Immagini e concetti della biologia Sylvia S. Mader Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

A3 – Biological molecules 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. 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. 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. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Isomers react differently in chemical reactions Chemical compounds with identical molecular formulas but different arrangements of atoms (or functional groups). Isomers react differently in chemical reactions 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. MACROMOLECULES Category Example Subunit(s) Carbohydrates* Polysaccharide Monosaccharide Lipids Fats Glycerol and fatty acids Proteins* Polypeptide Amino acids Nucleic acids* DNA or RNA Nucleotide *The biggest macromolecules are polymers, large molecules composed of repeating structural units (monomers), normally connected by covalent bonds 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. 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. 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 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). 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. 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. 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). 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. 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. 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. 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” 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. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Proteins are versatile biomolecules 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. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Proteins are versatile biomolecules Defense: antibodies destroy diseases-causing agents and prevent infections. 5.Regulation: some hormones, such as insulin, are regulatory proteins. 6.Motion: actin and myosin compose muscular tissues. 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 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Polypeptides A single protein contains one ore more polypeptides Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Amino acids differ on the R-group Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Protein structure 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). 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. 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. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Nucleic Acids Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

ATP: the energy currency ATP (adenosine triphosphate) consists of three parts: An adenine (A) base; A five-carbon ribose; Three phosphate groups linked by covalent bonds. 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. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012