Slide 0 Copyright © Elsevier Inc. All Rights Reserved. Chapter 2 Chemistry of Life

Slide 1 Copyright © Elsevier Inc. All Rights Reserved. Learning Objectives Define the terms atom, element, molecule, and compound. Describe the structure of an atom. Compare and contrast ionic and covalent types of chemical bonding. Distinguish between organic and inorganic chemical compounds.

Slide 2 Copyright © Elsevier Inc. All Rights Reserved. Learning Objectives (contd.) Discuss the chemical characteristics of water. Explain the concept of pH. Discuss the structure and function of the following types of organic molecules: carbohydrate, lipid, protein, and nucleic acid.

Slide 3 Copyright © Elsevier Inc. All Rights Reserved. Chapter 2 Lesson 2.1 Chapter 2 Lesson 2.1

Slide 4 Copyright © Elsevier Inc. All Rights Reserved. Levels of Chemical Organization Elements, molecules, and compounds Elementa pure substance; made up of only one kind of atom Moleculea group of atoms bound together to form a larger chemical unit Compoundsubstances whose molecules have more than one kind of element

Slide 5 Copyright © Elsevier Inc. All Rights Reserved. Important Elements in the Human Body

Slide 6 Copyright © Elsevier Inc. All Rights Reserved. Levels of Chemical Organization Atoms Nucleuscentral core of atom Protonpositively charged particle in nucleus Neutronnoncharged particle in nucleus Atomic numbernumber of protons in the nucleus; determines the type of atom

Slide 7 Copyright © Elsevier Inc. All Rights Reserved. A Model of the Atom

Slide 8 Copyright © Elsevier Inc. All Rights Reserved. Levels of Chemical Organization (contd.) Energy levelsregions surrounding atomic nucleus that contain electrons electronnegatively charged particle may contain up to two electrons in the level closest to the nucleus may contain up to eight electrons in the remaining levels energy increases with distance from the nucleus

Slide 9 Copyright © Elsevier Inc. All Rights Reserved. Chemical Bonding Chemical bonds form to make atoms more stable. Outermost energy level of each atom is full. Atoms may share electrons, or donate or borrow them to become stable.

Slide 10 Copyright © Elsevier Inc. All Rights Reserved. Chemical Bonding (contd.) Ionic bonds Ions form when an atom gains or loses electrons in its outer energy level to become stable. Positive ionhas lost electrons; indicated by superscript positive sign(s), as in Na + or Ca + Negative ionhas gained electrons; indicated by superscript negative sign(s), as in Cl –

Slide 11 Copyright © Elsevier Inc. All Rights Reserved. Chemical Bonding (contd.) Ionic bonds form when positive and negative ions attract each other because of electrical attraction. Electrolytemolecule that dissociates (breaks apart) in water to form individual ions; an ionic compound

Slide 12 Copyright © Elsevier Inc. All Rights Reserved. Ionic Bonding

Slide 13 Copyright © Elsevier Inc. All Rights Reserved. Chemical Bonding Covalent bonds Covalent bonds form when atoms that share their outer energy fill up and thus become stable. Covalent bonds do not ordinarily dissociate in water.

Slide 14 Copyright © Elsevier Inc. All Rights Reserved. Covalent Bonding

Slide 15 Copyright © Elsevier Inc. All Rights Reserved. Chapter 2 Lesson 2.2 Chapter 2 Lesson 2.2

Slide 16 Copyright © Elsevier Inc. All Rights Reserved. Inorganic Chemistry Organic molecules contain carbon–carbon covalent bonds and/or carbon-hydrogen covalent bonds; inorganic molecules do not. Examples of inorganic molecules: water and some acids, bases, and salts.

Slide 17 Copyright © Elsevier Inc. All Rights Reserved. Inorganic Chemistry (contd.) Water Water is a solvent (liquid into which solutes are dissolved), forming aqueous solutions in the body Water is involved in chemical reactions Dehydration synthesischemical reaction in which water is removed from small molecules so they can be strung together to form a larger molecule Hydrolysischemical reaction in which water is added to the subunits of a large molecule to break it apart into smaller molecules

Slide 18 Copyright © Elsevier Inc. All Rights Reserved. Water-Based Chemistry

Slide 19 Copyright © Elsevier Inc. All Rights Reserved. Acids, bases, and salts Water molecules dissociate to form equal amounts of H + (hydrogen ion) and OH – (hydroxide ion). Acidsubstance that shifts the H + /OH – balance in favor of H + ; opposite of base Basesubstance that shifts the H + /OH – balance against H + ; also known as an alkaline; opposite of acid

Slide 20 Copyright © Elsevier Inc. All Rights Reserved. Inorganic Chemistry pHmathematical expression of relative H+ concentration in an aqueous solution 7 is neutral (neither acid nor base) pH values above 7 are basic; pH values below 7 are acidic. Neutralization occurs when acids and bases mix and form salts. Buffers are chemical systems that absorb excess acids or bases and thus maintain a relatively stable pH.

Slide 21 Copyright © Elsevier Inc. All Rights Reserved. The pH Scale

Slide 22 Copyright © Elsevier Inc. All Rights Reserved. Chapter 2 Lesson 2.3 Chapter 2 Lesson 2.3

Slide 23 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry Carbohydratessugars and complex carbohydrates Contain carbon (C), hydrogen (H), oxygen (O) Made up of six carbon subunits called monosaccharides or single sugars (e.g., glucose) Disaccharidedouble sugar made up of two monosaccharide units (e.g., sucrose, lactose)

Slide 24 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) Polysaccharidecomplex carbohydrate made up of many monosaccharide units (e.g., glycogen made up of many glucose units) The function of carbohydrates is to store energy for later use.

Slide 25 Copyright © Elsevier Inc. All Rights Reserved. Carbohydrates

Slide 26 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) Lipidsfats and oils Trigylcerides Made up of one glycerol unit and three fatty acids Store energy for later use

Slide 27 Copyright © Elsevier Inc. All Rights Reserved. Triglyceride

Slide 28 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) Phospholipids Similar to triglyceride structure, except with only two fatty acids, and with a phosphorus- containing group attached to glycerol The head attracts water and the double tail repels water, thus forming stable double layers (bilayers) in water Form membranes of cells

Slide 29 Copyright © Elsevier Inc. All Rights Reserved. Phospholipids

Slide 30 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) Cholesterol Cholesterol molecules have a steroid structure made up of multiple rings. Cholesterol stabilizes the phospholipid tails in cellular membranes. It is converted into steroid hormones, such as estrogen, testosterone, and cortisone by the body.

Slide 31 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) Proteins very large molecules made up of amino acids held together in long folded chains by peptide bonds Structural proteins form structures of the body Collagen is a fibrous protein that holds many tissues together. Keratin forms tough waterproof fibers in the outer layer of the skin.

Slide 32 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) Functional proteins Participate in chemical processes (examples: hormones, cell membrane channels and receptors, enzymes) Enzymes o Catalysts help chemical reactions occur. o Lock-and-keyeach enzyme fits a particular molecule that it acts on as a key fits into a lock Proteins can combine with other organic molecules to form glycoproteins or lipoproteins.

Slide 33 Copyright © Elsevier Inc. All Rights Reserved. Protein

Slide 34 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) Nucleic acids Made up of nucleotide units sugar (ribose or deoxyribose) phosphate nitrogen base (adenine, thymine or uracil, guanine, cytosine) By directing the formation of structural and functional proteins, nucleic acids ultimately direct overall body structure and function

Slide 35 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) DNA (deoxyribonucleic acid) used as the cells master code for assembling proteins composed of deoxyribose (the sugar), phosphate, and four bases: cytosine, guanine, adenine, and thymine forms a double helix

Slide 36 Copyright © Elsevier Inc. All Rights Reserved. Organic Chemistry (contd.) RNA (ribonucleic acid) Used as a temporary working copy of a gene (portion of the DNA code) Composed of ribose (the sugar), phosphate, and four bases: adenine, uracil, cytosine, and guanine