The Chemistry of Life

1. The Chemistry of Life Part I – Macromolecules and Carbohydrates

2. Atoms and Elements • Physical world composed of 92 elements • Simplest building blocks • Atom - smallest unit of an element

3. Atomic Components • Atoms are composed of 3 subatomic particles • Electrons – negatively charged • Protons – positively charged • Neutrons – no charge (neutral) • Protons & neutrons are contained in the nucleus • Electrons orbit the nucleus • Gain or loss of an electron: ion

4. Atomic and Mass Numbers • Atomic Number: Number of Protons • Determines the element’s properties • Mass Number: Number of Protons + Number of Neutrons • Isotopes: different numbers of neutrons • Unstable isotopes: Radioisotopes • Gain or loss of an electron: ion

5. Covalent Bonds • Electrons are held in shells • Atoms are stable when the shells are filled • Atoms share elec-trons to fill these shells

6. Noncovalent Bonds • Link molecules together (intermolecular) • Much weaker than covalent • Much more prevalent • Hydrogen bonds: very common in biology • Attraction between partial charges • Hold biological molecules together • Ionic bonds: form between charged particles (Ions)

7. Organic Chemistry • Carbon makes up most of the mass of living organisms • Carbon is an ideal element as the foundation for life because of its ability to make bonds with up to four other elements • Carbon has multiple sites for connections that allow carbon-containing molecules to take an almost infinite variety of shapes

9. Organic Chemistry • Carbon atoms are often involved in covalent bonding • They are symbolized by a short line indicating a shared pair of electrons

10. Organic Chemistry • A double bond is when an element enters into a bonds involving two pairs of shared electrons • A double bond is symbolized by two horizontal lines

11. Carbon-based Molecules • Biomolecules are mainly C and H • Carbon chains can be very long • O, S, P, and N are also present • These comprise functional groups • Functional groups allow molecules to interact • Biomolecules are combined to form polymers

12. Biological macromolecules • Four major classes • Carbohydrates • Proteins • Lipids • Nucleic acids • Know • Monomers for each class of molecule • Function(s) of each class of molecule • An example of each class of molecule

13. Monomers and polymers • Monomers are building blocks • Like cars of a train • Polymers are chains of monomers • The entire train

15. Biological macromolecules • Synthesis • Dehydration to join monomers together • Remove water • Process adds energy to molecules • Breakdown • Hydrolysis to split monomers apart • Add water • Process releases energy from molecules

18. Carbohydrates • Sugars and their polymers • composed of carbon, hydrogen, oxygen • Hence the name “carbo – hydrate” • Sugars play multiple roles in an organism • provide energy • form important structural components of the body

19. Carbohydrates • Monomers are monosaccharides • Simplest type of sugar • Glucose • Source of energy • Produced by photosynthesis • Fructose • Fruit sugar • Also a source of energy

20. Carbohydrates • Simple sugars have the ratio of one C to two H to one O (CH2O) • An example of this is glucose: C6H12O6

21. Carbohydrates • Monosaccharides can combine to form: • Disaccharides • Lactose – milk sugar • Sucrose – table sugar • Maltose – from starch • When you chew bread slowly, it becomes sweet tasting • This is because an enzyme, called amylase, in your saliva begins breaking down the starch into units of maltose.

22. Sucrose (Table Sugar) – A common disaccharide is made from two glucose molecules

24. Barley is the preferred grain for making beer. The barley seeds must be "malted" before they can be used in the brewing process. Malting is a process of bringing grain to the point of its highest possible starch content by allowing it to begin to sprout roots and take the first step to becoming a photosynthesizing plant. At the point when the maximum starch content is reached, the seed growth is stopped by heating the grain to a temperature that stops growth, but allows an important natural enzyme to remain active. Barley, once "malted," is very high in the type of starches that the enzyme can convert quite easily into the disaccharide called Maltose. This sugar is then fermented or metabolized by yeasts to create the carbon dioxide and ethyl alcohol in BEER.

25. Carbohydrates • Monosaccharides can combine to form: • Polysaccharides • Starch: energy storage • Amylose: Plant starch • Glycogen: animal starch (liver) • Cellulose: structural carbohydrate • cell wall in plants • Chitin: structural carbohydrate • Cell walls in fungi • Exoskeleton of arthropods

28. Digesting Cellulose • Only microbes and a few animals can digest cellulose • Bacteria • Fungi • Protozoa • Insects such as silverfish • For other herbivores, there is no energy available

29. Digesting Cellulose • Herbivores rely on symbiotic gut microbes to digest the cellulose and release the energy trapped in the chemical bonds. • Termites • Cattle and other ruminants

30. Termite Gut Symbionts

31. Worker Termite

32. Trichonympha

33. Chitin • Linear polymer of glucose monomers • Principle component of fungal cell walls • Also found in exoskeletons of arthropods • Insecta • Crustacea • Arachnida

34. Proteins • There are four groups of important macromolecules (large organic molecules) in all living things: • Carbohydrates • Proteins • Lipids • Nucleic acids

35. Proteins • Proteins are made by connecting different amino acids together • There are 20 amino acids • There are many combinations of amino acids – so there are many different proteins

36. Proteins • Monomers are amino acids • Joined together by peptide bonds • Function • Structural • Hair, nails • Cytoskeleton • Metabolic functions • Hemoglobin carries oxygen in red blood cells • Enzymes: regulate chemical reactions in cells

37. Amino Acids • Amino acids are the monomers of proteins

38. Proteins • The side group is different for each of the 20 amino acids • The side groups have different chemical properties – they give the amino acids different properties, like charge or polarity

39. Proteins • Notice that each different amino acid has a different side group and therefore different behavior • (These three amino acids are all hydrophobic…)

40. There are 20 different amino acids – here are just a few

41. Proteins • Polymers of amino acids are sometimes called polypeptides • Polypeptides are short chains of amino acids held together by a covalent bond called a peptide bond

42. Proteins • Amino acids • Core structure • Amino group – contains nitrogen • Acid group • R group • Unique reactive structure that defines the chemical properties of each amino acid.

43. Proteins • Long chains of amino acids joined by peptide bonds and folded into three dimensional shapes are called proteins.

45. Proteins • Structure of a protein • Primary structure • sequence of amino acids • Secondary structure • Chain of amino acids coils, twists • Tertiary structure • Chain forms a three dimensional shape • This shape is critical if the protein is to function normally

47. Proteins • Some large proteins such as hemoglobin are made of several smaller protein molecules • This is the quaternary structure of the protein

48. Proteins - classified by functions • Enzymes • catalytic activity and function • Transport Proteins • bind & carry materials across cell membranes • Storage Proteins • ovalbumin, gluten, casein, ferretin • Contractile  (Motor) • can contract, change shape • elements of cytoskeleton (actin, myosin, tubulin)

49. Cytoskeleton

50. Proteins - classified by functions • Structural (Support) • collagen of tendons & cartilage • elastin of ligaments • keratin of hair, feathers, & nails • fibroin of silk & webs