Lecture 2

The biochemical basis of lifeis composed of :

1- Organic compounds

2- Inorganic compounds

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

All share in containing carbon elementwhich is associated with hydrogen and oxygen.

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1-1 Carbohydrates:The function of carbohydrates lies in being the first source of energy in the cell.

Carbohydrates are classified into the followingsections:

Carbohydrates

Monosaccharides Disaccharides Polysaccharides

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-- 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 (CH2O)n, where n can be 3, 5 or 6

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-- Monosaccharides:

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Dihydroxyacetone Ribose

-- Monosaccharides:

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- 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

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Disaccharide Monosaccharides

α-lactose * α-glucose + β-galactose

maltose α-glucose + α-glucose

sucrose α-glucose + α-fructose

- 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.

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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.

1-2 Lipids

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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).

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1-2 Lipids

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The terms saturated and unsaturated lipids refer to the number of bonds on each carbon atom that makes up the fatty-acid tail of the molecule. Saturated lipids are solid at room temperature. Unsaturated fats are liquid at room temperature.

Lipids serve as sources of stored energy & structural components of cellular membranes

1-2 Lipids

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

The resulting combination of these elements together isso-called amino acids which are the basic units ofcomposition and function in proteins.

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

R

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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, Phenylalanine, Therionine, Treptophan, Valine.

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

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1-3 Proteins:

1-3 Proteins:The 20 amino acids

1-3 Proteins:Functions of proteins:

•Contribute to the mechanical structure of animals, including humans, e.g. keratin in hair.•Control the types and rates of chemical reactions in living things; then they are called enzymes, e.g. amylase.•Are important components of the human immune system, e.g. immunoglobins

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

The subunit structure of nucleic acid is Nucleotide.DNA nucleotide is composed of deoxyribose sugar, phosphate group and nitrogenous base (A, G, C, T).RNA nucleotide is composed of ribose sugar, phosphate group and nitrogenous base (A, G, C, U).

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1- 4 Nucleic acids

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

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

Vitamins can be divided in terms

Of their melting in two groups :

Melting in fat, such as Vitamins

(A ,D, K ,E )

melting in water,

such as Vitamin

(C ,B , Biotin and folic acid )

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1- 5 Vitamins

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Nutrient Function Sources

Vitamin A

Needed for vision, healthy skin, bone and tooth growth and immune

system health

Vitamin A from animal sources (retinol): fortified milk, cheese, cream, butter, fortified

margarine, eggs, liverBeta-carotene (from plant sources): Leafy, dark green vegetables; carrots, winter squash, sweet

potatoes, pumpkin

Vitamin DNeeded for proper

absorption of calciumEgg yolks, liver, fatty fish, fortified milk,

fortified margarine. When exposed to sunlight, the skin can make vitamin D.

Vitamin EAntioxidant; protects cell

wallsPolyunsaturated plant oils (soybean, corn,

cottonseed, safflower); leafy green vegetables; wheat germ; whole-grain products; liver; egg

yolks; nuts and seeds

Vitamin KNeeded for proper blood

clottingLeafy green vegetables and vegetables in the

cabbage family; milk

Fat-soluble vitamins

1- 5 Vitamins

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Nutrient Function SourcesThiamine

(vitamin B1)Part of an enzyme needed for

energy metabolism; important to nerve function

whole-grain or enriched breads and cereals, nuts and seeds

Riboflavin (vitamin B2)

Part of an enzyme needed for energy metabolism; important for

normal vision and skin health

Milk and milk products; leafy green vegetables; whole-grain, enriched

breads and cereals Biotin Part of an enzyme needed for

energy metabolism Widespread in foods; also produced

in intestinal tract by bacteriaFolic acid Part of an enzyme needed for

making DNA and new cells, especially red blood cells

Leafy green vegetables and legumes, seeds, orange juice, and liver

Cobalamin (vitamin B12)

Part of an enzyme needed for making new cells; important to

nerve function

Meat, poultry, fish, seafood, eggs, milk and milk products; not found

in plant foodsAscorbic acid (vitamin C)

Antioxidant; part of an enzyme needed for protein metabolism; important for immune system

health

Found only in fruits and vegetables, especially citrus fruits, strawberries, peppers, tomatoes, potatoes, lettuce,

papayas, mangoes, kiwifruit

Water-soluble vitamins

2- Inorganic compounds:Inorganic compounds are typically

, and 2O, O2without carbon atoms. Hcompounds NaCl are examples of inorganic compounds.

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.

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The chemical element is defined as the materialthat can not be analyzed into simpler

substance by chemical reaction.

The universe contains 92 element vary from light element as hydrogen to heavy elementas uranium in addition to 17 elements manufactured by atomic reactions and thus the total of elements are 109.

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Watch this video

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Exercise

1. Carbohydrates, proteins, lipids, and nucleic acids are

all examples of ________ compounds.

2. In living organisms, lipids function mainly as

________

3. ________ & ________ are fat-soluble vitamins

4. The general formula for lipids is ________

5. The general formula for amino acids is ________

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Exercise

6. The general formula for Monosaccharides is ________

7. Cellulose and starch belong to ________

8. ________ is the organic component contains carbon,

hydrogen and oxygen in addition to the element phosphorus.

9. Proteins are the organic components contain carbon,

hydrogen and oxygen in addition to other secondary

elements as________ , ________ & ________

10. Nucleic acids are made up of ________28