Part A:
Monomers of proteins : aminoacids
An amino acid is an organic acids containing an amine group.. Such organic compounds therefore have both a carboxyl group -COOH and an amine group, for example a primary amine -NH 2 or a secondary amine -NH-. In the living world, about 500 amino acids are known, of which about 149 are present in proteins.
In biochemistry, α-amino acids play a crucial role in the structure, metabolism and physiology of cells of all known living organisms as constituents of peptides and proteins.
Monomers of nucleic acids: nucleotides.
A nucleotide is an organic molecule that is the building block of a nucleic acid such as DNA or RNA. It is composed of a nucleic base (or nitrogenous base), a five-carbon monosaccharide, called the pentose, whose association forms a nucleoside, and finally one to three phosphate groups.
A nucleotide is composed of three parts:
* A nucleotide variable depending on the type of nucleotide (purine or pyrimidine) attached to the carbon 1 'of deoxyribose;
* a sugar with five carbon atoms;
a phosphate group (or phosphoric acid), identical for the nucleotides of DNA and RNA, attached to the 5 'carbon atom of the deoxyribose, and to the 3' carbon atom of the nucleotide deoxyribose following).
Since phosphates and sugars are always the same in a given nucleic acid, the nature of the nucleotide is determined by the nucleic base it contains. The sequence of a strand of DNA or RNA can therefore be summarized in the succession of nucleic bases present. The five main nucleotides are named according to their nucleic base.
Part B:
Role of DNA and his relation with proteins:
A protein is an assembly of amino acids.
The DNA is contained in the chromosomes and formed of nucleotides (nitrogenous base, phosphate and deoxyribose which is a sugar).
These two entities are linked by a very important but implicit link. We will discover it little by little.
Chromosomes consist of DNA.
DNA is a molecule called deoxyribonucleic acid. The DNA is in the nucleus while the proteins are in the cytoplasm of the cell.
DNA contains genes, since it constitutes chromosomes. The role of genes is to make proteins so that they can act in cells. It must be taken into consideration that there are several types of proteins. It should be known that DNA can not act alone to renew the "stock" of proteins of the cell.
There is an intermediate nucleic acid between DNA and the proteins that is RNA.
This intermediate could be a particular molecule: RNA. Indeed, during the synthesis of a protein in the cytoplasm, the ribosomes (organelles where the protein synthesis takes place) are aligned along an RNA molecule.
Take the image of DNA as a computer. This computer contains files, unreadable data, here the genetic information, that takes a USB key (the messenger RNA). This done, this key comes out of the nucleus through the pores of the nuclear envelope and gives its data and files taken from a machine, which symbolizes the ribosome, which will organize the information received to create many different objects, proteins, according to the information it receives, being itself a protein.
Role of the protein in the cell.
In the body, proteins play essential roles:
*They play a structural role and participate in the renewal of muscle tissue, integuments (hair, nails, hair), bone matrix, skin, etc.
*They participate in many physiological processes, for example in the form of digestive enzymes, hemoglobin, hormones, receptors or immunoglobulins (antibodies).
They are, moreover, the only source of nitrogen in the body.
