Nucleic acids are composed of monosaccharides connected by phosphoester liaisons and wearing a base. One monosaccharide and its base are called one nucleoside. One monosaccharide, its base and one phosphate are called a nucleotide. RNA and DNA are composed of one similar monosaccharide, the ribofuranose, with the difference that the 2’ has an H on […]
Author: Dr GERARD Thomas
Chapter 5 : 3D structure of proteins
The structure of the protein is obtained during the formation of the protein. The structure of the protein is necessary for its function: some active sites are present on the proteins. Those sites are highly specific to one target substrate. Other substrates cannot reach the active site. The rest of the molecule is mostly there […]
Chapter 4 : Primary structure of proteins
The primary structure of a protein is the succession, or sequence, of the AA. Proteins are made of one linear chain of amino acids. This linear chain takes a 3D structure (secondary and tertiary structures) because of the interactions between the sequences in the chain and the interactions (hydrophobic or hydrophilic) with the surrounding. The […]
Chapter 3 : Proteins and amino acids
The word protein comes from the Greek word proteos, which means first. Proteins are indeed one essential element of the life. They are well defined in composition, size and shape and each one has a very precise role: transport, defence, hormones, … Some have also an exotic role. For instance some proteins prevent the blood […]
Chapter 2 : Glucides
Glucides are essentially cyclic hydrates of carbon (CN(H2O)N) but can also wear N, S, P. The cycles are usually 5 or 6 atoms long and form macromolecules when cycles bind together. One example is the cellulose, which is the walls of vegetables. As humans, we don’t properly digest the cellulose contained in the salads we eat […]
Chapter 1: Biochemistry – Introduction and lipids
Biochemistry is a field of the chemistry related to the living bodies, animal or vegetal. This field is far from the inorganic chemistry and a simple comparison can show it: the repartition of the molecules in the earth’s crust and in a living body are totally different. The first is essentially composed of silica and […]
Chapter 15 : MPC – Molecular degrees of freedom: vibration and rotation
In the Born-Oppenheimer approximation, we froze the position of the nuclei to find the electronic energy. The position of the nuclei was considered as a parameter that can be modified and we were able to construct the Lenard-Jones potential for the liaisons or the surface (or hypersurface) of potential energy for molecules with more than […]
Chapter 14 : MPC – The LCAO theory
This theory says that each molecular orbital Φa is described by a linear combination of atomic orbitals {χ} centred on the M nuclei of the molecule. The molecular orbitals have the symmetry of one of the irreducible representations of the group G. This symmetry is taken into account in the LCAO coefficients. Some are null […]
Chapter 13 : MPC – The methods of approximation and the quantic chemistry
We have seen quite a lot of new stuff up to now. We described monoelectronic and polyelectronic atoms and developed the description to molecules through the approximation of Born-Oppenheimer, the theory of groups and the CSOC. All of this teaches us how orbitals are and how they change during a reaction. Yet, we did not […]
Chapter 12 : MPC – Orbital angular moment L
The electrons revolving on an orbital generate an angular moment. ML is the quantic number associated to the projection of L on the internuclear axis. The projection is degenerated because it can either be in the positive values of the z axis or in the negative ones. The projection of L can thus give ML […]