Biological Molecules Can Have Complicated Structures

1. Biological Molecules Can Have Complicated Structures DNA Protein

2. How complicated are living things? Even a bacterium is made up of at least 10,000 different kinds of molecules. But these fall into 4 classes of organic molecules.

3. 4 Kinds of Organic Molecules

4. Properties of organic molecules: • Carbon skeletons as backbones • Side chains bear functional groups that are chemically active • polymers: chains of subunits

5. Organic molecules are built around carbon skeletons

6. Functional Groupschemically active side branches

7. Organic molecules are polymers

8. Dehydration (Condensation) Synthesis - Polymer Elongation

9. Hydrolysis - Polymer Disassembly

10. Structures are built of large molecules which are built of small molecules

11. Carbohydrates • carbohydrates are sugar polymers • used for: • energy storage • structural features

12. Sugars are characterized by size, the kinds of functional groups and their position

13. Another example

14. Linear carbon chains often become cyclic

15. Synthesis and breakdown of carbohydrate polymers

16. Disaccharides

17. Polysaccharides

18. Polysaccharides held together by weak bonds are used for energy storage (e.g., starch), whereas those held together by strong bonds are used or structural purposes (e.g., cellulose)

19. Cellulose

20. Lipids • One end is hydrophilic, the other hydrophobic • Often polymers (few large instead of many small subunits, fatty acid derivatives) • Used for: • Energy storage, e.g., fats and oils • Chemical messengers (hormones) , e.g., steroids • Chemical defenses , e.g., terpenes • Membranes , e.g., phospholipids

21. Fatty Acids Note: carbon and hydrogen have similar electronegativities and will form non-polar covalent bonds

22. A simple lipid - triglyceride

23. Saturated fat

24. Unsaturated fat

25. other lipids: Terpene (citronellol) Prostaglandin (PGE) Steroid (cholesterol)

26. Phospholipid

27. Phospholipids function in membranes

28. Membranes - more than lipids Glycoproteins (proteins with carbohydrate antennae) Membrane (lipid bilayer) lipid monolayer proteins

29. membrane systems can be extensive nuclear envelope ribosomes golgi apparatus rough endoplasmic reticulum smooth endoplasmic reticulum

30. Proteins • Every protein = an unbranched chain of amino acids • Each kind of protein has a unique amino acid sequence • Each amino acid sequence confers a specific 3D shape • Each kind of protein is coded for by a single gene • Proteins have many functions

31. Amino acids - 20 kinds

32. Acidic and basic amino acids

33. Non-polar amino acids

34. Polar amino acids

35. Peptide bond formation The peptide bond is surrounded by two important charges + -

36. A short protein - 4 amino acids

37. four levels of protein structure primary secondary tertiary quartenary

38. Secondary Structure and Hydrogen Bonds

39. Quartenary Structure in Hemoglobin Quartenary structure: 4 proteins (chains)

40. Hemoglobin and Sickle Cell Anemia:a single amino acid substitution can make a big difference under oxygen stress MUTATION: valine replaces glutamate hemoglobin polymerizes, forming long rods that distort the cell

41. Four levels of protein structure

42. Proteins differ in their 3D shapes

43. 3D shapes have specific cavities on their surfacethese cavities allow “lock and key” fits with other molecules with which the protein interact

44. Enzymes Control Chemical Activity

45. Molecules are modified in pathways, in numerous small controlled steps

46. Biochemical Pathways

47. Catalysts Control Chemical Activity

48. What is the significance of complicated shapes?Numerous weak bonds among complementary complex surfaces allow molecular recognition and catalysis.

49. Nucleic Acids: RNA & DNA • Nucleic acid molecules consist of polynucleotide strands • DNA has two complementary strands, RNA has one strand • Both DNA & RNA can replicate and store information • Nucleotide sequences code for amino acid sequences …DNA genes code for RNA and protein structure • Like proteins, RNA is single stranded and can fold up into complex 3D shapes ….RNA catalysts are ribozymes

50. Nucleotides have three subunits P S B