Immagini e concetti della biologia Sylvia S. Mader Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

A3 – Biological molecules Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

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, 2018

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, 2018

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, 2018

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, 2018

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, 2018

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, 2018

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, 2018

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, 2018

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, 2018

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, 2018

Monosaccharide and disaccharides Sucrose is an important disaccharide in plant’s nutrients circulation. It is composed by two monosaccharides (glucose and fructose) joined through dehydration. Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

Monosaccharide and disaccharides Ribose (C5H10O5) and deoxyribose (C5H10O4) are found in RNA and DNA respectively and are both monosaccharides. Lactose is a disaccharide found in milk and is formed from glucose and galactose (an isomer of glucose). Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

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, 2018

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, 2018

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, 2018

Phospholipids: cell membrane component A phosphate group replaces the third fatty acid. Hydrophilic “head” Hydrophobic “tail” Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

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, 2018

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. 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, 2018

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, 2018

Polypeptides A single protein contains one ore more polypeptides Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

Amino acids differ on the R-group Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

Protein structure Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

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, 2018

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, 2018

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, 2018

Nucleic Acids Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

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, 2018

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, 2018