The Molecules of Cells

1. The Molecules of Cells Part I – Introduction; Carbohydrates; Lipids

2. Organic Chemistry • Study of carbon compounds • Occur in more than just living things • Are typically made by living things • Organiccompounds come fromorganisms • The chemistry that you study in HS is inorganic • Compounds that are found in the non-living world http://www.chemistryland.com/ElementarySchool/BuildingBlocks/BuildingOrganic.htm

3. Organic Compounds • The molecules of many organic compounds are large and may seem complex, but they are built up using small and relatively simple subunits YOU MUST BE ABLE TO IDENTIFY THESE STRUCTURES, you do not have to be able to draw them. Fatty Acid

4. Organic Compounds • Compounds containing carbon that occur in living organisms are regarded as organic. • Exceptions: carbonates and oxides of carbon (e.g. CO2)

5. A carbon atom has 4 valence electrons • Each valence electron can join with an electron from another atom to form a strong covalent bond. • Therefore, one carbon can form bonds with up to four other atoms.

6. Examples of carbon bonding to itself and to other atoms

7. Carbon can also form double and triple bonds • Two atoms share two pairs of electrons (double bond) or three pairs of electrons (triple bond)

8. The molecules formed when carbon bonds with itself and other atoms can be in the form of: • Chains • Rings • Various 3-D Shapes

9. Vary in Length Branching Double bonds Rings Isomers have the same molecular formula Isomers varying in their structures Have different properties Carbon Skeletons http://fig.cox.miami.edu/~cmallery/255/255chem/p2x1.jpg

10. small organic molecules  larger organic molecules From Monomers to Polymers

11. Molecular Diversity and Complexity of Living Organisms Results from: • variation in types of carbon skeletons that are possible • diversity of atoms of other elements that can be bonded to the skeletons at available sites

12. Important Concepts • Almost the entire dry weight of living organisms is composed of extremely large organic molecules (organic macromolecules). • Organic macromolecules are synthesized from simple subunits. • Organic macromolecules have many diverse structures and functions.

13. Major molecular components of an E. coli cell ComponentPercentage weight Water 70 Nucleic Acids 7 Protein 15 Carbohydrate 3 Lipid 2 Building Blocks and intermediates 2 Organic Ions 1 Organic Macromolecules 27%

14. Macromolecules • Synthesized from smaller subunits or building blocks • building block = monomer • macromolecule = polymer

15. Formation and Breakdown of Organic Macromolecules • Condensation • Joins monomers to form polymers - water is removed • Hydrolysis • Breaks down polymers to form monomers – water is added

16. Condensation Reactions • In a condensation reaction, 2 molecules are joined together to form a larger molecule • Water is also formed in the reaction • For example, 2 amino acids can be joined together to form a dipeptide by a condensation reaction • The new bond formed is a peptide linkage • Further condensation reactions can link amino acids to either end of the dipeptide, eventually forming a chain of many amino acids • This is called a polypeptide www.pearsonsuccessnet.com activity 5.1 page 2

17. Condensation Reactions • In a similar way, condensation reactions can be used to build up carbohydrates and lipids • The basic subunits of carbohydrates are monosaccharides • 2 monosaccharides can be linked to form a disaccharide and more monosaccharides can be linked to a disaccharide to form a large molecule a polysaccharide

18. Macromolecule FORMED by CONDENSATION • BROKEN BACK DOWN into subunits by HYDROLYSIS

19. glycerol + 3H20 triglyceride three fatty-acid tails • Fatty acids can be linked to glycerol by condensation reactions to produce lipids called glycerides • A max of 3 fatty acids can be linked to each glycerol, producing a triglyceride

20. Hydrolysis Reactions • Large molecules such as polypeptides, polysaccharides and triglycerides can be broken down into smaller molecules by hydrolysis • Polypeptides + water  dipeptides or amino acids • Polysaccharides + water  disaccharides or monosaccharides • Glycerides + water  Fatty acids + glycerol

21. Classes of Organic Macromolecules in Cells Carbohydrates Lipids Proteins Nucleic Acids

22. Carbohydrates • Building blocks (monomers) are simple sugars called monosaccharides. • Function in energy storage and cell structure

23. Glucose – a common monosaccharide H

24. Galactose – another common monosaccharide H H H H

25. Fructose – a third type of monosaccharide H H H

26. MonosaccharidesExamples • glucose • ribose • deoxyribose • fructose • galactose

27. Carbohydrate Polymer Synthesis and Breakdown

28. Three examples of disaccharides – maltose, lactose, and sucrose • The disaccharide (two monosaccharides linked) is the beginning of a carbohydrate polymer. • A carbohydrate polymer with more than two monosaccharides is a polysaccharide.

29. Disaccharides COMPONENT MONOSACCHARIDES DISACCHARIDE DESCRIPTION SUCROSE COMMON TABLE SUGAR GLU + FRU LACTOSE MAIN SUGAR IN MILK GALACTOSE + GLU MALTOSE PRODUCT OF STARCH HYDROLYSIS GLU + GLU CAN BE USED IN BEER FERMENTATION

30. First example of polysaccharide - cellulose

31. Second example of polysaccharide - starch

32. Third example of polysaccharide - glycogen

33. Some functions of carbohydrates in animals • Glucose: broken down in cellular respiration to release energy • Lactose: the sugar in the milk produced by mammals • Glycogen: energy store in liver and skeletal muscles

34. Some functions of carbohydrates in plants • Fructose: energy source and component of sucrose • Sucrose: unreactive, and so a good way to transport sugar throughout the plant • Cellulose: main component of the cell wall

35. Starch • repeating, branching macromolecule • carb storage for plants • For energy • Cellulose

37. Glycogen • storage of glucose in the liver and muscle • For energy • animals only

38. Chitin • forms exoskeleton of arthropods: insects, lobsters, shrimp, spiders

39. POLYSACCHARIDES • STARCH energy storage in plants α-glucose • CELLULOSE structure of plant cell walls β-glucose • GLYCOGEN energy storage in animals α-glucose • CHITIN structure of fungi cell walls & β-glucose exoskeleton of insects Polysaccharide Description Monomer Unit