1. Chapter 2 Lecture Outline The Nature of Life Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Outline  Attributes of Living Organisms  Chemical and Physical Bases of Life The Elements: Units of Matter Molecules Valence, Bonds and Ions Acids, Bases and Salts Energy Chemical Components of Cells Monomers and Polymers – Carbohydrates – Lipids – Proteins – Nucleic Acids

3. Attributes of Living Organisms  Composition and Structure Cells: All Complex Cells Have – Cytoplasm – Cell Membrane – Nucleus Plant Cells also Have: – Cell Walls Drawing of plant cell

4. Attributes of Living Organisms …  Growth  Reproduction

5. Attributes of Living Organisms …  Response to:

6. Attributes of Living Organisms …  Metabolism All chemical reactions – Photosynthesis – Digestion – Respiration – release of energy from food – Assimilation - Conversion of raw materials into cell substances

7. Attributes of Living Organisms …  Complexity of Organization Elements/atoms  Molecules  Cells  Tissues  Organs  Organ Systems  Organism Microscopic View of the Cells within a Leaf

8. Attributes of Living Organisms …  Environmental Adaptation– Natural Selection Many generations Some Organisms have genetic characteristics  survive and reproduce – Their offspring have the same genetic characteristics Other Organisms without these characteristics won’t do so well! The Population will have more and more individuals with the survival characteristics

9. Attributes of Living Organisms …  Movement - Organismal level - Cell level – Cytoplasmic streaming occurs within cell:

10. Chemical and Physical Bases of Life THE ELEMENTS: UNITS OF MATTER  Energy  Matter Mass Composed of elements – Examples: – composed of ATOMS Model of an oxygen atom

11.  Elements & Atoms Atoms o Nucleus Protons Neutrons o Electron Orbitals Electrons: Atomic Number = identifies elements Atomic Mass = Model of an oxygen atom

12.  Isotope = ____________________________ Radioactive isotopes are: Oxygen isotopes

13.  IONS = Sodium Atom Sodium Ion Chlorine Atom Chloride Ion

14. Chemical and Physical Bases of Life MOLECULES  Molecule - Two or more atoms bound together Smallest independently existing particle :  Compound - Two or more different elements bond together Water molecule

15. PRACTICE QUESTIONS  Two or more elements bonded together in a particular ratio is called a(an) _____________  An atom that has lost or gained electrons is called a(an) _____________  If temperature is increased, the motion of a molecule ________________  The smallest, stable subdivision of an element is a(an) _________________

16. Chemical and Physical Bases of Life VALENCE, BONDS, AND IONS  Bonds = 1 bond = ____ electrons 4 Types of Bonds – Based on what happens to the electrons of the bond Covalent Polar Covalent Nonpolar Ionic Hydrogen bonds between molecules

17.  Covalent Bonds Form when: Electrons travel ___________________ Nonpolar – Polar - H H O Water O O Oxyen

18. Water has Polar Covalent Bonds – Water’s Shape: – Polar molecule: Slightly positive hydrogen atoms are attracted to: Cohesion - Attraction of: – Capillary movement in plants Adhesion - Attraction of: IMPORTANCE OF WATER 1) Solvent 2) Water Movement in Plants Cohesion of water molecules

19.  Ionic Bonds Ionic bonds form when:

20.  Hydrogen Bonds Bond between two _____ Usualy involve what elements: Are Polar molecules Are Weak Bonds Cohesion of water molecules

21. PRACTICE QUESTIONS  A chemical bonds is formed by two __________  When a molecule is Polar: a) The electrons in the bonds are equally shared b) Radioactive Isotopes give up neutrons to form the bond c) The molecule has an end that is partially positive charged and another end that is partially negative charged d) Its motions stops in very low temperatures

22.  CHEMICAL REACTIONS Reactants and Products Collisions of Reactants cause: ______ Catalyst: ___________________________ – Enzyme: _______________________________ Sucrase Sucrose ------  Glucose + Fructose – If an organism has no chemical reactions in its body it is ____________

23.  Chemical Reactions … Sodium metal + Chlorine gas  Salt Reactants  Products Water molecule

24. PRACTICE QUESTIONS  Cohesion is the attraction of _________ molecules.  Chemical Reactions involve which of the following: 1. random collisions of the reactants 2. the removal of protons from one or more chemicals 3. keeping all the same bonds in the reactants 4. Catalyst is required a) “1” onlyc) “1” and “3” b) “4” onlyd) “1” and “4” e) “1,” “2,” and “4”

25. Chemical and Physical Bases of Life ACIDS AND BASES  Acids:  Bases: pH scale = Range = 7 = Neutral 1-7 = Acidic 7-14 =Alkaline IMPORTANCE: Soils

26. Movement of Chemicals  DIFFUSIONOSMOSIS  ACTIVE TRANSPORT Energy Protein Carrier Molecule Low  High

27. Chemical and Physical Bases of Life CHEMICAL COMPONENTS OF CELLS  About 96% of a cell is:  Categorizing Chemicals INORGANIC – Examples: ORGANIC – BIOCHEMICALS

28. Chemical and Physical Bases of Life BIOCHEMICALS …  Polymers - Monomers

29. PRACTICE QUESTIONS  The movement of a substance from a higher concentration to a lower concentrations is called ___________.  Name the 4 elements which make up the majority of a living organisms: ___ ___ ___ ___  Organic Chemicals always have a framework made of ___________.  A small subunit that is used to make a polymer is called a(an) ____________.

30. Carbohydrates Elements: Ratio of Elements: General Function: TYPES Monosaccharides - Simple sugars Structure Examples:  Carbohydrates most abundant

31. Disaccharides: Examples Polysaccharides: Structure: Examples – Starch = coils of glucose molecules o Function: – Cellulose = unbranched chain of glucose molecules o Function

32. Lipids  Lipids: General Function: Contain Elements: Element Ratios: Fats and oils are produced from one molecule of glycerol and three fatty acid molecules. Most fatty acids consist of:

33. – Saturated - – Unsaturated - Structure of a fat molecule

34.  Waxes - long-chain fatty acids bonded to a long chain alcohol Location & Function in Plants:  Phospholipids - Constructed like fats, but one of the fatty acids is replaced by a phosphate group Function:

35. PRACTICE QUESTIONS  What Biochemical does not mix with water? _____________  What Biochemical has a ratio of 1 C: 1 O: 2 H ? _____________  A Phospholipid differs from a Fat molecule in that is has a Phosphate and ____ Fatty acids.  Starch in plants functions in what: a) storage form of energy b) as an enzyme c) as an insulation in leaves

36. Proteins, Polypeptides, and Amino Acids  Proteins: - General Functions: - Contain Elements: Polypeptides: simplest form; are composed of: Structure of amino acid, glycine – Each amino acid is composed of: Repeats of CCN o Amino group (-NH 2 ) o Carboxyl group (-COOH) o R group -

37. Proteins, Polypeptides, and Amino Acids  Polypeptide Structure Primary Structure Secondary Structure – Formation of an alpha helix or of pleated sheets due to:

38. Proteins, Polypeptides, and Amino Acids  Polypeptide Structure Tertiary Structure Quaternary Structure

39. Protein Types According to Functions  Structural  Storage  Movement  Transport and Carrier  Enzymes

40. Enzymes  Enzymes Breaking bonds: Increase reaction rates Lower the energy needed for a chemical reactions to occur– Energy of activation Active Site:

41. Enzymes Mode of action of an enzyme  Enzymes temporarily bond with substrate. Substrate fits into active site of enzyme. Reaction occurs rapidly and products are released. Enzyme remains unchanged and capable of catalyzing another reaction.

42. PRACTICE QUESTIONS  The subunit of Proteins is _________________.  The tertiary structure of a protein is the: a) Linear sequenceb) 3-dimensional shapes b) 3-dimensional shapesc) helixes and/or sheets e) two or more polypeptides  T or F: Enzymes become part of the product of a reaction.  T or F: Carrier proteins help move substances from a lower to a higher concentration inside or outside of a cell.

43. Nucleic Acids  Nucleic acids 4 Major elements contained: There are two types: – Deoxyribonucleic Acid (DNA) – Ribonucleic Acid (RNA)  DNA consists of a double helix of repeating subunits of 4 kinds of nucleotides. Nucleotides are composed of a nitrogenous base, a five-carbon sugar and a phosphate. Nucleotide structure

44.  CODE:  DNA RNA  Functions: * Functions:

45.  Gene: Sequence of DNA that: That protein then causes a particular characteristic

46. PRACTICE QUESTIONS  Name the 3 parts of a Nucleotide: __ __ __  The basic shape of DNA is what? _________  T-F: DNA is important because it codes for all the proteins in an organisms and thereby control all the traits of the organism.  T-F: RNA functions by helping DNA translate its code into proteins

47. Outline  Attributes of Living Organisms  Chemical and Physical Bases of Life The Elements: Units of Matter Molecules Valence, Bonds and Ions Acids, Bases and Salts Energy Chemical Components of Cells Monomers and Polymers – Carbohydrates – Lipids – Proteins – Nucleic Acids

48. Copyright © McGraw-Hill Companies Permission Required for Reproduction or Display