CH 3: The Molecules of Cells

1. CH 3: The Molecules of Cells

2. Molecules of Life • The molecules of life are all organic compounds….meaning carbon containing • Carbohydrates: C, H, O • Lipids: C, H, O • Proteins: C, H, O, N, S • Nucleic acids: C, H, O, N, P

3. Carbon (3.1) • In compounds, C always forms 4 covalent bonds • Diagramming C compounds • C to C single bonds can rotate freely • Allows C compounds to form rings • C to C double bonds are rigid

4. Hydrocarbons • Hydrocarbons – compounds containing only C and H • Are hydrocarbons polar or nonpolar? • Are they hydrophilic or hydrophobic?

5. Isomers • Isomers – compounds with same formula, but different arrangement of the atoms • Isomers differ in properties and in biological activity

6. Functional Groups • Molecules of life are all substituted hydrocarbons • (Most) functional groups contain atoms other than C and H • Many are polar and change properties of the compound • Substitute functional group(s) for hydrogens

7. Six main functional groups are important in the chemistry of biological molecules: POLAR Functional groups • Hydroxyl group (OH) • Carbonyl group (C=O) • May be an aldehyde or ketone • Carboxyl group (COOH) - Acidic • Amino group (NH2) - basic • Phosphate group (OPO3) NONPOLAR Functional Group • Methyl (CH3)

9. Functional Groups Impact Function • Differences in position and types of functional groups greatly impact the function of the molecule Estradiol Female lion Testosterone Male lion

10. Classes of Chemical Reactions (3.3) 1. Rearrangement • Convert one isomer to another • Example • Reaction that converts glucose to fructose • Reaction is used to make high fructose corn syrup

11. Making Polymers 2. Dehydration* Reaction - links molecules together • A covalent bond forms between molecules and water is removed • Reaction by which monomers are joined to form larger molecules • Examples: • *Also called a condensation reaction

13. Breaking Polymers 3. Hydrolysis reaction – breaks down larger molecules • Water is added to a larger molecule to split off a smaller molecule. • Reaction involves breaking a covalent bond by adding water • Reverse of a dehydration reaction Example from lab this week

15. MonomersPolymer Formed • Monosaccharides Di & Polysaccharides • Fatty acids Triglycerides • Amino acids Proteins • Nucleotides Nucleic acids

16. SUMMARY • Monomers are linked by condensation reactions (also called dehydration reactions) • A water molecule is produced • A covalent bond is formed between monomer units • Polymers are broken down to monomers by the reverse process, hydrolysis • A water molecule is broken • A covalent bond is broken between monomer units

17. Carbohydrates (3.4-3.7) • Class of molecules with many hydroxyl groups (OH) and one carbonyl group (C=O) • Consider 3 Classes of Carbohydrates • Monosaccharides • Disaccharides • and other moderate size carbohydrates • Polysaccharides

18. Monosaccharides • General Formula: CnH2nOn • Typically 3-7 carbons long • Mnay –OH groups and… • One carbon is attached to an aldehyde or ketone group • Form rings – see pg 37

19. Common Monosaccharides Pentose monosaccharides: • Deoxyribose – sugar in DNA • Ribose – sugar in RNA HexoseMonosaccharides: • Glucose all isomers of • Fructose C6H12O6 • Galactose

21. 6 C - Hexose Sugars • All isomers of C6H12O6 • Glucose - • Blood sugar • Primary source of energy for cells • Fructose • “Fruit” sugar • Sweetest of all the sugars • Galactose • Formed when lactose is digested

22. Glucose is an aldehyde sugar Aldose Fructose is a ________ sugar _____ose

23. Disaccharides • Formed when 2 monosaccharides are joined in a ___________ reaction. • One sugar gives up a H and the other a -OH • 3 Disaccharides to know • Sucrose = glucose - • Lactose = glucose - • Maltose = glucose -

24. Synthesis of Maltose

25. Disaccharides • Sucrose = glucose covalently bonded to a fructose • Table sugar • In the small intestines the enzyme sucrase catalyzes the hydrolysis of the bond between glucose and fructose • In the lab this bond can be broken by…..?

26. Disaccharides Lactose = glucose-galactose • Milk sugar • The enzyme lactase catalyzes the hydrolysis of the bond between glucose and galactose. • Individuals who do not make the enzyme lactase are lactose intolerant.

27. Lactose Intolerance • Populations at greatest risk: • Asian - ~ 90% • African descent - ~ 75% • Hispanic, Native Americans - ~ 75%

28. Last Disaccharides • Maltose = glucose-glucose • Found in germinating grains, malt products • Formed when starch is hydrolyzed (digested)

29. Oligosaccharides • ~20- 30 monosaccharides long • found on the outside of the plasma membrane, Often branched, Help cells recognize each other

30. Polysaccharides • All polymers of glucose • Differ in: • Function • Type of bonding between glucose • Length of the glucose chain • Frequency of branching • Incidence of coiling

31. Major Polysaccharides Glycogen Starch Cellulose

32. Glycogen • Function – animal storage form of glucose • Made and stored in: • Liver • Source of glucose for the entire body • Muscle cells • Source of glucose for muscle cells only

33. Glycogen • Structure • ~ 1 million glucose joined by covalent bonds called alpha glycosidic bonds • We have the enzymes needed to hydrolyze the alpha bonds in glycogen • Highly branched • Branch every 5-6 glucose

34. Starch • Function – plant storage form of glucose • Structure – ~100, 000 glucose joined by covalent bonds called alpha glycosidic bonds • Molecules are either coiled or branched – depending on type of starch

35. Cellulose • Function – structural polysaccharide • Component of cell walls • Structure • Long chains of glucose joined by covalent bonds called beta glycosidic bonds • We do not have the enzymes needed to hydrolyze beta bonds

36. Cellulose • Structure • Hydrogen bonds link chains to each other to form fibers • The fibers then form bundles • See page 39 • The resulting structure is VERY strong.

37. Cellulose

38. Lipids (3.8 – 3.10) • Water insoluble components of cells • Primarily hydrocarbon, nonpolar substances • Classes of Lipids: • Triglycerides (fats) and fatty acids • Phospholipids • Sterols • Waxes (no coverage)

39. Triglycerides and Fatty Acids • Triglycerides are made by linking 3 fatty acids to a glycerol molecule Triglyceride

40. Fatty Acids • Fatty Acids (FA) • Long hydrocarbon chains with a carboxylic acid head. • Saturated FA: all carbon to carbon single bonds • Unsaturated FA: at least one carbon to carbon double bond

41. Fatty Acids Red = polar head Black = nonpolar tail

42. Triglycerides: (TG) • Function: storage form of energy • Structure: 3 fatty acids covalently bonded to a glycerol backbone • 3 FA are often different from each other • FA determine the properties of the TG • Mostly unsaturated FA => liquid (oil), healthier • Mostly saturated FA => solid, heatlh issues • Trans FA => health issues, formed in hydrogenation reaction

43. Triglyceride

44. Phospholipids (3.9) • Function: major component of plasma membrane • Structure: ………….

45. Steroids • Steroids (sterols) • Functions vary • Examples of sterols include: • Hormones – testosterone, estrogen • Vitamin D • Cholesterol • Structure: 4 linked rings……..

46. Steroids General steroid structure Cholesterol

47. Proteins • Functions/examples of proteins: • Enzymes • Antibodies • Hemoglobin • Insulin • Component of cell membranes • Hair, nails, cartilage

48. Proteins • Structure: • Chain of covalently bonded amino acids (a.a) • Bond between a.a. called a peptide bond • 20 different amino acids…………..

49. Amino Acid Structure Amino group Carboxyl (acid) group

50. The structure of the R group determines the specific properties of each amino acid Leucine (Leu) Serine (Ser) Aspartic acid (Asp) Hydrophobic R Group Hydrophilic R groups