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Biochemistry of Cells

Biochemistry of Cells

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Biochemistry of Cells

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  1. Biochemistry of Cells

  2. What you need to learn… • Why carbon? • Name the 4 macromolecules • Know the building block or monomer of each. • Know their functions • Know examples of each. • Know what dehydration synthesis and hydrolysis are. • Understand some properties of these molecules

  3. About 60-90 percent of an organism is water Water Water is used in most reactions in the body Water is called the universal solvent

  4. Water Properties • Polarity Cohesiveness Adhesiveness

  5. The Water Molecule • Polarity • A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. • (+) (—)

  6. Hydrogen Bonds • Polar water molecules act like magnets and attract each other • Hydrogen Bonds • The attraction of the Hydrogen end (+) of one molecule for the Oxygen end (-) of another water molecule. • They are the strongest bonds that can form betweenmolecules

  7. Hydrogen Bonds

  8. Cohesion • The attraction between molecules of the same substance (e.g. water). • Allows some insects and spiders to walk on water.

  9. Adhesion • Attraction between molecules of different substances • Responsible for Capillary forces in plants

  10. Carbon-based Molecules • Although a cell is mostly water, the rest of the cell consists mostly of carbon-based molecules Organic chemistry is the study of carbon compounds

  11. Carbon is a Versatile Atom • It has four electrons in an outer shell that holds eight Carbon can share its electrons with other atoms to form up to four covalent bonds

  12. Carbon can use its bonds to:: • Attach to other carbons Form an endless diversity of carbon skeletons

  13. Shape of Organic Molecules • Each type of organic molecule has a unique three-dimensional shape The shape determines its function in an organism

  14. Giant Molecules - Polymers • Large molecules are called polymers Polymers are built from smaller molecules called monomers Biologists call them macromolecules

  15. Most Macromolecules are Polymers • Polymers are made by stringing together many smaller molecules called monomers Nucleic Acid Monomer

  16. Linking Monomers Cells link monomers by a processcalled dehydration synthesis (removing a molecule of water) Remove H H2O Forms Remove OH This process joins two sugar monomers to make a double sugar

  17. Breaking Down Polymers • Cells break down macromolecules by a process called hydrolysis (adding a molecule of water) Water added to split a double sugar

  18. Macromolecules in Organisms • There are four categories of large molecules in cells: Carbohydrates Lipids Proteins Nucleic Acids

  19. Monosaccharides: • Called simple sugars Include glucose, fructose, & galactose Have the same chemical, but different structural formulas called an isomer. C6H12O6

  20. Monosaccharides • Glucose is found in sports drinks Fructose is found in fruits Honey contains both glucose & fructose Galactose is called “milk sugar”

  21. Carbohydrates • Carbohydrates include: • Small sugar molecules in soft drinks • Long starch molecules in pasta and potatoes

  22. Rings • In aqueous (watery) solutions, monosaccharides form ring structures

  23. Cellular Fuel • Monosaccharides are the main fuel that cells use for cellular work ATP

  24. Disaccharides • A disaccharide is a double sugar They’re made by joining two monosaccharides Involves removing a water molecule (dehydration)

  25. Disaccharides • Common disaccharides include: • Sucrose (table sugar) • Lactose (Milk Sugar) • Maltose (Grain sugar)

  26. Polysaccharides • Complex carbohydrates Composed of many sugar monomers linked together Polymers of monosaccharide chains

  27. Examples of Polysaccharides Glucose Monomer Starch Glycogen Cellulose

  28. Sugars in Water • Simple sugars and double sugars dissolve readily in water WATER MOLECULE They are hydrophilic, or “water-loving” SUGAR MOLECULE

  29. Lipids • Lipids are hydrophobic –”water fearing” Do NOT mix with water Includes fats, waxes, steroids, & oils FAT MOLECULE

  30. Function of Lipids • Fats store energy, help to insulate the body, and cushion and protect organs

  31. Types of Fatty Acids • Unsaturated fatty acids have less than the maximum number of hydrogens bonded to the carbons (a double bond between carbons) Saturated fatty acids have the maximum number of hydrogens bonded to the carbons (all single bonds between carbons)

  32. Types of Fatty Acids Single Bonds in Carbon chain Double bond in carbon chain

  33. Triglyceride • Monomer of lipids Composed of Glycerol & 3 fatty acid chains Glycerol forms the “backbone” of the fat Organic Alcohol

  34. Triglyceride Fatty Acid Chains Glycerol

  35. Fats in Organisms • Most animal fats have a high proportion of saturated fatty acids & exist as solids at room temperature (butter, margarine, shortening)

  36. Fats in Organisms • Most plant oils tend to be low in saturated fatty acids & exist as liquids at room temperature (oils)

  37. Steroids • The carbon skeleton of steroids is bent to form 4 fused rings Cholesterol Cholesterol is the “base steroid” from which your body produces other steroids Estrogen Testosterone Estrogen & testosterone are also steroids

  38. Synthetic Anabolic Steroids • They are variants of testosterone Some athletes use them to build up their muscles quickly They can pose serious health risks

  39. Proteins • Proteins are polymers made of monomers called amino acids All proteins are made of 20 different amino acids linked in different orders Proteins are used to build cells, act as hormones & enzymes, and do much of the work in a cell

  40. Four Types of Proteins Storage Structural Contractile Transport

  41. 20 Amino Acid Monomers

  42. Linking Amino Acids Carboxyl • Cells link amino acids together to make proteins Amino Side Group The process is called dehydration synthesis Dehydration Synthesis Peptide bonds form to hold the amino acids together Peptide Bond

  43. Proteins as Enzymes • Many proteins act as biological catalysts or enzymes Thousands of different enzymes exist in the body Enzymes control the rate of chemical reactions by weakening bonds, thus lowering the amount of activation energy needed for the reaction

  44. Protein Structures • Secondary protein structures occur when protein chains coil or fold When protein chains called polypeptides join together, the tertiary structure forms In the watery environment of a cell, proteins become globular in their quaternary structure

  45. Denaturating Proteins Changes in temperature & pH can denature (unfold) a protein so it no longer works Cooking denatures protein in eggs Milk protein separates into curds & whey when it denatures

  46. Nucleic Acids • Store hereditary information Contain information for making all the body’s proteins Two types exist --- DNA & RNA

  47. Nucleic Acids Nitrogenous base (A,G,C, or T) Nucleic acids are polymers of nucleotides Phosphate group Thymine (T) Sugar (deoxyribose) Phosphate Base Sugar Nucleotide

  48. Bases • Each DNA nucleotide has one of the following bases: Thymine (T) Cytosine (C) • Adenine (A) • Guanine (G) • Thymine (T) • Cytosine (C) Adenine (A) Guanine (G)

  49. End