Big Ideas: Living Systems are made up of 5 types of molecule a. Water b. Carbohydrates c. Lipids d. Proteins e. Nucleic Acid Sugars/Starches All help to maintain HOMEOSTASIS Fats DNA & RNA
2. Organisms are made up of different arrangements of these molecules, giving all life a biochemical framework.
II. Inorganic vs. Organic Living systems can be categorized into inorganic and organic molecules. 1. INORGANIC: molecules containing 1 or no carbon atoms Ex: H2O, CO2, NaCl
2. ORGANIC: molecules containing 2 or more carbon atoms Ex: hydrocarbons (fuels like methane), Carbs, lipids, proteins, nucleic acids
III. Chemistry of Water Essentials: Most CELLS are surrounded by water and cells themselves are about 70-95% water The abundance of water is the major reason Earth is habitable and essential for all living things.
B. 6 Characteristics of WATER: Structure:
Water contains 2 HYDROGEN atoms and 1 OXYGEN atom
Attached by COVALENT bonds Chemical Formula = H2O Structural Formula= O H H
2. Polarity: What demo/activity demonstrated polarity?
Water has slightly POSITIVE and NEGATIVE ends
Ex: Electrons in water molecules spend more time near the oxygen side than the hydrogen side, creating partially charged ends.
Lewis Structure of Water: Lone pairs of electrons (-) Covalent bond…shared electron between H and O (+) (+)
3. Bond Type: What demo/activity demonstrated bonds in water molecules?
Water is bonded together by COVALENT BONDS: which is the sharing of valence electrons
Two types of covalent bonds: Nonpolar Covalent: Share electrons EQUALLY even distribution means no charge Ex: H2 Gas Cl2
b. Polar Covalent: Share electrons UNEQUALY causes a negative charge at one end and a positive charge at the other Ex. H2O HCl
So…Why does water “stick” to itself and to other objects? Zero Gravity Water Balloons
4. Creates Hydrogen Bonds: What demo/activity demonstrated hydrogen bonds?
Water can bond with other WATER molecules or other POLAR molecules
Form hydrogen bonds: which are WEAK ATTRACTIONS between molecules.
Hydrogen bonding is the cause of ADHESION COHESION CAPILLARY ACTION SURFACE TENSION
Rule: Usually form between H, F, O, N
**This property is what orders other molecules into a higher level of structural organization. Ex: Cell membrane, DNA, Proteins
Hydrogen bonding song
5. Relationship to other molecules What activity/demo does this fit with?
HYDROPHILLIC: Water loving
Ex: Water molecules attract other polar molecules
HYDROPHOBIC: Water “fearing”
Ex: water molecules repel non polar molecules – do not form hydrogen bonds
**Keep in mind that large molecules may have both hydrophilic and hydrophobic properties!
6. Make Chemical Reactions Happen:
Water is NEEDED for chemical reactions within the body
Most reactions take place in AQUEOUS solutions…”in water”
Water is a UNIVERSAL SOLVENT and due to its polar properties it has the ability to break apart or combine molecules
a. Dehydration Synthesis: Loss of water molecule resulting in a combination of molecules.
b. Hydrolysis: Addition of a water molecule results in the breaking apart of molecules.