The Molecules of Life

1. The Molecules of Life Carbohydrates, Lipids, Proteins, and Nucleic Acids

2. What is a molecule? • A collection of atoms bound together by covalent bonds. • Can be very small, 2 atoms, or very large, millions of atoms. • Exist in great diversity • Can be categorized by structure and function

3. Major Categories of bio-molecules • Carbohydrates – think sugars like glucose • Lipids – think fats and oils • Proteins – think muscle and amino acids • Nucleic Acids – think DNA and RNA

4. Other key terms… Polymer – a long molecule consisting of many similar or identical building blocks (monomers) Condensation Reaction (dehydration synthesis)– the formation of a covalent bond between molecules, produces water as a byproduct Hydrolysis – the breaking up of a covalent bond, uses water molecules

5. Carbohydrates • Include sugars and polymers of sugars • Commonly form ring structures • Function in energy storage and structural support • Monosaccharide – a single carbohydrate • Disaccharide – two covalently bound carbohydrates • Polysaccharide – a polymer of carbohydrates

6. Monomers and Polymers

7. Glucose: monosaccharide, energy storage

8. Ribose: monosaccharide, part of DNA and RNA Ribose has 5 carbons, glucose has 6 Sugars differ in number of carbons, location of double bonds, and hydroxide groups.

9. More monosaccharides

10. Formation of a disaccharide

11. Breaking of a Disaccharide • What is this process called? • Why is water necessary for this reaction? • Is this reaction the same for other types of bio-molecules?

13. Starch and Cellulose • Starch is used as an energy storage molecule in plants • Cellulose is used for structural support creating the cell wall of plants • Both are polysaccharides

15. Look in the Book! • Find two polysaccharides used by animals and state their name and functions.

16. Lipids • Includes triglycerides, steroids, phospholipids • Lipids are defined as non-polar molecules • They don’t dissolve in water • Tend to coalesce (stick together) when placed in an aqueous solution • Function as energy storage, membranes, and hormones

17. Some types of lipids

18. Triglycerides: also known as FAT • A molecule used to store energy • Energy is stored as potential energy within chemical bonds • Made up of two parts • glycerol molecule • three fatty acids

19. Glycerol • a 3-carbon molecule • Fatty acid chains attach here

20. Fatty Acid: long non-polar chains of carbon

21. Glycerol + Fatty acid = Triglyceride

22. Phospholipid • Primary molecule used to create membranes • Typically found in bi-layers • Consists of a polar ‘head’ region, a glycerol neck, and a non-polar fatty acid ‘tail’ • Head region is hydrophilic – likes water • Tail region is hydrophobic – fears water

23. Phospholipid structure

24. Phospholipid Bi-layer • Non-polar, hydrophobic tails turn inward • Polar, hydrophilic heads point outward • This creates a membrane that can separate two environments

25. Cell Membrane

26. Steroids • Multiple ring shaped molecules • Function to increase or decrease fluidity of membranes, depending upon temperature. • Also used as hormones, chemical messengers sent through the blood stream

27. Common Steroids

28. Proteins • Proteins are polymers of amino acids • They have more functions than all other bio-molecules combined • They can be used for catalyzing reactions, structural support, chemical messengers, and much more. • If you don’t understand proteins you don’t understand how life works.

29. Proteins cont’d • There are about 20 different types of amino acids used in most living organisms • But combining these monomers into long chains it is possible to create an immense variety of polypeptides (proteins) • The function of protein is determined by its shape, which is determined by its amino acid sequence, which is determined by a DNA sequence.

30. Amino Acids • Contains an amine group (NH2), a carboxyl group (COOH), and a side group (R) • The R-group is the variable part which distinguishes one amino acid from another

31. Peptide bonds are formed by condensation reactions

32. A di-peptide is a two amino acid molecule

33. Proteins have four levels of structure

34. Primary Structure • Primary structure is the actual amino acid sequence produced from the DNA code. • Peptide bonds are the only bonds involved in the primary structure of a proteins

35. Secondary Structure • Created by hydrogen bonding between the amino and carboxyl groups of the amino acid backbones • Results in two distinct structures • Alpha helix • Beta pleated sheet

36. Alpha Helix

37. Beta Pleated Sheet

38. Tertiary Structure • Bending and folding of protein chain based upon R-group interactions • Can be hydrogen bonds, ionic bonds, or covalent bonds

41. Quaternary Structure • The combination of 2 or more protein subunits to create a fully functional protein • A protein composed of two identical subunits is known as a dimer

42. The Effects of Temperature on proteins • High temperatures break hydrogen bonds • molecules have too much kinetic energy and do not remain still long enough to attract one another. • Protein subunits separate and unfold • Proteins lose their structure and thus cannot function • Known as denaturation

43. The Effects of pH on Proteins • Proteins function optimally at specific pH levels • Increasing or decreasing [H+] may alter protein function • Why do you think ion concentration effects protein function?

44. The effect of pH on the activity of enzymes