UNIT 3 CHAPTER 2 Biochemistry

1. BIOLOGY UNIT 3 CHAPTER 2 Biochemistry

2. CHAPTER 2 SECTION 1 Basic Chemistry

3. Basics of Chemistry • A cellis made up of atoms, elements, compounds, and molecules. The chemical processes of an organism takes place inside the organism’s individual cells. Living and nonliving things are made up of tiny units called atoms.

4. Elements • An element cannot be broken down into any other substance or matter. • Pure silver (Ag) is an element. • It is made up of only silver atoms. • When you break down a silver atom, you get subatomic particles of electrons, protons, and neutrons.

5. Most Common Elements

6. Compounds • A compoundis formed when two or more elements combine chemically.

7. Compound Properties • The properties (or characteristics) of compounds are quite different from the properties of the elements from which they are composed. • For example, table sugar (sucrose) is made up of the elements carbon, hydrogen, and oxygen. • Carbon is a black solid, and hydrogen and oxygen are colorless gases. • However, when they combine chemically, they form a white granular substance.

8. Molecules • A molecule of a particular compound is made up of definite numbers and kinds of atoms bonded, or joined, together. • A molecule of water contains two hydrogen atoms and one oxygen atom bonded together (H20). • Two atoms of hydrogen bond together to form a molecule of hydrogen (H2).

9. Molecules and Compounds • When two or more atoms of the same element combine, the resulting substance is called a molecule of that element. • When two oxygen atoms combine they for a molecule of oxygen gas (O2). • When two or more different kinds of atoms bind, they form molecules of a compound. • Two hydrogen atoms combine with one oxygen atom to form the compound water (H2O).

10. Chemical Bonding • Chemical bonding is the process by which elements combine to form compounds. • The formation of a chemical bond can be • 1.) an ionic bond whichinvolves the transfer of electrons from one atom to another, or • 2.) a covalent bond whichinvolvesthe sharing of electronsbetween atoms.

11. Types of Chemical Bonds The basic types of chemical bonds are: • ionic bonds -- involve a transfer of electrons usually between molecules that have opposite charges • covalent bonds – involve molecules that share electrons • hydrogen bonds – aweak bond between polar molecules • peptide bonds – a type of bond that joins amino acids together to make a protein molecule

12. Chemical Bonding

13. Ionic Bonds • Anionic bond is a chemical bond formed when atomslose or gain electrons. • Sodium chloride (NaCl) is an example of an ionic compound held together by ionic bonds. Sodium loses one electron to chlorine when the bonding process occurs. Ionic bonds usually form between a metal (+) and a nonmetal (-).

14. Covalent Bonds • Covalent bonds are formed when atoms produce compounds by sharing electrons. • When making hydrogen gas, one molecule of hydrogen gas is formed when two hydrogen atoms join by sharing electrons (H2). • Covalent bonds usually form when nonmetals (-) share electrons.

15. Hydrogen Bonds and Polar Molecules • A hydrogen bond is a weakchemical attraction between polar molecules. • Polar molecules are molecules with an unequal distribution of electrical charge. • Water is an example of a polar molecule. • The partially positive end of one water molecule is attracted to the negative end of another water molecule. • The attraction between two water molecules is an example of a hydrogen bond, and is what holds water molecules together.

16. Peptide Bonds • Peptide bonds are a type of bond that joins amino acids together to make a protein molecule. • Polypeptides are formed from many amino acids bonded together. • Proteins are made up of long polypeptide chains.

17. CHAPTER 2 SECTION 2 WATER AND SOLUTIONS

18. Cohesion andSurface Tension • Cohesion is an attraction between substances of the same kind. • Because of cohesion, water and other liquids form thin films and drops. • Surface tension is a condition that occurs when molecules at the surface of water are linked together (cohesively)by hydrogen bonds, and prevent the surface of water from stretching or breaking easily.

19. Because of cohesion, water and other liquids form thin films and drops.

21. Surface tension prevents the surface of water from stretching or breaking easily. Once the surface tension is broken, the objects will sink.

22. Adhesion and Capillary Action • Adhesion is an attraction between different substances. • Adhesion powers a process known as capillary action. • Capillary actionis a process where water molecules move upward through a narrow tube such as the stem of a plant. • The attraction of water to the walls of the tube sucks the water up more strongly than gravity pulls it down. • Water moves upward through a plant from roots to leaves through a combination of capillary action, cohesion, and other factors.

23. Water moves upward through a plant from roots to leaves through a combination of capillary action, cohesion, adhesion, and other factors.

24. Aqueous Solutions • A solution is a mixture in which one or more substances are evenly distributed in another substance. • A solution is made up of the solute and the solvent. • A solute is the substance that is dissolved in a solution. • The solvent is the substance that dissolves another to form a solution.

25. Aqueous Solutions • Water is often called the “universal solvent” because it dissolves so many substances. • Many important substances in the body have been dissolved in blood or other aqueous fluids. • The polarity of water enables many substances to dissolve in water.

26. Aqueous Solutions • Ionic compounds and polar molecules dissolve best in water. • Nonpolar molecules do not dissolve well in water. • When nonpolar substances, such as oil, are placed in water, the water molecules are more attracted to each other than to the nonpolar molecules. • This explains why oil clumps or beads in water.

27. ABOVE: Water on the hydrophobic surface of grass. Hydrophobic molecules tend to be non-polar and thus prefer other neutral molecules and nonpolar solvents.

28. Acids and Bases -- Acids • Acids are compounds that release hydrogen ions (H+)when dissolved in water. • Acids have a sour taste, can dissolve many metals, and turn litmus paper red. • Examples of acids in the body are hydrochloric acid (produced by stomach cells that aids digestion), acetic acid (vinegar), and carbonic acid (in sodas).

29. Acids and Bases -- Bases • Bases are compounds that reduce the concentration of hydrogen ions in a solution. • Many bases release hydroxide ions (OH-)when dissolved in water. • Bases are bitter and slippery and turn litmus paper blue. • Examples of common bases are baking soda, Milk of magnesia, ammonia, bleach, detergents, and most soaps.

30. The pH Scale • The pH scale measures whether a solution is acid, basic or neutral. • The scale runs from 0 to 14. • A pH of 7 indicates that the solution is neutral. This means that the solution is neither an acid nor a base.

31. The pH Scale The higher the pH number, the more strongly basic the solution. A pH above 7 indicates that the solution is basic. The lower the pH number, the more acidic the solution. A pH below 7 indicates that the solution is acidic.

32. The pH Scale • Each successive change of 1 pH unit represents a tenfold change in hydrogen-ion concentration. • A solution with a pH of 6 has 10 times as many hydrogen ions as a solution with a pH of 7. • A pH of 3 indicates a 10,000-fold (10 X 10 X 10 X 10) increase in hydrogen-ion concentration.

33. CHAPTER 2 SECTION 3 Chemistry of Cells

34. . Chemical Formulas • A chemical formula represents the chemical makeup of a compound. • It shows the numbers and kinds of atoms present in a compound. • It is a type of “shorthand” that scientists use. C6H12O6 = CCCCCCHHHHHHHHHHHHOOOOOO

35. Examples of Chemical Formulas • The chemical formula for sugar is C6H12O6 (glucose). • This means that in one molecule of sugar, there are six carbon atoms, twelve hydrogen atoms and six oxygen atoms. • H2O(water) • SO2(sulfur dioxide) • CO2(carbon dioxide) • CaCO3 (calcium carbonate) • C6H10O5 (cellulose)

36. Equations • Equations are used to describe chemical reactions. • Reactantsare the substances that start the reaction. • The reactants are placed on the left side of the equation. • Productsare the substances formed by the reaction. • The products are placed on the right side of the equation. • The arrow means “yields,” “to make,” or “to form”.

37. Equations • Reactions may be represented either by words or formulas. • The word equation for aerobic respiration is: SUGAR + OXYGEN  ENERGY + CARBON DIOXIDE + WATER • A chemical equationis an equation that uses formulas instead of words. • The chemical equation for aerobic respiration is: C6H12O6 + 6O2  ATP + 6CO2 + 6H2O

38. Organic and Inorganic Compounds • Living things are made up of inorganic and organic compounds. • Inorganic compounds are compounds that do not contain both carbon and hydrogen. • The principal inorganic compounds found in living things are: • water • salts • inorganic acids • inorganic bases

39. Organic Compounds • Organic compounds are compounds that contain both carbon and hydrogen. • The main classes of organic compounds (macromolecules) found in living things are: • 1. carbohydrates (CHO) • 2. lipids (CHO) • 3. proteins (CHON) • 4. nucleic acids (CHONP)

40. Monomers, Polymers, and Isomers • Organic compounds can be: • monomers: compounds made up of single units • polymers: compounds made up of many units joined together • isomers: compounds with the same molecular formula, but different structural formulas

41. 1. CARBOHYDRATES (CHO) • Carbohydrates are the main source of energy for cell activities. • Two main types of carbohydrates are sugars and starches. • Carbohydrates are made up of the elements carbon, hydrogen, and oxygen(CHO). • Generally, there are twice as many hydrogen atoms as oxygen atoms in carbohydrates (2:1 ratio).

42. Monosaccharides • The simplest carbohydrates are called monosaccharides,or simple sugars. • Monosaccharides are called the “building blocks” of carbohydrates, or the subunits of carbohydrates. • A common monosaccharide isglucose (C6H12O6). Fructose is another example of a monosaccharide sugar. • Glucose is the plant sugar formed during photosynthesis.

43. Disaccharides • A disaccharide sugar,or double sugar, is formed when two simple sugars combine. • Maltose(C12H22O11) is an example of a common disaccharide. • Maltose is formed when two glucose molecules chemically combine (glucose + glucose).

44. Disaccharides • Lactoseis a disaccharide sugar composed of glucose and galactose. • Sucroseis a disaccharide sugar composed of glucose andfructose. sucrose lactose

45. Polysaccharides • Polysaccharidesare long chains of monosaccharides (sugar molecules) bonded together. • Starchandcelluloseareimportant polysaccharides found primarily in plants. • Glycogen is an important polysaccharide found in animals.

46. Starch – the energy storage molecule • Starch, or amylum, is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. • Starchis the energy storage molecule for plants. • Starch is the most common carbohydrate in the human diet, and is contained in large amounts in such staple foods as potatoes, wheat, maize (corn), and rice.

47. Cellulose – the structural molecule • Cellulose is the structural component of the cell walls of green plants, and is a complex polysaccharide composed of glucose monomers. • Cellulose is the most common organic compound on Earth. • About 33% of all plant matter is cellulose (the cellulose content of cotton is 90% and that of wood is 40–50%).

48. Cellulose The chemical formula for cellulose is C6H10O5 and it consists of a linear chain of several hundred to over ten thousand glucose units.

49. Glycogen – short-term energy storage for animals • Glycogenis a polysaccharide that serves as short-term energy storage for animals. • Glycogen is made primarily by the liver and the muscles. • Muscle cell glycogen appears to function as an immediate reserve source of available glucose for muscle cells. • When it is needed for energy, glycogen is broken down and converted again to glucose.

50. 2. Lipids (CHO) • Lipids are insoluble organic compounds that contain the elements carbon, hydrogen, and oxygen (CHO). • Lipids include fats, oils, waxes, and sterols, and some fat-soluble vitamins. • Fatty acids and • glycerol are the • building blocks, • or subunits, of • lipids.