Chapter 2 Chemistry of Life

A water molecule is polar b/c there is an uneven distribution of electrons between oxygen and hydrogen atoms POLARITY: Oxygen end - slightly negative Hydrogen end - slightly positive

The Amazing Properties of Water Polar Molecule One region more negative and other more positive Water molecule is bent  oxygen is at one end and hydrogen is at other + + -

Hydrogen Bonds Water molecules attract each other b/c of their charges This bond is called a hydrogen bond. Not very strong, but responsible for unique properties of water. One water molecule can have up to 4 hydrogen bonds at the same time

Cohesion An attraction between molecules of the same substance Water is very cohesive because it sticks to itself Why? – The pull of hydrogen bonds causes the water molecules to be drawn inward.

Adhesion The attraction between molecules of different substances. Water is very adhesive because it sticks to other substances Example:Meniscus in a graduated cylinder. The adhesion between water molecules glass molecules.

Solutions Components are evenly mixed throughout the solution. The solution looks uniform throughout. Example: table salt and water 2 parts: solute and solvent

Cl - Water Cl - Na + Water Na + Figure 2-9 NaCI Solution

Cl - Water Cl - Na + Water Na +

Solute vs. Solvent Solute is dissolved by the solvent. Solute-substance that is dissolved Solvent-substance that does the actual dissolving What is the universal solvent???

Suspensions Materials do not dissolve but they are so small they do not settle; they remain suspended. Mixtures of water and non-dissolved material Example: cloudy river water

What is Blood? Solution and a suspension Solution - dissolved sugars, sodium, potassium, Oxygen, Carbon Dioxide Suspension - white blood cells, red blood cells

Acids, Bases, and pH

Acids Any compound that produces H+ (hydrogen ions) in solution pH < 7 (less than 7) Also called acidic Bases Any compound that produces OH- (hydroxide ions) in solution pH > 7 (greater than 7) Also called alkaline

pH Scale Measures the H+ concentration 0 – 14 7 is a neutral solution = pure water

Oven cleaner Bleach Ammonia solution Soap Sea water Human blood Pure water Milk Normal rainfall Acid rain Tomato juice Lemon juice Stomach acid Neutral Increasingly Basic Increasingly Acidic pH Scale

Buffers pH in most human cells must be between 6.5 and 7.5 If higher or lower  affects chemical reactions in human cells Therefore, controlling pH is very important for maintaining internal balance (homeostasis). This is done through buffers. Buffers: Weak acids and bases that react with strong acids and bases to prevent sharp changes in pH. Example: Tums (stomach antacid)

2-3 Organic (Carbon) Compounds

Organic Chemistry Study of compounds with bonds between carbon atoms Carbon – 4 outer electrons  can form 4 strong covalent bonds (sharing electrons)

Macromolecules/Polymers Giant molecules Formed by bonding smaller molecules Monomers- smaller units Join to form Polymers  process called polymerization

Organic Compounds 1. Carbohydrates = sugars 2. Lipids 3. Nucleic Acids 4. Proteins

Carbohydrates C, H, O Ratio of 1:2:1 – C 6 H 12 O 6 Main source energy Structural purposes 3 groups…

Monosaccharides – simple sugars Used for quick energy Monomers Examples: Glucose – blood sugar Fructose – fruit sugar Galactose – milk sugar

Disaccharides – 2 sugars Quick energy Examples: Sucrose – sugar cane Lactose – milk sugar Maltose – important for fermentation

Polysaccharides – many sugars (complex) Long chains of simple sugars Polymers Stored energy – released slowly

Examples: Starch – stored in plants ex. Grains, pastas Glycogen – stored in animal muscle Cellulose – used for structural purposes (cell walls)

Starch Glucose Figure 2-13 A Starch

Lipids - Fats Consist mainly of C and H fat, oil, wax **Saturated  heart disease Uses Structural Purposes – cell membranes/water proof coverings Energy Storage Chemical Messengers – component of steroids

Nucleic Acids – DNA/RNA Consist of H, C, O, N and P Store and transmit genetic (hereditary) information Made of nucleotides (monomers)

Proteins Made of amino acids (monomers) Consist of C, H, N, and O Used for: Control and regulate chemical reactions (enzymes) Structural purposes (muscle and bone) Transportation in and out of cells Fighting Disease

General structureAlanineSerine Figure 2-16 Amino Acids Amino groupCarboxyl group

Amino acids Figure 2-17 A Protein Proteins can have up to 4 levels of organization 1.Sequence of amino acids in chain 2.Amino acids within chain twist/fold 3.Chain itself is folded 4.If more than one chain, each chain has specific arrangement organise-to-form-functional-protein

2-4 Chemical Reactions and Enzymes

Chemical Reactions Process that changes one set of chemicals into another set of chemicals (slow=rust, fast=H gas ignited with O) Reactants- elements/compounds that enter into reaction (left side) Products- elements/compounds produced by reaction (right side)

CO 2 + H 2 O  H 2 CO 3 Which are the reactants??? Which are the products???

Energy in Chemical Reactions Exothermic- reaction that releases energy Usually spontaneous Energy released in form of heat/light/sound Reactants have more energy than products Ex. Thunder & Lightning Endothermic- reaction that absorbs energy Products have more energy than reactants Ex. Digesting food All of this energy is required for life processes

Activation Energy- amount of energy needed to start reaction

Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants Figure 2-19 Chemical Reactions

Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants Figure 2-19 Chemical Reactions

Enzymes Proteins that act as biological catalysts Catalyst- substance that speeds up rate of chemical reaction by lowering activation energy Cells use enzymes to speed up reactions that take place inside cells

Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Reaction pathway with enzyme Reactants Products Effect of Enzymes

Reactants are called SUBSTRATES if enzymes are involved in the chemical reaction Enzymes provide a site where SUBSTRATES (reactants) can be brought together  activation site This site reduces amount of energy needed for reaction  lowers activation energy

Glucose Substrates ATP Substrates bind to enzyme Substrates are converted into products Enzyme-substrate complex Enzyme (hexokinase) ADP Products Glucose-6- phosphate Products are released Figure 2-21 Enzyme Action Active site

Glucose Substrates! ATP Substrates bind to enzyme Substrates are converted into products Enzyme-substrate complex Enzyme (hexokinase) ADP Products Glucose-6- phosphate Products are released Figure 2-21 Enzyme Action Active site

Glucose Substrates! ATP Substrates bind to enzyme Substrates are converted into products Enzyme-substrate complex Enzyme (hexokinase) ADP Products Glucose-6- phosphate Products are released Figure 2-21 Enzyme Action Active site

Glucose Substrates! ATP Substrates bind to enzyme Substrates are converted into products Enzyme-substrate complex Enzyme (hexokinase) ADP Products! Glucose-6- phosphate Products are released Figure 2-21 Enzyme Action Active site

Suffixes to note… - OSE = SUGAR - ASE = ENZYME Example: Lactase breaks down Lactose enzyme activity animation!