Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 2 The Chemical Context of Life

Fig. 2-2b What would be the results if the unprotected saplings’ inability to grow in the devils’ gardens was caused by a chemical released by the Duroia trees rather than by the ants? Dead leaf tissue (cm 2 ) after one day Inside, unprotected Inside, protected Outside, unprotected Outside, protected Cedrela saplings, inside and outside devil’s gardens RESULTS

Fig. 2-3c What are some properties of sodium? Chlorine? Are they present in sodium chloride? Sodium chloride Sodium Chlorine

Table 2-1 Highlight/underline the elements that causes goiters and decrease in growth in plants.

Fig. 2-4a Describe the effects of essential element deficiencies.

Fig. 2-7 Why is this imaging technique better than taking a piece of the tissue and staining it with dyes? Cancerous throat tissue

Fig. 2-8 What happens to energy when electrons move away from the nucleus? Towards nucleus? (a) A ball bouncing down a flight of stairs provides an analogy for energy levels of electrons Third shell (highest energy level) Second shell (higher energy level) Energy absorbed First shell (lowest energy level) Atomic nucleus (b) Energy lost

Fig. 2-9 What is the atomic number of magnesium? How many protons and electrons does it have? How many electron shells? How many valence electrons? Hydrogen 1 H Lithium 3 Li Beryllium 4 Be Boron 5 B Carbon 6 C Nitrogen 7 N Oxygen 8 O Fluorine 9 F Neon 10 Ne Helium 2 He Atomic number Element symbol Electron- distribution diagram Atomic mass 2 He 4.00 First shell Second shell Third shell Sodium 11 Na Magnesium 12 Mg Aluminum 13 Al Silicon 14 Si Phosphorus 15 P Sulfur 16 S Chlorine 17 Cl Argon 18 Ar

Electron-distribution diagram (a) (b) Separate electron orbitals Neon, with two filled shells (10 electrons) First shellSecond shell 1s orbital2s orbitalThree 2p orbitals (c) Superimposed electron orbitals 1s, 2s, and 2p orbitals x y z Fig What do the orbitals describe?

Fig. 2-12b Covalent or ionic bond? (b) Oxygen (O 2 ) Name and Molecular Formula Electron- distribution Diagram Lewis Dot Structure and Structural Formula Space- filling Model

Fig. 2-12c Polar covalent or nonpolar covalent? (c) Water (H 2 O) Name and Molecular Formula Electron- distribution Diagram Lewis Dot Structure and Structural Formula Space- filling Model

Fig. 2-12d Polar covalent or nonpolar covalent? (d) Methane (CH 4 ) Name and Molecular Formula Electron- distribution Diagram Lewis Dot Structure and Structural Formula Space- filling Model

Fig What results from the difference in electronegativity between hydrogen and oxygen?  – – ++ ++ H H O H2OH2O

Fig Covalent or ionic bond? NaCl Na Cl Na Sodium atom Chlorine atom Cl Na + Sodium ion (a cation) Cl – Chloride ion (an anion) Sodium chloride (NaCl)

Fig Another name for ionic compound? Na + Cl –

Fig Draw five water molecules using structural formulas and indicating partial charges, and show how they can make hydrogen bonds with each other.    ++ ++    ++ ++ ++ Water (H 2 O) Ammonia (NH 3 ) Hydrogen bond

Fig. 2-17b What determines the shape of a molecule? Space-filling Model Ball-and-stick Model Hybrid-orbital Model (with ball-and-stick model superimposed) Unbonded electron pair 104.5º Water (H 2 O) Methane (CH 4 ) Molecular-shape models (b)

Fig. 2-18a Are these two molecules identical? Explain your rationale. Natural endorphin Morphine Key Carbon Hydrogen Nitrogen Sulfur Oxygen Structures of endorphin and morphine (a)

Fig. 2-18b How does this relate to the structure=function concept? Natural endorphin Endorphin receptors Brain cell Binding to endorphin receptors Morphine (b)

Fig. 2-Label reactants and products. _____________ Reaction ________________ 2 H 2 O2O2 2 H 2 O

Fig Explain how this photo relates to the reactants and products in the equation for photosynthesis given in the textbook.