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PROTEINS

Proteins are a large molecules made up of one or more chains of amino acids.

Amino acids are joined together by a peptide bond.

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Union of a few amino acids is a peptide.

Chains of many amino acids is a polypeptide.

Proteins that contain other kinds of molecules are called Conjugated proteins.

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The structures of proteins

The primary structure of proteins is determinated by the sequence of amino acids.

The secondary structure of proteins depends on whether the protein chains are straight or folded up in a particular pattern.

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Functions of proteins

- Structure (i.e. myosin, keratins)

- Catalysis (enzymes)

- Control (insulin)

- Energy (albumin, casein)

- Transport (haemoglobin)

- Protection (antibody)

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Denaturation of proteins

Denaturation occurs when the normal bonding patterns are disturbed causing the change of the protein shape .

This can be caused by changes in temperature, pH or salt concentration.

If the protein is not severely denaturated, it may regain its normal structure.

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CARBOHYDRATES

Carbohydrates are organic compounds and they have the general formula Cx(H2O)y.

Sugars are the simplest carbohydrates.

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Monosaccharides

Disaccharides

Oligosaccharides

Polysaccharides

Simple sugars

Two monosaccharides linked together

Few monosaccharides linked together

Long chains of monosaccharides

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Functions of carbohydrates

- Intermediates for the conversion of food into energy

- Energy storage molecules in plants

They form cell walls in plant cells
They are structural components in the body shells of many invertebrates
They occur in the surface coat of animal cells and in bacteria cell walls

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Carbohydrates are produced during photosynthesis.

Photosynthesis is the process by which green plants produce carbohydrates from CO2, O2 and H20 using the energy from sunlight.

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LIPIDS

Lipids are organic compounds that are insoluble in water but soluble in organic solvents.

Simple lipids are esters of fatty acids and various alchols.

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Functions of lipids

Storage form for metabolic energy (triglycerides)
Components of membranes
Messagers (prostaglandis, steroid hormones)

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CLASSIFICATION OF LIPIDS

Fat and oils

Waxes

Compoud lipids

Esters of fatty acids and alcohols containing addictional groups ( i.e. phospholipids and glycolipids)

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Some important vitamins are lipids.

Vitamins are substances used by living cells to aid enzyme reactions.

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NUCLEIC ACIDS

DNA

(Deoxyribonucleic acid)

RNA

(ribonucleic acid)

DNA and RNA store and transfer genetic information

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DNA is the genetic material and contain the informations necessary for the synthesis of proteins.

Before protein can be synthesized, the instructions in DNA must first be copied to messenger RNA.

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Structure and composition of nucleic acids

Nucleic acids are composed of units called nucleotides linked together.

Each nucleotide contains a base, a sugar (deoxyribose in DNA and ribose in RNA) and a phosphate group.

DNA is composed of two strands that are twisted forming a configuration that is called double helix.

Structure and composition of nucleic acids

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THE FLOW OF GENETIC INFORMATION

DNA

RNA

Proteins

Transcription

Translation

Replication

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BIBLIOGRAPHY

P. Briano – A Matter of life - English for Chemistry, Biology and Biotechnology – Edisco

P. Vaudo – On the Lab – Ed. Yuvenilia

D. L. Nelson, M. M. Cox – Introduzione alla Biochimica di Lehninger – Ed. Zanichelli

Author: Gabriele