Understanding Biomolecules: Structure, Function, and Importance in Cells

1. The Chemistry of Life - Biochemistry Ch 15

2. Biomolecules • Biomolecules are molecules produced and used within a cell • Cells are the most basic unit of most living things

3. Cell Components • Both plant and animal cells have many features in common

4. Plasma membrane – this is the boundary of the cell. It also regulates the movement of particles in and out of the cell. • For animal cells this is the outer most layer • Plant cells have a cell wall outside the plasma membrane

5. Both plant and animal cells have a nucleus • This contains the DNA which is the genetic code and tells the cell what to do

6. Between the nucleus and the plasma membrane is a thick liquid called cytoplasm • The cytoplasm is where all of the other components of the cell are found

7. Organelles are the small components found within the cytoplasm • Each organelle has a specific function that it must carry out in order for the cell to function

8. Plant Cell

9. Animal Cell

10. Biomolecules • Organelles produce, store, or transport biomolecules • The most common biomolecules are: • Carbohydrates • Lipids • Proteins • Nucleic acids

11. Carbohydrates • Carbohydrates are molecules composed of carbon, hydrogen, and oxygen • Plants produce carbohydrates during photosynthesis by combining carbon dioxide with water, hence the name.

12. Saccharide • Saccharide is another way to say carbohydrate • Saccharides can be mono-, di-, or poly-

13. Mono- • A monosaccharide is the basic building block of complex carbohydrates • So a monosaccharide is the same as a monomer

14. C6H12O6 • Simple Sugars

15. Di- • Disaccharides are composed of two monosaccharides joined together • Your body metabolizes these into their monosaccharide forms

16. Table sugar

17. Lactose

18. Intolerance to lactose • Why are people lactose intolerant? • Lactase is the enzyme that breaks down lactose • As we age we start to produce less and less lactase

19. Solutions • Add lactase to milk or take it just before eating dairy products • Acidophilus bifudus kills the bacteria in the intestines that breakdown lactose

20. Table 15-1, p. 298

21. p. 298

22. p. 298

23. p. 298

24. Simple? • Monosaccharides and disaccharides are called “simple carbohydrates” because they are made of only one or two monosaccharides

25. Polysaccharides • Polysaccharides are long chains of monosaccharides much like polymers are long chains of monomers

26. Polysaccharides therefore can be called “complex carbohydrates” since they have more than 2 monosaccharides joined together

27. Different types of monosaccharides can be joined together to form many different functioning polysaccharides

28. Joint lubricant

29. Exoskeletons

30. Glucose based polysaccharides • For humans, the only polysaccharides we consume are all made from glucose • There are 3 types • Starch • Glycogen • Cellulose

31. Starch • Plants produce glucose during the process of photosynthesis • Glucose is the fuel of the plant cell, and us as well • So excess glucose must be stored

32. Thus plants store the glucose as starch • Plant starch has two forms • Amylose • Amylopectin

33. Amylose • Amylose is a straight chain of glucose that coils around itself • This leaves only two ends open for release of glucose

34. Amylopectin • Amylopectin is also coiled like amylose but it branches every so often making it more bulky and having more free ends open to release glucose.

36. Glycogen • Animals store glucose as glycogen • A.K.A. animal starch

37. Glycogen resembles amylopectin • However it is more branched than amylopectin

38. Glycogen is most abundant in the muscles and liver • Why would glycogen be stored in muscles?

40. Cellulose • The third type of glucose polymer is cellulose • Plants use cellulose to form their cell wall

41. Cellulose is different from starch and glycogen • Cellulose makes long straight chains of glucose which can hydrogen bond and thus are very strong

42. Isomers • The main difference is the type of glucose used • Starch and glycogen use an α-link • Cellulose uses a β-link

43. These two types of linkages are due to the presence of isomers of glucose • In α-linked glucose both of the hydroxyl groups are on the bottom of the ring • In β-linked glucose one hydroxyl is above the ring and the other is below the ring

44. Because cellulose uses a β linkage it forms a straight chain and does not coil • This type of linkage also makes it where we can not digest cellulose

46. Termites eat wood, so can they break a β linkage between glucose molecules?

47. So glucose is the energy unit of the cell • When stored as starch it can be used to provide energy when needed • When stored as cellulose it loses its energy providing ability but serves a structural role instead

48. Lipids

49. Lipids • - have many functions and diverse structures • One thing in common…insoluble in water

50. Two basic classes are fats and steriods • Fats are both synthesized and obtained from diet (95% of our lipid intake) • Steroids are produced by the body or synthetically (5% of our total lipid intake)