Chapter 2 The Chemistry of Life

Transcription

1 Chapter 2 The Chemistry of Life

2 I. Water Liquid Naturally occurring It expands liquid to solid Covers more than 75% of our surface Most abundant in living organisms most important inorganic compound for living organisms

3 Properties of Water Due to an uneven distribution of electrons it is charged on each end (like a magnet), so it is a polar molecule Cohesion attraction between molecules of the same substance - water molecules cling to other water molecules(hydrogen bonding-which is a weak attraction between H bond and another) - helps the transport of water against gravity in plants - produces surface tension Adhesion attraction between molecules of different substances - water molecules cling to other molecules meniscus in a graduated cylinder

4 Heat Capacity water can absorb or release a great deal of heat energy before changing temperature - protects organisms from overheating and freezing

5 Versatility as a Solvent Water is good at forming mixtures -due to its polarity, which allows it to form hydrogen bonds easily. -water can dissolve ionic compounds, and nonionic polar molecules. -large polar molecules (such as proteins) can dissolve in water if they have ionic and polar regions. Hydrophilic substance- has an affinity to water - water loving Hydrophobic substance- does not have an affinity to water - water hating

6 Mixtures A substance composed of two or more elements or compounds mixed but not chemically combined ex: salt and pepper Can add different amounts ex: Earth s atmosphere Types: solution, suspension, colloid

7 Solution A mixture in which one or more substances are distributed into another substance Solute substance being dissolved Solvent substance that does the dissolving ex: H20 universal solvent dissolves almost anything The concentration of a solution is a measurement of the amount of solute dissolved in a fixed amount of solution Aqueous solutions solutions in which water is the solvent

8 Types of Solutions 1. Saturated solute = solvent 2. Unsaturated solute < solvent 3. Supersaturated solute > solvent

9 Suspension A mixture in which particles spread through a liquid or a gas, but settle out over time ex:starch and water Heterogeneous large particles, visibly different substances or phases

10 Colloid Particles do not settle out over time Homogeneous solution same uniform appearance and composition throughout Phases: Sol liquid Cytoplasm Gel semi-solid Types: Reversible sol gel sol gel etc. ex: jello Irreversible sol gel ex: egg white ( albumen )

11 Compounds vs. Mixtures H2O 1. Chemical union of 2 or more different elements 2.Elements in definite amounts 3. Chemical separation Sand and gravel 1. Physical union of 2 or more different elements 2. Elements indefinite amounts 3. Physical separation

12 Acids Compounds that release hydrogen ions into solution HCl H+ + Cl They have a sour taste

13 Bases Alkaline Compounds that release hydroxide ( OH ) ions into solution NaOH Na + + OH They have a bitter taste

14 Neutralization Reaction Chemical reaction that occurs when ( H ) ions of a strong acid react with the ( OH ) ions of a strong base to form water H + + OH H2O

15 ph Scale ranges from 0 to Acid 8 14 Base 7 neutral

16 Energy The ability to do work (movement of a mass) Can be converted from one form to another Kinetic energy of motion energy is available to do work and causes changes Potential energy at rest, stored energy that is available to do work, but work or change is not taking place

17 Chemical Reactions The process of breaking chemical bonds or of forming new bonds or both Chemical Equation Shows the products and reactants of a chemical reaction Ex: 2 H2O 2 H reactant product

18 II. Chemical Compounds in Living Things 114 elements 92 natural C H O N 96.3% body weight Organic compounds contain carbon Inorganic compounds - do not contain carbon - exception is CO2

19 Carbon - unique element forms covalent bonds that are strong and stable - bond easily with other elements - form unlimited length of chains bond to other C atoms

20 Polymerization - process by which large compounds are constructed by joining smaller compounds - Monomers smaller compounds joined together by chemical bonds to form polymers - many polymers are so large that they are called macromolecules

21 III. Compounds of Life Four Groups of Organic Compounds 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids

22 1. Carbohydrates C H O 1:2:1 ratio Sugar molecules Main source of energy ( humans )

23 Monosaccharides Simple sugar Glucose ( from green plants) Galactose ( milk ) Fructose ( found in fruits sweetest ) C6 H12 06 The arrangement of atoms makes them different

24 Dehydration Synthesis Reaction in which small molecules join to form a large molecule, removing water in the process Compound formed from the joining of 2 single sugars in the dehyd.syn. is a disaccharide

25 Double sugar C12 H22 O11 Sucrose ( table sugar) Maltose Lactose Disaccharide

26 Polysaccharide Large molecule formed when many monosaccharides link together Starch many glucose molecules Glycogen is an animal starch found in many liver and muscle cells Cellulose found only in plants

27 Hydrolysis Water splitting Reverse reaction Polysaccharides split apart again to form monosaccharides

28 2. Lipids Organic compounds that are waxy or oily Store energy Form membranes Chemical messengers Fats, Waxes and Oils Solid Liquid Fatty acids are long chains of H and C atoms with a carboxyl ( COOH ) group at one end Glycerol is an organic alcohol that contains 3 C atoms, each attached to a hydroxyl ( OH ) group

29 Many lipids form by the attachment of 2 or 3 fatty acids to glycerol Saturated Lipids contain maximum # of hydrogen atoms if every C atom in a fatty acid chain is joined to another C atom by a single bond

30 Unsaturated Lipids if a pair of C atoms is joined by a double bond Polyunsaturated Lipids if a fatty acid contains several double bonds - liquid at room temp. and are used in many cooking oils Kinds of Fats 1. triglycerides 1 glycerol, 3 fatty acids ( most common in the body)

31 2.Phospholipids - 1 glycerol, 2 fatty acids, 1 phosphate and nitrogen - Molecules consisting of parts that dissolve well in water and parts that do not ( oily ) - When mixed with water they form liposomes - Each is formed from a double layer of lipid molecules which helps to form cell membranes 3.Sphingolipids alcohol base instead of glycerol base - protects nervous pads called mylein 4.Sterols - most common cholesterol compound found in animal fats, meats and dairy products that can build cells, but in excess can be a risk factor in heart disease

32 3. Protein Contain C H O N Polymers of amino acids Amino group NH2 Carboxyl group COOH 20 different kinds Differ in the R groups Make up all your parts Regulate all body processes by making enzymes or hormones Control what passes in and out of your cells Protect you from disease Carry O2 to all parts of body - hemoglobin

33 Peptide bond covalent bond that joins two amino acids - a molecule of water is lost (dehydration) - dipeptide 2 a. a. - tripeptide 3 a. a. - polypeptide long chain of a.a.

34 Enzymes One of a number of special proteins A biological catalyst that lowers the activation energy of reaction in cells Catalyst speeds up a chemical reaction Specific A cell could have as many as 2,000 different enzymes (different reactions) Substrate reactants that are affected by an enzyme They bind to an enzyme at the active site The fit between an enzyme s active site and it s substrate is compared to a lock and key

35 Enzymes release energy, transfer information, assist in digestion, respiration, reproduction, vision, movement and thought

36 4. Nucleic Acids Large complex organic molecules that are composed of CHON and P They are polymers of individual monomers called nucleotides Nucleotides composed of and built up from three basic parts 5C sugar, a phosphate group and a nitrogenous base Individual nucleotides can be linked together by covalent bonds to form a polynucleotide

37 Two types of Nucleic Acids DNA and RNA They differ in the type of sugar: deoxyribose/ribose Despite the name they are not strong acids They store and transmit genetic energy