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

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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

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

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

25. Protein structure
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26. 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

27. 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

28. 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

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

30. 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

31. 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