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

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

4 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 A single bacterial cell may contain up to 5000 different types of organic compounds. Carbon is the Basic Element of Biomolecules

5 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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. Carbon needs four electrons

6 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Functional groups are specific combinations of atoms and confer typical features to the molecules. The great variety of biomolecules

7 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Chemical compounds with identical molecular formulas but different arrangements of atoms (or functional groups). Isomers react differently in chemical reactions Isomers

8 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Carbohydrates, lipids, proteins and nucleic acids are large molecules composed by molecular subunits linked together. *The biggest macromolecules are polymers, large molecules composed of repeating structural units (monomers), normally connected by covalent bonds MACROMOLECULES CategoryExampleSubunit(s) Carbohydrates*PolysaccharideMonosaccharide LipidsFatsGlycerol and fatty acids Proteins*PolypeptideAmino acids Nucleic acids*DNA or RNANucleotide Macromolecules

9 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 In the synthesis of a polymer, enzymes attach monomers to one another. This reaction is named dehydration as a molecule of water is freed. Polymers

10 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The opposite reaction is the degradation of a polymer. During this process a molecule of water is used to separate the two molecules. Polymers

11 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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 Carbohydrates

12 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Simple carbohydrates, known as sugars, can be: monosaccharides (a single molecule); disaccharides (two molecules); polysaccharides (several monosaccharides). Carbohydrates

13 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Glucose is a simple sugar and a major source of energy for living organisms with formula C 6 H 12 O 6. Monosaccharide and disaccharides Simple carbohydrates provide quick energy

14 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Sucrose is an important disaccharide in plant’s nutrients circulation. It is composed by two monosaccharides (glucose and fructose) joined through dehydration. Monosaccharide and disaccharides

15 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Ribose (C 5 H 10 O 5 ) and deoxyribose (C 5 H 10 O 4 ) 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). Monosaccharide and disaccharides

16 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.

17 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Lipids are insoluble in water as they are nonpolar. Fats and oils are rich energy-storage lipids. Lipids: energy storage and protection

18 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Unsaturated: have one or more double bonds in their fatty acid chain. Saturated: no double bonds in the fatty acid chain. Lipids: fats and oils

19 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 A phosphate group replaces the third fatty acid. Hydrophobic “tail” Phospholipids: cell membrane component Hydrophilic “head”

20 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Steroids serve as cell membrane component or have hormonal function. Waxes are used to prevent water loss and assist in skin maintenance. Steroids and waxes

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

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

23 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Amino acids are essentially composed of: a central carbon an amino group (-NH 2 ) an acid group (-COOH) an R-group Proteins: sequences of amino acids

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

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

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

27 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Nucleotides are composed of a sugar, a phosphate group and a nitrogen base (Adenine, Guanine, Cytosine, Thymine, Uracil). Nucleic Acids carry coded information

28 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Convey coded information from DNA to ribosomes for the protein synthesis. RNA - RiboNucleic Acid Pentose sugar = ribose Nitrogen bases = are A, G, C and Uracile.

29 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 DNA - DeoxyriboNucleic Acid Pentose sugar = deoxyribose Nitrogen bases = are A, G, C and Thymine. Is located in the nucleus, contains the genetic information and has a double helix structure.

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

31 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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. ATP: the energy currency

32 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 When the covalent bond of the third phosphate group is broken down by an enzyme, energy is released. ATP: the energy currency