Lecture 2

The biochemical basis of lifeis composed of:

1 -Organic compounds

2 -Inorganic compounds

1 -Organic compounds

Organic compounds include: carbohydrates, proteins, fats, vitamins, nucleic acids and hormones.

All share in containing carbon element associated with oxygen and hydrogen .

The function of carbohydrates lies in being the first source of energy in the cell.

Carbohydrates are classified into the following

sections:

-Monosaccharides:Is one of the simplest kinds of sugars which consists of a certain number of carbon atoms ranging from three to six. Three carbon atoms as Dihydroxyacetone, Five as ribose, Six as hexose (glucose)monosaccharides having this molecular formula (C6H12O6)

-Disaccharides-:They produced from the Union of the two parts ofmonosaccharides accompanied by loss of a water molecule including sucrose, all bearing the molecular formula C12H22O5

-Polysaccharides-: Produced by the process of gathering monosaccharides called polymerization process after the loss of water molecule, there are 2 forms:chains such as cellulose and branched asstarch, and bear the molecular formula C6H10O5.

Fat consists of three basic elements are carbon, hydrogen and oxygen in addition to the element phosphorus.

These elements combine together to be the so-called fatty acids which are of general formula R-COO. There is unsaturated fat such as liquid vegetable oils and saturated fat such as solid fat (butter).

1-2 Lipids

Fatty acids combine with alcohol to give lipid of which its quality depends on the number of carbon and hydrogen atoms. There is unsaturated fat such as liquid vegetable oils and saturated fat such as solid fat.

The unsaturated fat can be transferred to the saturated one by hydrogenation (addition of hydrogen).

1-3 Proteins:The protein is composed of four basic elements (C,N,H,O) . In addition to other secondary elements as P, S, Fe.

the resulting combination of these elements together is so-called amino acids which are the basic units of composition and function in proteins.

Amino acids are bearing this formula: H2N-CH-COOH R

In Nature, there are 20 amino acids, divided in terms of their importance into two division basic amino acids (8) such as : Leucine , IsoLeucine, Lycine , Methionine , Treptophaan, Phenylalanine, Therionine, Treptophan, Valine.

And non-essential amino acids (12) such as Glycine, Cysteine , Arginine , Proline …….etc.

1 -4 Nucleic acidsThere are in nature two types of nucleic acids:1- (DNA) Deoxyribonucleic acid2- (RNA) Ribonucleic acid.

DNA is composed of deoxyribose sugar, phosphate group and nitrogenous (A, G, C, T) RNA is composed of ribose sugar, phosphate group and nitrogenous base (A, G, C, U).

DNA consists of double helix while the RNA consists of a single strand. Thus the (DNA) molecule has higher molecular weight than RNA.

1 -5 VitaminsVitamins are classified with the secondary nutrients which does not possess energy and is not manufactured in the body. They affect the metabolism of food and help protect the body from certain diseases.

2 -Inorganic compounds:It includes water and chemical elements as oxygen, hydrogen, nitrogen and carbon.

Water constitutes the bulk part of the bodies of living organisms.

proportion of water in the human body is between 20% in the bone to 85% in the cells of the brain.

The chemical element is defined as the material that can not be analyzed into simpler substance by chemical reaction. The universe contains 92 element vary from light element as hydrogen to heavy element as uranium in addition to17 elements manufactured by atomic reactions and thus the total of elements are 109.