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Essential Chemistry for Biology

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Presentation on theme: "Essential Chemistry for Biology"— Presentation transcript:

1 Essential Chemistry for Biology
Chapter 2 Essential Chemistry for Biology

2 Chapter 2 Two Lectures MasteringBiology Wednesday – Basic Chemistry
Friday – Biology of Water MasteringBiology Sunday night – First MasteringBiology Assignment Due

3 Outline for Essential Chemistry
Elements of Life Four most abundant elements in organisms Importance of trace elements Structure of Atoms Subatomic Particles Atoms of Life Isotopes and ions Chemical Bonds Covalent Bonds Hydrogen bonds Ionic bonds Hydrophobic interactions Chemical Reactions Water Four Properties pH and Buffers

4 Structural Hierarchy

5 Elements and Molecules
Atoms - building blocks of molecules Elements – types of atoms 92 natural elements Molecule – composed of two or more atoms. Compounds – molecules composed of more than one element. Emergent properties Sodium Chloride Sodium Chloride +

6 Molecular Formulas Water H20 Glucose C6H12O6

7 25 Elements Essential for Life
Oxygen (O): 65.0% 96% of living matter made of 4 elements. Oxygen O Carbon C Hydrogen H Nitrogen N Most of remaining 4% just 7 elements Remaining >0.1% are “Trace Elements” Calcium (Ca): 1.5% Phosphorus (P): 1.0% Potassium (K): 0.4% Sulfur (S): 0.3% Carbon (C): 18.5% Sodium (Na): 0.2% Chlorine (Cl): 0.2% Magnesium (Mg): 0.1% Trace elements: less than 0.01% Hydrogen (H): 9.5% Boron (B) Manganese (Mn) Chromium (Cr) Molybdenum (Mo) Cobalt (Co) Selenium (Se) Copper (Cu) Silicon (Si) (N): 3.3% Nitrogen Fluorine (F) Tin (Sn) Iodine (I) Vanadium (V) Iron (Fe) Zinc (Zn)

8 Essential Trace Elements

9 Atomic Structure Characteristics of Particles 2 Protons Nucleus 2
Location Atomic Number Atomic Mass Atomic Charge Atomic Volume (Size) 2 Protons Nucleus 2 Neutrons 2 Electrons Nucleus 2e– Figure 2.4 Two simplified models of a helium atom Electron cloud 9

10 Structure of Typical Atoms
Rule 1 Neutral atoms have equal number of protons and electrons Rule 2 Typically, atoms have equal number of protons and neutrons Structure of typical Nitrogen Atom

11 Exceptions to rules Exception to rule 1
Ions – unequal protons and electrons (electric charge) Exception to rule 2 Variable Isotopes – variable number of neutrons Nitrogen atom 7 proton and 7 electron Neutral Charge Nitrogen ion 7 proton and 6 electron Positive Charge 6 n 6 p 6 n 8 p C-12 6 proton and 6 neutron Common non radioactive isotope C-14 6 proton and 8 neutron Rare radioactive isotope

12 Properties of Common Atoms
Element Abv Atomic # Mass # Valence # Hydrogen H 1 Carbon C 6 12 4 Nitrogen N 7 14 3 Oxygen O 8 16 2

13 Four Chemical Bonds Strong Chemical Bonds Weak Chemical Bonds
Covalent Bonds Weak Chemical Bonds Ionic Bonds Hydrogen Bonds Other Interactions Hydrophobic Interactions

14 Ionic Bonds Attraction between positive ions and negative ions

15 Covalent Bonds

16 Properties of Covalent Bonds
Sharing of pair of electrons Strongest of chemical bonds Valence number Single, Double, and Triple bonds Important for Shape of Molecules Nonpolar/polar forms Ele-ment Valence # H 1 C 4 N 3 O 2

17 Non-Polar and Polar Covalent Bonds
Oxygen and Nitrogen have high electronegativity Hydrogen has low electronegativity

18 Hydrogen Bonds Attraction between a hydrogen with a partial positive charge and an electronegative atom (linked to less electronegative atom.) Requires polar bonds. Weak Interaction

19 Hydrophobic vs Hydrophobic Molecules
Measure of hydrophobicity = # of non-polar minus # of polar

20 Hydrophobic Interactions

21 Chemical Reactions (Rearranging Chemical Bonds)
2H O H2O

22 Water and Life Four special Properties Cohesion/Adhesion
Temperature Moderation Significance of Floating Ice Solvent Properties Other issues pH

23 Cohesion Surface Tension

24 Temperature Moderation
High Specific Heat Evaporative cooling

25 Floating Ice

26 Water’s Solvent Properties
Sodium ion in solution Chloride ion in solution Cl– Na Na Cl– Salt crystal

27 Disassociation of Water
H2O H OH- 55 M M M pH = -log [H+] Conc [H+] pH 10-2 M 2 10-3 M 3 10-4 M 4 10-5 M 5 10-6 M 6 10-7 M 7 10-8 M 8 10-9 M 9

28 Buffers Carbonic Acid (buffer in our blood) H2CO3 H+ + HCO3-
In response to rise in pH H2CO H HCO3- a drop in pH

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