The Chemical Context of Life

2-2 Properties of Water The Chemical Context of Life • KEY CONCEPTS: • Matter consists of chemical elements in pure form and in combinations called compounds. • An elements properties depend on the structure of its atoms • The formation and function of molecules depend on chemical bonding between atoms • Chemical reactions make and break chemical bonds.

2-2 Properties of Water Atoms are the ________________: basic unit of MATTER PROTONS (+) ______________ ______________ are found ______________ ______________ ___________________ in ____________________ NEUTRONS in NUCLEUS ELECTRONS (-) orbit outside nucleus energy levels

2-2 Properties of Water Atoms differ in numbers of _______, ________,& _______ PROTONS NEUTRONS ELECTRONS

2-2 Properties of Water electric charge + Na Atoms that have gained or lost electrons have an_____________ andare called__________ They are writtenwith a + or –next to theirsymbol IONS - Cl

2-2 Properties of Water Atoms/ions important for living things Used to make bigger molecules Ions = electrically charged atoms Carbon - C • ____________ • ____________ • ____________ • ____________ • ____________ • ____________ • ____________ • ____________ • ____________ • ____________ • ____________ Sodium – Na+ Oxygen - O Chloride – Cl- Hydrogen - H Potassium – K+ Nitrogen - N Calcium – Ca++ Sulfur - S Hydrogen – H+ Phosphorus - P

2-2 Properties of Water Hydrogen Ions (H+) The number of H+ ions determines how _______ a solution will be. acidic More H+ = more acidic

2-2 Properties of Water ATOMS CAN JOIN TOGETHER TO MAKE____________ MOLECULES Ex: Joining 2 HYDROGENatoms with 1 OXYGEN atom makes one ______ molecule. WATER what kind A Chemical Formula tells _________ of and __________ atoms are in a molecule EX: ________ how many H2O

2-2 Properties of Water VERY, VERY LARGE MOLECULES = ____________________ MACROMOLECULES EXAMPLE: Insulin = C254 H377 N65 O76 S6

2-2 Properties of Water MOLECULES CAN BE SHOWN IN DIFFERENT WAYS H2O

2-2 Properties of Water Polar Molecules Because of the location of electrons in molecules, some molecules have an uneven pattern of electric charge More ___ on one side; More ___ on the other EX: water + -

2-2 Properties of Water EX: PHOSPHOLIPIDS The same molecule can have bothPOLAR and NON-POLARparts Polar head NON-polartails

2-2 Properties of Water WHAT HOLDS MOLECULES TOGETHER? Molecules are held together by the ________ between ______________ regions of nearby molecules = _____________________ attraction oppositely charged van der Waals forces

2-2 Properties of Water HYDROGEN BONDS Bonds that form between the_________ charged Hydrogen atom in one molecule and a __________ charged atom in a nearby molecule are called _____________________ positively negatively HYDROGEN BONDS EX: water molecules are held together by Hydrogen bonds Hydrogen bond animation

2-2 Properties of Water _________ is the most important atom found in living things CARBON four It can join to _______ other atoms at same time It can form ______ or _____ so it can make lots of different kinds of molecules. chains rings

2-2 Properties of Water __________ moleculesare found __________ and _____________ atoms ORGANIC in living things contain CARBON

2-2 Properties of Water “Like dissolves like” HYDROPHILIC ____________________ means “water loving” _________ groups/molecules try to _________ and touch water or ______________ molecules POLAR be near other polar Water makes a great solvent in living things because so many molecules found in living things are polar or have a charge.

2-2 Properties of Water “Like dissolves like” HYDROPHOBIC _________________ means “water fearing” ___________ groups/molecules try to _________ other __________ molecules and __________ ________ molecules NON-polar NON-polar be near away from polar Oil based paints dissolve in solvents such as turpentine . . . not water.

2-2 Properties of Water “Like dissolves like” Soap works because it has a _____________ that dissolves grease and a __________ that dissolves in water to wash away oily dirt. NON-polar end Polar end

2-2 Properties of Water A chemical equation tells what happens in a chemical reaction when molecules interact. NaOH + HCl → NaCl + H20 _______________ _______________ Molecules that react Molecules that are produced → REACTANTS PRODUCTS

2-2 Properties of Water REMEMBER:ALL the chemical reactions that happen in cells = _____________ METABOLISM join Chemical reactions can _____ molecules together. Chemical reactions can ______ molecules apart. break

2-2 Properties of Water One way to join molecules to make a bigger molecule is by removing a _______ molecule to make a bond. = ____________________ reaction WATER dehydration synthesis See an animation http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html

2-2 Properties of Water DEHYDRATION SYNTHESIS“dehydration” “synthesis” =_____________ _____________ water loss put parts together http://io.uwinnipeg.ca/~simmons/macromol/sld003.htm

2-2 Properties of Water POLYMERIZATION is a kind of synthesis reaction in whichmany small subunits thatare similar join to make a bigger molecule These small units arecalled ______________ The big molecule theymake is called a _____________ MONOMERS POLYMER

2-2 Properties of Water EXAMPLE: _________ subunits (A,T,G,C) join together to make a _____ molecule Nucleotide DNA

2-2 Properties of Water Chemical reactions can also break molecules apart. ______________ = kind of chemical reaction in which a molecule is broken apart by addinga________ molecule. “_____” = water “_____” = break apart HYDROLYSIS WATER hydro lysis See an animation http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html

2-2 Properties of Water opposite HYDROLYSIS is the _________ of DEHYDRATION SYNTHESIS. Adding a water molecule breaks the bond.

2-2 Properties of Water ATP is the energy molecule used by all cells. Breaking a bond using hydrolysis is the way ENERGY is released. More on this is Chapters 7, 8,& 9

2-2 Properties of Water Living things use BOTH of these kinds of _______ (and MORE) to get the materials they need. reactions

2-2 Properties of Water WATER is important for all living things Average person ~~ 60-70% water Babies ~~ 78% Human brain ~~90%

2-2 Properties of Water WHY Water is important to cells: POLAR DISSOLVE 1. It is __________ molecule so it can ____________ lots of different substances. 2. It can _________ lots of ______ WITHOUT changing temperature very much. (That helps with HOMEOSTASIS) 3. ____________BONDS form between water molecules so they stick together. 4.Water is an important ___________________ in many CHEMICAL REACTIONS. absorb HEAT HYDROGEN REACTANT/PRODUCT

The Chemical Context of Life