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Biology - Chapter 4 “ The Chemical Basis of Life”

Biology - Chapter 4 “ The Chemical Basis of Life”. Charles Page High School Stephen L. Cotton. Section 4.1 Water. Objectives: List some important properties of water. Section 4.1 Water. Objectives: Describe the nature of mixtures, solutions, and suspensions. Section 4.1 Water.

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Biology - Chapter 4 “ The Chemical Basis of Life”

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  1. Biology - Chapter 4“The Chemical Basis of Life” Charles Page High School Stephen L. Cotton

  2. Section 4.1Water • Objectives: • List some important properties of water.

  3. Section 4.1Water • Objectives: • Describe the nature of mixtures, solutions, and suspensions.

  4. Section 4.1Water • Objectives: • Define acids, bases, neutralization, and pH scale.

  5. Section 4.1Water • Water- is quite common, but has many unique characteristics • One of few compounds that is liquid • expands as it turns to solid • explains why ice floats: it is less dense than the liquid stage • important to fish and plants

  6. Section 4.1Water • Covers more than 75% of earth • Most abundant compound in nearly all living organisms • Most important property: • uneven distribution of electrons, thus slightly charged on each end, like a little magnet; polar Fig. 4-2, page 64 • attracted to other water & particles

  7. Section 4.1Water • Water is a good solvent because of it’s polarity (attracted to other items) • Mixtures: composed of two or more materials that are mixed, but not chemically combined • salt & pepper; sugar & sand; air; soil • can be mixed in varying amounts • 2 types: 1) solutions & 2) suspensions

  8. Section 4.1Water • Solutions: example is sugar water • homogeneous; variable composition • Made of solvent- substance that does the dissolving (water) and solute- the substance that is dissolved (sugar) • water called the “universal solvent”, and due to it’s polarity Fig. 4-4, p. 65

  9. Section 4.1Water • Acids: • Acids are ionically bonded compounds that break apart when dissolved in water to produce hydrogen ions • NaCl  Na1+ + Cl1- • compound = ion + ion • HCl  H1+ + Cl1- • hydrochloric acid = hydrogen ion + chloride ion (notice that this is a type of acid, because it produces hydrogen ions) Thus, NaCl is not a type of acid.

  10. Section 4.1Water • The hydrogen ion (H1+) is the most chemically reactive ion known • compounds that release the hydrogen ion are called Acids • Bases release hydroxide ion (OH1-) • NaOH  Na1+ + OH1- • acids and bases are dangerous; they can break other chemical bonds

  11. Section 4.1Water • Neutralization and pH: • Strong acid + strong base results in the H1+ and OH1- reacting together to form water, H2O • called a neutralization reaction • may not be perfectly neutral, unless the correct amount of each is used

  12. Section 4.1Water • A measurement system known as the pH scale indicates the relative amount of H1+ and OH1- • pH scale ranges from 0 to 14 • pure water = 7.0 • less than 7.0 = acids • greater than 7.0 = bases • Fig. 4-6, page 66 for examples

  13. Section 4.1Water • Suspensions: are heterogeneous • do not break into individual particles, but are still small enough that they may or may not settle • sand and water will settle • blood- contains dissolved materials, clotting materials, living cells, others- will not settle

  14. Section 4.2Chemical Compounds in Living Things • Objectives: • Identify the four most abundant elements in living things.

  15. Section 4.2Chemical Compounds in Living Things • Objectives: • Compare inorganic compounds and organic compounds.

  16. Section 4.2Chemical Compounds in Living Things • Objectives: • Describe the properties that make carbon unique.

  17. Section 4.2Chemical Compounds in Living Things • Objectives: • Explain the importance of polymerization.

  18. Section 4.2Chemical Compounds in Living Things • About 90 naturally occurring elements; only 11 common in living organisms • Four make up over 96% of the human body: C, N, O, and H • Two major groups of chemicals: 1) organic and 2) inorganic

  19. Section 4.2Chemical Compounds in Living Things • Inorganic Compounds: • usually, those chemicals that do not contain the element carbon • carbon dioxide is an exception • others: water, calcium phosphate, salts, minerals in soil and sand

  20. Section 4.2Chemical Compounds in Living Things • Organic Compounds: • carbon-containing compounds • more than 2 million of them. Why? • Carbon forms covalent bonds that are strong and stable. • Can form 4 bonds- with itself as well as other elements

  21. Section 4.2Chemical Compounds in Living Things • Fig. 4-8, page 68 • Simplest organic compound is methane, CH4 (natural gas) • carbon can form long chains by bonding with other carbon • single-, double-, and triple-bonds are possible; also rings Fig. 4-9, p.69 • no other element can do this!

  22. Section 4.2Chemical Compounds in Living Things • Polymerization: • process in which large compounds (called polymers) are constructed by joining together many smaller compounds (called monomers) • joined much like the letters of the alphabet can form larger words • Fig. 4-10, page 69

  23. Section 4.3Compounds of Life • Objectives: • Identify the four groups of organic compounds found in living things.

  24. Section 4.3Compounds of Life • Objectives: • Describe the structure and function of each group of compounds of life.

  25. Section 4.3Compounds of Life • Objectives: • Explain how enzymes work and why they are important to living things.

  26. Section 4.3Compounds of Life • 4 groups of organic compounds found in living things: 1) Carbohydrates 2) Lipids 3) Proteins 4) Nucleic Acids

  27. Section 4.3Compounds of Life 1. Carbohydrates: • includes sugars and starches (polymer) • contain the elements C, H, and O, with the ratio 1:2:1 (carbo- -hydrate) • simplest called monosaccharides (monomers), or simple sugars- examples are glucose, galactose, and fructose

  28. Section 4.3Compounds of Life • Glucose- made by green plants • Galactose- found in milk • Fructose- found in fruits; sweetest of these 3 (none of which is very sweet) • all have the same formula: C6H12O6 • have a different arrangement of these atoms-”isomers” Fig. 4-11, p.70

  29. Section 4.3Compounds of Life • Sugars are used for fuel, containing a large amount of energy stored in their chemical bonds • Most organisms use glucose as fuel • Dehydration Synthesis- joins 2 simple sugars by losing 1 water Fig. 4-12, p.71 • monosaccharide + monosaccharide = disaccharide + water

  30. Section 4.3Compounds of Life • Sucrose (table sugar) made from glucose + fructose • Maltose (malt sugar) made from glucose + glucose • Lactose (milk sugar) made from glucose + galactose • All 3 disaccharides are: C12H22O11

  31. Section 4.3Compounds of Life • Polysaccharides: • large molecules, formed by many monosaccharide units together • used to store excess sugar in the form of starch (plants) or glycogen (animal starch) • Cellulose (wood)- gives plants strength and rigidity. Can we digest it?

  32. Section 4.3Compounds of Life • Hydrolysis: • reverse of dehydration synthesis, used to break polysaccharides into monosaccharides • water is added back to the molecules • Fig. 4-14, page 72

  33. Section 4.3Compounds of Life 2. Lipids: • also called fats & waxes (solids), and oils (liquids at room temp.) • 3 major roles in living organisms: 1. Can be used to store excess energy 2. Form biological membranes 3. Used as chemical messengers

  34. Section 4.3Compounds of Life • Lipids (polymer) formed by monomers: • fatty acids and glycerol Fig. 4-16, p.73 • fatty acids have a carboxyl group that contains: 1 C, 1 H, and 2 O (-COOH) • glycerol is an organic alcohol, with 3 C each attached to a hydroxyl group (-OH) • Usually 2 or 3 fatty acids + 1 glycerol, joined by what method? (Dehydration synthesis)

  35. Section 4.3Compounds of Life • Saturated and Unsaturated Lipids: • Saturated- has only single bonds, thus contains maximum # of H • not very healthy; hard to break down • common in meats and dairy products • usually solids- found in bacon, sausage, butter, milk, steak

  36. Section 4.3Compounds of Life • Unsaturated- if the carbons are linked by double bonds; does not contain the maximum # of H • Having several double bonds is called polyunsaturated • tend to be liquids- used in cooking, such as sesame, peanut, corn oil

  37. Section 4.3Compounds of Life • Both plants and animals can use lipids to store energy • lipids have less O than carbohydrates, thus less mass per unit of energy • Carbohydrates release: 4 calories/gram • Lipids release: 9 calories/gram • Much more energy from an equal amount of lipid than carbohydrate

  38. Section 4.3Compounds of Life • Sterols and Phospholipids: • These are two other types of lipids • An important sterol: cholesterol- is important, but not in excess; help build cells and carry messages • Phospholipids- have a part that does dissolve well in water, and a part that does not dissolve well

  39. Section 4.3Compounds of Life • When phospholipids are mixed with water, a liposome is formed, which has a double layer • this helps them form cell membranes

  40. Section 4.3Compounds of Life 3. Proteins (a polymer) formed by the monomer: amino acids • contain C, H, O, and also Nitrogen • Fig. 4-19, page 74 • amino acids have an amino group (-NH2) as well as the carboxyl group (-COOH)

  41. Section 4.3Compounds of Life • More than 20 different amino acids, have a different location of the R group (R = the hydrocarbon part) • Peptides- a peptide bond joins two amino acids (by what process?) • Fig. 4-20, page 75 • dipeptide- 2 amino acids; tri- has 3 • polypeptide- long chain joined

  42. Section 4.3Compounds of Life • Protein structure: made of one or more polypeptide chains • Uses: 1. Help carry out chemical reactions 2. Pump molecules in or out of cell 3. Responsible for cell movement 4. Structural components

  43. Section 4.3Compounds of Life • Enzymes: • Life is possible because of chemical processes • A catalyst will speed up the rate of a chemical reaction, without being used up itself • work by lowering the “start-up” energy of a reaction

  44. Section 4.3Compounds of Life • Biological catalysts are called enzymes; usually a type of protein • enzymes speed up a reaction by binding to the reactants (called substrates) at the region known as the active site • Very specific, like a lock and key • Fig. 4-22, page 76

  45. Section 4.3Compounds of Life 4. Nucleic acids (polymer): • large, complex molecules composed of C, O, H, N, and Phosphorus • the monomer forming them is called a nucleotide

  46. Section 4.3Compounds of Life • Nucleotides are made of: 1. A special 5-carbon sugar 2. A phosphate group 3. A nitrogenous base • Fig. 4-23, page 76

  47. Section 4.3Compounds of Life • Two types of Nucleic Acids: 1. RNA (ribonucleic acid) - contain the sugar “ribose” 2. DNA (deoxyribonucleic acid) - contain the sugar “deoxyribose” • Neither are strongly acidic • Why? Acids that have C are usually not strong • Function: to store and transmit the genetic information for life itself

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