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Sylvia S. Mader Immagini e concetti della biologia 2 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 A3 – Biological molecules 3 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Carbon is the Basic Element of Biomolecules A single bacterial cell may contain up to 5000 different types of organic compounds. 4 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Carbon needs four electrons Every single carbon can bond with four other atoms Carbon-carbon bond is a covalent and stable bond, so it can form very long and strong carbon chains. 5 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The great variety of biomolecules Functional groups are specific combinations of atoms and confer typical features to the molecules. 6 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Isomers Chemical compounds with identical molecular formulas but different arrangements of atoms (or functional groups). Isomers react differently in chemical reactions 7 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Macromolecules Carbohydrates, lipids, proteins and nucleic acids are large molecules composed by molecular subunits linked together. Category Carbohydrates* Lipids Proteins* Nucleic acids* MACROMOLECULES Example Subunit(s) Polysaccharide Monosaccharide Fats Glycerol and fatty acids Polypeptide Amino acids DNA or RNA Nucleotide *The biggest macromolecules are polymers, large molecules composed of repeating structural units (monomers), normally connected by covalent bonds 8 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Polymers In the synthesis of a polymer, enzymes attach monomers to one another. This reaction is named dehydration as a molecule of water is freed. 9 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Polymers The opposite reaction is the degradation of a polymer. During this process a molecule of water is used to separate the two molecules. 10 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Carbohydrates Organisms use carbohydrates as instant sources of energy and structural materials. Carbohydrates are composed of Carbon (C), Hydrogen (H) and Oxygen (O) with the ratio 1:2:1 11 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Carbohydrates Simple carbohydrates, known as sugars, can be: •monosaccharides (a single molecule); •disaccharides (two molecules); •polysaccharides (several monosaccharides). 12 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Monosaccharide and disaccharides Simple carbohydrates provide quick energy Glucose is a simple sugar and a major source of energy for living organisms with formula C6H12O6. 13 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Monosaccharide and disaccharides Sucrose is an important disaccharide in plant’s nutrients circulation. It is compose by two monosaccharides (glucose and fructose) joined through dehydration. 14 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Monosaccharide and disaccharides Ribose (C5H10O5) and deoxyribose (C5H10O4) are found in DNA and RNA respectively and are both monosaccharides. Lactose is a disaccharide found milk and is formed from glucose and galactose (an isomer of glucose). 15 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Polysaccharides Starch: supply sugar contained in plants. Glycogen: supply sugar contained in animals and fungi. Cellulose: structure sugar contained in plants. Chitin: structure sugar contained in some animals. 16 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Lipids: energy storage and protection Lipids are insoluble in water as they are nonpolar. Fats and oils are rich energy-storage lipids. 17 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Lipids: fats and oils Unsaturated: have one or more double bonds in their fatty acid chain. Saturated: no double bonds in the fatty acid chain. 18 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Phospholipids: cell membrane component A phosphate group replaces the third fatty acid. Hydrophilic “head” Hydrophobic “tail” 19 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Steroids and waxes Steroids serve as cell membrane component or have hormonal function. Waxes are used to prevent water loss and assist in skin maintenance. 20 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Proteins are versatile biomolecules 1.Support: as keratin (in hair and fingernails) and collagen (in ligaments and tendons). 2.Metabolisms: as enzymes (catalyze reaction). 3.Transport: carrier proteins in the plasma membrane allow substances to enter or exit cells. 21 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Proteins are versatile biomolecules 4.Defense: antibodies destroy agents and prevent infections. diseases-causing 5.Regulation: some hormones, such as insulin, are regulatory proteins. 6.Motion: actin and myosin compose muscular tissues. 22 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Proteins: sequences of amino acids Amino acids are essentially composed of: •a central carbon •an amino group (-NH2) •an acid group (-COOH) •an R-group 23 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Polypeptides A single protein contains one ore more polypeptides 24 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Amino acids differ on the R-group 25 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Protein structure 26 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Nucleic Acids carry coded information Nucleotides are composed of a sugar, a phosphate group and a nitrogen base (Adenine, Guanine, Cytosine, Thymine, Uracil). 27 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 RNA - RiboNucleic Acid Convey coded information from DNA to ribosomes for the protein synthesis. Pentose sugar = ribose Nitrogen bases = are A, G, C and Uracile. 28 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 DNA - DeoxyriboNucleic Acid Is located in the nucleus, contains the genetic information and has a double helix structure. Pentose sugar = deoxyribose Nitrogen bases = are A, G, C and Thymine. 29 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Nucleic Acids 30 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 ATP: the energy currency ATP (adenosine triphosphate) consists of three parts: 1. An adenine (A) base; 2. A five-carbon ribose; 3. Three phosphate groups linked by covalent bonds. 31 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 ATP: the energy currency When the covalent bond of the third phosphate group is broken down by an enzyme, energy is released. 32 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012