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BioChemistry

BioChemistry. Week 5 - 7 OAPB Dr. Thornton. Carbon ’ s Place in the Living World. Carbon is a central element to life Most biological molecules are built on a carbon framework. Glucose. Simple sugar Most important energy source for our bodies Contains several –OH groups.

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BioChemistry

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  1. BioChemistry Week 5 - 7 OAPB Dr. Thornton

  2. Carbon’s Place in the Living World • Carbon is a central element to life • Most biological molecules are built on a carbon framework.

  3. Glucose • Simple sugar • Most important energy source for our bodies • Contains several –OH groups Can you identify the C and the –OH?

  4. Why Is Carbon Central to Life? • The complexity of living things is facilitated by carbon’s linkage capacity. • Carbon has great bonding capacity due to its structure.

  5. Why Is Carbon Central to Life? Carbon’s outer shell has only four of the eight electrons necessary for maximum stability in most elements. Go to PAGE 43 in text + or -??

  6. Carbon Bonds

  7. Why Is Carbon Central to Life? Carbon atoms are thus able to form stable, covalent bonds with a wide variety of atoms, including other carbon atoms. BUILD THIS MOLECULE

  8. 3.2 Functional Groups

  9. Functional Groups Remember carbon is a central element to life because most biological molecules are built on a carbon framework Groups of atoms known as functional groups can give special properties to carbon-based molecules

  10. Functional Groups • For example, the addition of an –OH group to a hydrocarbon molecule always results in the formation of an alcohol. Ethanol Methanol DRAW THEIR FORMULAS Isopropal

  11. Little Activity Add 50ml of H2O to 50 ml of 95% Isopropyl Alcohol (C3H6OH) WHAT HAPPENED?

  12. Functional Groups Functional groups often impart an electrical charge or polarity onto molecules, thus affecting their bonding capacity. Functional Groups Structural Formula Found in Group fatty acids, amino acids Carboxyl (–COOH) Hydroxyl (–OH) alcohols, carbohydrates amino acids Amino (–NH2) Identify Charges and polar areas DNA, ATP Phosphate (–PO4)

  13. 3.3 Carbohydrates

  14. Carbohydrates Carbohydrates are formed from the building blocks or monomers of simple sugars, such as glucose.

  15. Carbohydrates These monomers can be linked to form larger carbohydrate polymers, which are known as polysaccharides or complex carbohydrates.

  16. Complex Carbohydrates Four polysaccharides are critical in the living world: • Starch (energy storage in plants) • Glycogen (stored energy in animals) • Cellulose (make-up of plant cell walls) • Chitin (make-up of exoskeletons)

  17. Four Complex Carbohydrates (1) Starch Structure Starch is the nutrient storage form of carbohydrates in plants. Function Serves as a form of carbohydrate storage in many plants Example Starch granules within cells of a rawpotato slice

  18. Four Complex Carbohydrates (2) Glycogen Glycogen is the nutrient storage form of carbohydrates in animals. Serves as a form ofcarbohydrate storage in animals Glycogen granules(black dots) withina liver cell

  19. Four Complex Carbohydrates (3) Cellulose Cellulose is a rigid, structural carbohydrate found in the cells walls of many organisms. Provides structuralsupport for plantsand other organisms Cellulose fibers within the cell wallof a marine algaecell

  20. Four Complex Carbohydrates (4) Chitin Chitin is a tough carbohydrate that forms the external skeleton of arthropods. Makes up a large portion of the outer “skin” or cuticle of arthropods The chitinous cuticleof a tick

  21. 3.4 Lipids

  22. Lipids The defining characteristic of all lipids is that they do not readily dissolve in water (think fats) Glycerin (pg 34 of text)

  23. Lipids Lipids do not possess the monomers-to-polymers structure seen in other biological molecules; no one structural element is common to all lipids (grrrrr)

  24. Lipids Among the most important lipids are the triglycerides, composed of a glyceride and three fatty acids. Most of the fats that human beings consume are triglycerides.

  25. The Triglyceride Tristearin fatty acids glycerol Figure 3.8

  26. Saturated Fatty Acids (Pg 51 of text)

  27. Monosaturated Fatty Acids

  28. Polyunsaturated Fatty Acids

  29. Phospholipids • A third class of lipids is the phospholipids • Each is composed of two fatty acids, glycerol, and a phosphate group.

  30. Phospholipids The material forming the outer membrane of cells is largely composed of phospholipids.

  31. Phospholipids (a) Phospholipid structure — glycerol phosphate group variable group nonpolar tails polar head (b) Phospholipid orientation “like attracts like” nonpolar hydrophobic tails (fatty acids) exposed to oil oil (nonpolar) polar hydrophilic heads exposed to water water (polar) Figure 3.12

  32. Waxes A fourth class of lipids is the waxes, each of which is composed of a single fatty acid linked to a long-chain alcohol

  33. Waxes • Waxes have an important “sealing” function in the living world. • Almost all plant surfaces exposed to air, for example, have a protective covering made largely of wax.

  34. Waxes Figure 3.13

  35. 3.5 Proteins

  36. Proteins • Proteins are an extremely diverse group of biological molecules composed of the monomers called amino acids.

  37. Proteins • Sequences of amino acids are strung together to produce polypeptide chains, which then fold up into working proteins. • Important groups of proteins include enzymes, which hasten chemical reactions, and structural proteins, which make up such structures as hair.

  38. Table 3.4 Types of Proteins Examples Role Type Enzymes Quicken chemical reactions Sucrase: Positions sucrose (table sugar) in such a way that it can be broken down into component parts of glucose and fructose. Growth hormone: Stimulates growth of bones Hormones Chemical messengers Move other molecules Transport Hemoglobin: Transports oxygen through blood Myosin and actin: Allow muscles to contract Contractile Movement Healing; defense against invader Protective Fibrinogen: Stops bleeding Antibodies: Combat microbial invaders Keratin: Hair, Collagen: Cartilage Structural Mechanical support Storage Stores nutrients Ovalbumin: Egg white, used as nutrient for embryos Toxins Bacterial diphtheria toxin Defense, predation Communication Glycoprotein: Receptors on cell surface Cell signaling Table 3.4

  39. Levels of Protein Structure • The primary structure of a protein is its amino acid sequence; this sequence determines a protein’s secondary structure—the form a protein assumes after having folded up.

  40. The linkage of several amino acids . . . A typical protein would consist of hundreds of amino acids . . . produces a polypeptide chain like this: Figure 3.16

  41. Levels of Protein Structure • The larger-scale three-dimensional shape that a protein assumes is its tertiary structure, and the way two or more polypeptide chains come together to form a protein results in that protein’s quaternary structure. • The activities of proteins are determined by their final folded shapes.

  42. Four Levels of Structure in Proteins (a) Primary structure The primary structure of any protein is simply its sequence of amino acids. This sequence determines everything else about the protein's final shape. amino acid sequence (b) Secondary structure Structural motifs, such as the corkscrew-like alpha helix, beta pleated sheets, and the less organized "random coils" are parts of many polypeptide chains, forming their secondary structure. alpha helix random coil beta pleated sheet (c) Tertiary structure folded polypeptide chain These motifs may persist through a set of larger-scale turns that make up the tertiary structure of the molecule. (d) Quaternary structure two or more polypeptide chains Several polypeptide chains may be linked together in a given protein, in this case hemoglobin, with their configuration forming its quaternary structure. Figure 3.18

  43. Lipoproteins • Lipoproteins are biological molecules that are combinations of lipids and proteins. • High-density and low-density lipoproteins (HDLs and LDLs, respectively), which transport cholesterol in human beings, are important determinants of human heart disease.

  44. Glycoproteins • Glycoproteins are combinations of carbohydrates and proteins. • The signal-receiving receptors found on cell surfaces often are glycoproteins.

  45. Proteins PLAY Animation 3.5: Proteins

  46. 3.6 Nucleic Acids

  47. Nucleic Acids • Nucleic acids are polymers composed of nucleotides.

  48. Nucleotides • The nucleic acid DNA (deoxyribonucleic acid) is composed of nucleotides that contain a sugar (deoxyribose), a phosphate group, and one of four nitrogen-containing bases.

  49. (a) Nucleotides are the building blocks of DNA. Nucleotide nitrogenous base sugar (deoxyribose) DNA consists of two strands of nucleotides linked by hydrogen bonds phosphate group (b) A computer-generated model of DNA The outer “rails” of the double helix are composed of sugar and phosphate components of the molecule The rungs consist of bases hydrogen- bonded together DNA double helix Figure 3.19

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