place to another. They even constructed a molecular elevator using rotaxane which could raise itself 0.7 nm from the surface.

Chemical structure of a nanocar. The wheels are C60 fullerene molecules.
Chemical structure of a nanocar. The wheels are C60 fullerene molecules.

Bernard Feringa produced the first molecular motor in 1999. This ‘nanocar’ is composed of something that can be linked to two small rotor blades, two flat chemical structures that are joined with a double bond between two carbon atoms. A methyl group is attached to each rotor blade; these, and parts of the rotor blade, work like ratchets that force the molecule to keep rotating in the same direction. The car is driven when it was exposed to UV light. Initial research done by Sauvage, Stoddart and Feringa will act as a tool box to construct next generation molecular machines.

Nobel Prize in Physics:

David J. Thouless, F. Duncan M. Haldane and J. Michael Kosterlitz were awarded Nobel prize in Physics for their ‘theoretical discovery of topological phase transitions and topological phases of matter’. Even though I did a one year project on the same topic back in India, this subject is difficult to explain in simple language. I will try my best to simplify.

Topology:

Imagine that you have a lump of clay and you flatten it out into a disk shape. Now you make a bowl from it and after that a glass. Topologically speaking, disk, bowl and a glass are all similar. A cup with a handle and a doughnut are also similar. As far as you can preserve the number of holes in an object when you continuously transform it from one shape to another, the objects are topologically equivalent. Topology is a branch of mathematics dealing with the study of objects which are topologically distinct or similar.

Phase transitions:

Matter around us exits in different phases namely gas, liquid and solid. Consider a simple example of ice. Upon heating, it will change into water and then into water vapours. Here the phase of matter changes twice. First from solid to liquid and then liquid to gas. The change of phase in any sort of matter is known as phase transition. These phases depend on how strongly the atoms are bound to each other.

Crystal structure of rotaxane with a cyclobis(paraquat-p-phenylene) macrocycle
An example of a molecular shuttle where the macrocyle (green) moves between two stations (yellow).
Crystal structure of rotaxane with a cyclobis(paraquat-p-phenylene) macrocycle
Crystal structure of rotaxane with a cyclobis(paraquat-p-phenylene) macrocycle.

Topological phase and topological phase transitions:

When we go from three dimensions to two or even one dimension, the properties of matter change drastically. Conventional quantum physics was not able to explain those phenomena. Topological phase is totally different form usual solid, liquid or gas phase. When we cool down the gas to almost absolute zero temperature such that its only confined to two dimensions, the atoms form tight vortex pairs. Vortex is something you see very commonly e.g. when water goes down the sink it whirls around the outlet. But in topological phase, the vortex pairs wander around together. When we start increasing temperature, at some point, these vortexes break-up and start wandering freely. This is known as topological phase transition and was discovered by Kosterlitz and Thauless. These transitions are also known as Kosterlitz-Thauless transitions. When we vary the magnetic field applied to this two-dimensional matter, the electrical conductance also changes, but only in integral steps i.e. twice, thrice and so on. This gradual integral change in conductance couldn’t be explained by the present physics but then David Thauless found out the solution in topology, as the no. of holes in topological object are also integral. Haldane studied one-dimensional matter using topology as well.