1.2 The Chemicals of Life

1. 1.2 The Chemicals of Life With the exception of water, virtually all chemicals of life are CARBON-BASED. Compounds that contain carbon (other than CO2 and a few other exceptions) are called organic compounds. Cells use these compounds for: GENETIC INFORMATION METABOLIC PROCESSING ENERGY STRUCTURE COMMUNICATION

2. CARBON • Carbon is a small, light element • Carbon has 4 single valence electrons and can form up to 4 stable covalent bonds. • Molecules containing only carbon and hydrogen are known as HYDROCARBONS Large hydrocarbons tend to be non-polar due to the symmetrical arrangement of their bonds.

3. BONDING CAPACITY • Other elements such as hydrogen, oxygen, sulfur and phosphorus may also attach to the carbon backbone.

4. FUNCTIONAL GROUPS • Many organic molecules contain rings or chains of carbon with additional hydrogen, oxygen, sufer and phosphorus atoms attached. • These additional atoms are called FUNCTIONAL GROUPS

5. FUNCTIONAL GROUPS • FUNCTIONAL GROUPS give the organic molecule specific chemical properties. Chemical reactions between organic molecules usually involve the molecules functional group.

6. FUNCTIONAL GROUPS

7. CAN YOU IDENTIFY THE FUNCTIONAL GROUPS? Phosphate group Amino group Hydroxyl group Phosphate group Hydroxyl group Sulfhydryl group Amino group Carboxyl group

8. FUNCTIONAL GROUPS • The hydroxyl group (-OH) and carboxyl group (-COOH) are POLAR • this is why SUGARS and ALCOHOLS are highly soluble in water (because they contain the polar hydroxyl group) Glucose molecule Ethanol molecule

9. BIOLOGICAL MACROMOLECULES • A very large organic molecule is called a macromolecule. • There are four major groups of biologically important macromolecules: • 1. Carbohydrates • 2. Lipids • 3. Proteins • 4. Nucleic Acids

10. BIOLOGICAL MACROMOLECULES • All macromolecules are made up of smaller subunits… POLYMER = a large molecule composed of long chains of smaller subunits.

11. CARBOHYDRATES • Carbohydrates are molecules that contain CARBON, HYDROGEN, and OXYGEN in a 1:2:1 ratio, and are primarily used by living organisms as a source of energy. CARBOHYDRATES = ENERGY!! Organisms also use carbohydrates as building materials, and as cell surface markers for cell-to-cell identification and communication.

12. CARBOHYDRATES • Plants produce carbohydrates by the process of photosynthesis! • (to use as ENERGY!)

13. CARBOHYDRATES • Carbohydrates may be classified into 3 main groups: • monosaccharides– simple sugars • oligosaccharides– sugars containing 2 or 3 simple sugars attached by covalent bonds called glycosidic linkages • polysaccharides– polymers composed of several hundred to several thousand monosaccharide subunits

14. MONOSACCHARIDES • Monosaccharides are composed of a single chain of carbon atoms to which hydroxyl groups are attached. Monosaccharides also contain a carbonyl group (-COH or –CO).

15. MONOSACCHARIDES • monosaccharides can be distinguished by the number of carbon atoms they possess 3-carbon sugar = “triose” 5-carbon sugar = “pentose” 6-carbon sugar = “hexose”

16. MONOSACCHARIDES • monosaccharides can also be distinguished by the spatial arrangement of their atoms • Molecules with the same chemical formula but with a different arrangement of atoms are called ISOMERS Glucose, galactose and fructose all have the chemical formula C6H12O6 but have atoms that are arranged differently.

17. MONOSACCHARIDES • Monosaccharides with 5 or more carbons are linear in the dry state, but when dissolved in water form a ring structure. Glucose (C6H12O6) is a simple sugar with a 6-carbon ring structure.

18. OLIGOSACCHARIDES - Two or three simple sugars held together by glycosidic linkages A glycosidic linkage occurs between a HYDROGEN from one sugar and a HYDROXYL from the other sugar. Via a condensation reaction, the two sugars are joined and a water molecule is produced. 1-4 glycosidic linkage

19. OLIGOSACCHARIDES • Important disaccharides include: MALTOSE, SUCROSE & LACTOSE Lactose is the sugar found in milk! Maltose is found in grains and used in the production of beer. Sucrose is table sugar! Sucrose is also used by plants to transport glucose from one place to another.

20. POLYSACCHARIDES • Also known as “complex carbohydrates” • are monosaccharide polymers – composed of several hundred to several thousand monosaccharide subunits held together by glycosidic linkages! Some polysaccharides are straight chains, whereas others are branched!

21. POLYSACCHARIDES • Polysaccharides serve 2 important functions in living cells! • 1. ENERGY STORAGE! • 2. STRUCTURAL SUPPORT! • Examples of storage polysaccharides: • STARCH • GLYCOGEN • Examples of structural polysaccharides: • CELLULOSE • CHITIN

22. POLYSACCHARIDES Starch is an energy storage molecule in plants. Cellulose gives structural integrity to the plant cell wall. Glycogen is used for energy storage in human muscles. Chitin gives structural integrity to the hard exoskeletons of insects.

23. POLYSACCHARIDES • Plants store the sun’s energy as glucose – when they produce more glucose than is immediately required, they store glucose as STARCH – a polymer of glucose Humans and animals possess digestive enzymes which are able to break the glycosidic linkages between glucose molecules in starch – thus using glucose for energy via cellular respiration. Starch is the main energy storage molecule in plants. It is a mixture of amylose and amylopectin.

24. POLYSACCHARIDES Humans DO NOT possess digestive enzymes that enable them to break down cellulose. THIS IS WHY HUMANS CAN’T EAT GRASS! (…but cows can?!?!?!) Some animals, such as cows, sheep and rabbits possess digestive enzymes which enable them to break down cellulose and convert it to glucose for energy. When eating fruit and vegetables, humans break down the starch for energy needs, and the cellulose passes through the digestive tract with out being digested. Also known as FIBRE, this helps to scrape our inner intestinal walls and promotes healthy and regular elimination of wastes!

25. LIPIDS • LIPIDS = molecules made up of CARBON, HYDROGEN and OXYGEN • LIPIDS have a much higher proportion of HYDROGEN atoms than oxygen or carbon. Due to the smaller proportion of polar O-H bonds and higher proportion of the non polar C-H bonds – fats are NON POLAR!

26. LIPIDS • LIPIDS • Store MORE chemical energy than carbohydrates!!! • Are used in the body for storing energy, building membranes and other cell parts and are also chemical signalling molecules. • Lipids are soluble in NONPOLAR solvents (like oil) • Lipids are insoluble in water and aqueous solutions.

27. LIPIDS • The 4 families of lipids include… WAXES FATS STEROIDS PHOSPHOLIPIDS

28. LIPIDS – OILS & FATS • Oils and fats are composed of lipid molecules called triglycerides. (this is also how plants store fat) • Triglyceridesare made up of 4 subunits: • A GLYCEROL backbone • 3 FATTY ACID chains

29. LIPIDS – OILS & FATS • AGLYCEROL molecule • Is a 3 carbon molecule with a hydroxyl group attached to each carbon

30. LIPIDS – OILS & FATS A FATTY ACID molecule • Is a long chain of carbon and hydrogen atoms with a carboxyl group at one end. Hydrocarbon chains usually have 16-18 C atoms

31. LIPIDS – OILS & FATS • To form a TRYGLYCERIDE, a fatty acid is attached to each of the 3 hydroxyl groups of glycerol. This is a CONDENSATION REACTION 3 Water molecules (H2O) are produced as a bi-product of this reaction. The resulting bond is called an ESTER LINKAGE – and the process is known as esterification.

32. LIPIDS – OILS & FATS • FATTY ACIDScan differ in • length • single vs. double bonds between the carbons Fatty acids that only have single bonds will be straight. Fatty acids that possess double bonds will be bent.

33. LIPIDS – OILS & FATS • Based on the presence of single or double bonds, we can classify FATTY ACIDS into two main categories. SATURATED TRIGLYCERIDES UNSATURATED TRIGLYCERIDES

34. LIPIDS – OILS & FATS • Saturated triglycerides contain fatty acids with ONLY single bonds between carbon atoms. • Unsaturated triglycerides contain fatty acids with double bonds between two carbon atoms. • Polyunsaturated triglycerides contain fatty acids with more than one double bond.

35. LIPIDS – OILS & FATS • Sources of fat in our diet… Cooking Oils – polyunsaturated fats Animal meats – saturated fats Margarine – saturated fat

36. LIPIDS – PHOSPHOLIPIDS • Phospholipids play a key role in the structure of CELL MEMBRANES!!! Cell membranes are made up of a PHOSPHOLIPID BILAYER ie – a double layer of phospholipids.

37. LIPIDS – PHOSPHOLIPIDS • Phospholipids are similar to triglycerides except that an additional functional group replaces one of the fatty acids. Phospholipids are composed of: - a glycerol molecule - two fatty acids - a highly polar phosphate group In a phospholipid, one of the fatty acids is replaced by a PHOSPHATE GROUP.

38. LIPIDS – PHOSPHOLIPIDS The POLAR head is HYDROPHILIC – ie: “water loving” The NONPOLAR tail is HYDROPHOPBIC – ie: “water fearing” When placed in water, phospholipids will arrange themselves with polar heads facing outward and nonpolar tails facing inward (away from the water).

39. LIPIDS – PHOSPHOLIPIDS • One function of the cell membrane is to separate two water compartments: • the extracellular fluid • the cell’s cytoplasm • The cells DOUBLE LAYER of phospholipids allows the hydrophilic heads to mix with water in both compartments and tails to mix with one another in the center of the bilayer. Water and other polar and ionic materials CANNOT pass through the bilayer because of the highly non polar center. The cell membrane will contain hydrophilic pores that form channels though which charged materials can pass.

40. QUESTION!! • What do Jell-O, antibodies, feathers, blood clots, egg whites and finger-nails have in common?!?!?!?!?

41. PROTEIN • They’re ALL made up of PROTEIN!!!!!!!!! Proteins are the most diverse molecules in living organisms and among the most important!

42. PROTEIN • The genetic information in DNA codes specifically for the production of proteins and nothing else. • Proteins are structural building blocks • Proteins are involved in almost everything that the cell does! • Cells contain thousands of proteins, each performing a specific task

43. PROTEIN • Examples of protein in the body: • ENZYMES = biological catalysts • IMMUNOGOBULINS = protect animals against foreign microbes and cancer cells • CARRIER PROTEINS = help transport materials through cell membranes • HEMOGLOBIN = allows red blood cells to carry oxygen • KERATIN = structural protein found in hair and nails • FIBRIN = the protein that helps blood clot • COLLAGEN = the protein component of bones, skin, ligaments and tendons

44. PROTEIN • Different proteins have various functions… but all proteins have the same basic structure. • Proteins arepolymers of amino acids • PROTEINS ARE MADE UP OF AMINO ACIDS!!!!!!!!!!

45. PROTEIN STRUCTURE • AMINO ACIDS are small molecules that contain • A central carbon atom that has attached: • An Amino Group • A Carboxyl Group • a Hydrogen Atom • a side chain (which is different in each different amino acid) NH2 COOH H R There are 20 different R groups possible and therefore there are 20 different amino acids!!!!

46. PROTEIN STRUCTURE • AMINO ACIDS CENTRAL CARBON ATOM AMINO GROUP CARBOXYL GROUP HYDROGEN ATOM R-GROUP or Side Chain

47. PROTEINS • Overall there are 20 different AMINO ACIDS • Different proteins are made up of different combinations of the 20 amino acids.

48. PROTEINS • Of the 20 amino acids, we say that there are 8 essential amino acids. They are called essential amino acids because the body cannot produce them naturally, and therefore, we must get them from FOOD SOURCES!!!!!!

49. PROTEINS • Proteins consist of one or more amino acid polymers that have twisted and coiled into a specific shape = CONFORMATION An amino acid polymer is often referred to as a POLYPEPTIDE and the bond between amino acids in a polypeptide are referred to as PEPTIDE BONDS. The 3D shape of the protein determines its function.

50. PROTEINS • Peptide bonds are formed by a condensation reaction between the amino group of one amino acid and the carboxyl group of an adjacent amino acid.