The Chemistry of Life

Things you should be able to do… Describe how the unique properties of water support life on Earth. Explain how carbon is uniquely suited to form biological macromolecules. Describe how biological macromolecules form from monomers. Compare the structure and function of carbohydrates, lipids, proteins and nucleic acids in organisms. Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction. Explain how factors such as pH, temperature and concentration levels can affect enzyme function.

Vocabulary acid base buffer monomer polymer carbohydrate monosaccharide lipid nucleic acid nucleotide protein amino acid chemical reaction reactant product activation energy catalyst enzyme substrate atom nucleus electron element isotope compound ionic bond ion covalent bond molecule Van der Waals forces Hydrogen bond Cohesion Adhesion Mixture Solution Solute Solvent Suspension pH scale

The atom Basic Chemistry basic unit of matter Composed of protons, neutrons and electrons Electrons are involved in the interactions between atoms

Compound Basic Chemistry a substance formed by the chemical combination of two or more atoms in definite proportions Chemical formulas tell us the types of atoms and the proportion of atoms in a compound EX: H2O, C3H8, C6H12O6

Chemical bonds Basic Chemistry Hold atoms in a compound together Different types of chemical bonds include Ionic bonds = weaker bonds result from a transfer of electrons from one atom to another Covalent bonds = very strong bonds that result when two or more atoms share electrons Van der Waals forces = forces of attraction between molecules

Chemical Reactions Basic Chemistry Result when bonds between atoms are broken and rearranged to form new substances

Organic vs Inorganic compounds Basic Chemistry Organic vs Inorganic compounds Organic compounds = composed of carbon AND hydrogen EX: proteins, lipids, carbohydrates, DNA, RNA Inorganic compounds = not composed of BOTH carbon and hydrogen Ex: H2O, CO2

Molecular Structure Structure of Water H2O = 2 atoms of hydrogen and 1 atom of oxygen Covalent bonds between atoms = electrons are shared

Water is Polar Structure of Water Uneven sharing of electrons between oxygen and hydrogens Oxygen becomes slightly negative Hydrogens become slightly positive

Click here for animation Structure of Water Hydrogen bonds Van der Waal forces Form between water molecules Negative oxygen of one water molecule and the positive hydrogen of another water molecule Explain ALL other properties of water Cohesion, adhesion, high heat capacity, density Click here for animation

DRAW THIS IN YOUR NOTES TO SHOW HYDROGEN BONDING BETWEEN MOLECULES The opposite partial charges of the hydrogen and oxygen atoms attract each other, and so these regions will likely be found together between water molecules DRAW THIS IN YOUR NOTES TO SHOW HYDROGEN BONDING BETWEEN MOLECULES

EXPLAIN WHY TWO WATER MOLECULES WOULD NOT ALIGN AS SHOWN IN THIS DIAGRAM The partial positives of the hydrogen atoms repel each other, making it unlikely that water molecules will be arranged in this way.

1. Cohesion Properties of Water tendency of water to stick to itself causes surface tension More force is required to break the surface of a liquid

2. Adhesion Properties of Water tendency of water to stick to other substances

3. Water and Heat Energy Properties of Water Water has a high capacity to absorb and retain heat (specific heat) Water requires more heat energy to change temperature Even if the air temperature changes drastically, water will resist the change Water in the body helps maintain body temperature Water on earth helps regulate temperature

4. Density Properties of Water Density = mass per unit volume Water has a greater density as a liquid than a solid Frozen water floats on the surface of ponds and other bodies of water leaving denser liquid water beneath

When leafy green vegetables are frozen and then thawed, their texture changes. Can you explain why freezing causes this change? Plant cells contain a high percentage of water, particularly in the central vacuole. When frozen, the density of water decreases and the ice takes up a larger volume insides the cell. This causes the cell wall to burst and results in leafy vegetables losing their crunch.

5. Water is the Universal Solvent Properties of Water 5. Water is the Universal Solvent Solvent = substance which dissolves other substances “Like dissolves like” Water dissolves ionic substances and polar molecules Salt is polar and therefore dissolves in water Lipids are nonpolar and therefore don’t dissolve in water

Background Acids, Bases and pH Water sometimes splits apart to form ions Water is neutral because [OH-] = [H+]

pH scale Acids, Bases and pH Ranges from 0 to 14 Measure of the concentration of hydrogen ions Concentration of H+ ions determines whether solutions are acidic or basic Pure water has a pH of 7 = NEUTRAL Optimal pH of blood = 7.3 Each step on the pH scale represents a factor of 10

Defined Acids, Bases and pH Acids Bases form H+ in solution have high H+ concentration have pH less than 7 Bases Form OH- in solution have low H+ concentration have pH greater than 7

Buffers Acids, Bases and pH Control pH in most living things Prevent sharp changes in pH Important in maintaining homeostasis Changes in pH can unfold enzymes, making them useless in carrying out chemical reactions

Quick Lab Determining pH of household items Predict whether the household samples provided are acidic or basic Test pH of each item with different indicator papers Construct a pH scale (1-14) and write each item you tested in the appropriate place on the pH scale

Organic compounds Chemistry of Carbon Organic compounds contain carbon atoms bonded to hydrogen atoms All life on earth is carbon-based Covalent bonds between atoms = electrons shared can be single, double or triple

Unique Properties of Carbon Chemistry of Carbon Unique Properties of Carbon Carbon can form 4 bonds Carbon can bond with other elements (H, O, N, P,) Carbon can bond with itself Can form chains unlimited in length Carbon chains can be branched or form rings

C C C Unique Properties of Carbon Chemistry of Carbon How many hydrogen atoms are needed to make up one molecule of the compound C C C

C C C Unique Properties of Carbon Chemistry of Carbon How many hydrogen atoms are needed to make up one molecule of the compound C C C

Unique Properties of Carbon Chemistry of Carbon Unique Properties of Carbon

C C C Unique Properties of Carbon Chemistry of Carbon How many hydrogen atoms are needed to make up one molecule of the compound C C C

Carbon-based molecules Chemistry of Carbon Carbon-based molecules (macromolecules, biomolecules, organic molecules) Macromolecules = large, complex molecules such as lipids, carbohydrates, proteins and nucleic acids Monomer = single unit Polymer = many “units” linked together through polymerization

1. Carbohydrates (sugars and starches) Chemistry of Carbon 1. Carbohydrates (sugars and starches) Structure: Contain carbon, hydrogen and oxygen Hydrogen : oxygen ratio is 2:1 Function: Quick energy Structural support (cell walls and cell membranes) Other info: Monomer = monosaccharide (simple sugar) Examples: glucose, fructose Polymer = polysaccharide Examples: glycogen, starch, cellulose

What does each brown shape represent? Is each brown shape a monomer or polymer?

2. Lipids (fats, oils, waxes) Chemistry of Carbon 2. Lipids (fats, oils, waxes) Structure: Contain carbon, hydrogen and oxygen (NO 2:1 hydrogen : oxygen ratio) Contain long hydrocarbon chains Function: Long-term energy (storage) Structural support (cell membranes) Waterproof coverings (bird feathers) Hormones (chemical messengers Other info: Hydrophobic (not soluble in water) Not a true monomer: made up of glycerol and fatty acids Saturated vs unsaturated lipids

2. Lipids (fats, oils, waxes) continued Chemistry of Carbon 2. Lipids (fats, oils, waxes) continued Other info: Saturated fatty acids have all single bonds between carbons in chain unsaturated fatty acids may have one or more double bonds between carbons in chain

2. Lipids (fats, oils, waxes) continued Chemistry of Carbon 2. Lipids (fats, oils, waxes) continued Which of the four fatty acids is saturated? Which of the fatty acids are unsaturated? How does melting point change as the # of carbon-carbon double bonds increases? Which fatty acid is solid at room temperature? Which is liquid at room temperature?

Saturated or Unsaturated?

Carb or Lipid?

Carb or Lipid? Venn Diagram Crash Course

3. Nucleic Acids Chemistry of Carbon Structure: Function: Other info: contain C, H, O, N AND P Function: store and transmit hereditary material Other info: monomer = nucleotide Polymer = DNA and RNA

4. Proteins Chemistry of Carbon ENERGY Structure: Function: Contain C, H, O and N Function: Control chemical reaction rate Regulate cell processes (transport) Help fight disease Transport substances around the body Other info: Monomer = amino acid Polymer = polypeptide chain Shape is crucial for a proteins function Amino acid sequence determines shape of protein

WHO AM I? I store hereditary material. I am made up of monosaccharides. I give cells QUICK energy. I contain the elements C, H, O and N. My monomer is the nucleotide. My monomer is the amino acid. I am used for long-term energy storage. I am a hydrocarbon chain. I am a hydrocarbon chain with NO double bonds.

Carb, lipid, protein or NA?

Carb, lipid, protein or NA?

Carb, lipid, protein or NA?

Carb, lipid, protein or NA?

Monomer or polymer? Glucose monosaccharide Starch Nucleotide cellulose Protein Amino acid Glycogen polysaccharide Carbon compounds flipchart Keystone MC carbon compounds

Chemical Reactions Chemical Reactions Chemical bonds between atoms are broken and rearranged to form new substances Reactants = what you start with Products = what you end with

Chemical Reactions Chemical Reactions Dehydration synthesis = joins monomers together to form polymers Water is a product of the reaction

Chemical Reactions Chemical Reactions Hydrolysis= breaks a polymer down into monomers Water is a reactant of the reaction Reverse of dehydration synthesis

Quick Check Chemical Reactions Which of these is not produced during dehydration synthesis? Water Glucose Phospholipid starch

Energy and Chemical Reactions Activation energy = energy needed to get a reaction started Chemical reactions that release energy are exothermic Chemical reactions that absorb energy are endothermic

Exothermic Reactions release energy Chemical Reactions Exothermic Reactions release energy

Endothermic Reactions absorb energy Chemical Reactions Endothermic Reactions absorb energy

ENDOTHERMIC or EXOTHERMIC? Pre-Class ENDOTHERMIC or EXOTHERMIC?

The role of catalysts Chemical Reactions A catalyst in general speeds up a chemical reaction Lighter fluid is a catalyst Enzymes are biological catalysts – they speed up chemical reactions by lowering the activation energy Enzymes are proteins Enzymes are not used up during a reaction

Enzyme Specificity Chemical Reactions Enzymes are specific One enzyme generally catalyzes one reaction Reactants of the reaction are called the substrates Enzyme binds to substrate at an “active site” Shape of the active site “fits” the shape of the substrates Binding of the substrate with the active site causes the substrate to be converted to products

Enzymes and Optimal Conditions Chemical Reactions Enzymes and Optimal Conditions Temperature Optimum temp = the temp at which the enzyme works “the best” High temperatures “denature” or unfold an enzyme, making it useless Low temperatures slow pH activity

Enzymes and Optimal Conditions Chemical Reactions Enzymes and Optimal Conditions pH Optimum pH = the pH at which the enzyme works “the best” Different enzymes have different optimums Enzymes in the stomach work best at a pH of 2 but enzymes in the small intestine work best at a pH of 8

Factors which may affect enzyme activity Chemical Reactions Factors which may affect enzyme activity Substrate concentration Remember, substrate = reactant of reaction Initially, increasing substrate concentration will increase enzyme activity but eventually the reaction rate will level off

Factors which may affect enzyme activity Chemical Reactions Factors which may affect enzyme activity Enzyme concentration Increasing enzyme concentration will increase the rate of the reaction

How does the picture of the lock and key relate to enzymes?

Why is a cycle diagram a good way to show how enzymes work?

How does pH affect enzyme activity?

How does temperature affect enzyme activity?

How does substrate concentration affect enzyme activity?

How does enzyme concentration affect enzyme activity?