The Chemistry of Life
Ch 2: Biology (Miller Levine Bee Book)
Sailors traveling long distances would sometimes become sick, their gums would bleed and tiny red bumps would appear on their skin.
Eventually, they would weaken and die.
This condition is called scurvy.
Brainstorm a list of possible causes for this condition.
Atoms - the basic unit of matter
- protons (positive)
- neutrons (neutral)
- electrons (negative)
2.1 The Nature of Matter
Elements
An element consists of only one type of atom:
Examples:
Carbon
Hydrogen
Oxygen
6 electrons in outer shell
6 protons
6 neutrons
Compounds
- consist of two or more elements
Examples:
Water (H2O)
Table Salt (NaCl)
Water Molecule�(also a compound)
The Periodic Table - shows elements arranged by � their atomic number
atomic number
Which letter on the diagram represents the:
1. Protons
2. Electrons
3. Neutrons
Quick Check
Chemical Bonds - hold together compounds
- ionic bonds involve the transferring of electrons
- covalent bonds involve sharing electrons
Water Molecule
What type of bond holds the water molecule together?
Interactions between atoms and molecules
- van der Waals forces � (feet of a gecko)
- hydrogen bonds � (water molecules)
Properties of Water
Water is essential to life on earth!
Discuss with your elbow partner why water is so important? Why do we need it? Be ready to share!
2.2 Properties of Water
1. Polarity
- water has a partial positive and negative charge
- water is a polar molecule
- forms hydrogen bonds
Hydrogen Bond
How many hydrogen bonds can you count?
2. Cohesion - water molecules stick together
- this creates surface tension
- how some insects walk on water!
3. Adhesion - water sticks to other things
This is what causes the curve in the tube
4. Heat Capacity
- amount of energy needed to change temperature
- water absorbs heat
The surface of this lake is frozen, but fish are still alive in the unfrozen area underneath the surface.
5. Universal Solvent
- many substances dissolve in water
Solutes - things that dissolve, like salt and Sugar
*Creates a solution
6. Occurs in 3 States
- gas (water vapor)
- liquid (pond water)
- solid (ice)
*Frozen water is less dense than liquid water
- so it floats!
Water in Living Things
- organisms are mostly water
- the body’s chemical reactions are dependent on water
Water droplets are shown on a leaf. This represents what property of water?
a) polarity
b) heat capacity
c) cohesion
d) adhesion
Quick Check
2.3 Carbon Compounds
- Organic compounds are chains of carbons
- Macromolecules are large molecules found in living things
- carbohydrate
- lipid
- protein
- nucleic acid
Carbohydrates
- monosaccharides: simple sugars � (glucose)
- polysaccharides (complex)
- glycogen in animals
- starch (plant storage)
- cellulose (plant structure)
Nucleic Acids
- information storage
- DNA
(deoxyribonucleic acid)
- RNA (ribonucleic acid)
Lipids -fats and oils
- saturated (solid)
- unsaturated (liquid) Example: Olive oil
- hormones
Glycerol
Fatty acids
Proteins
- made of amino acids
- joined by peptide bonds
- Example: Hemoglobin
2.4 Enzymes
- speed chemical reactions that take place in cells
- Lactase is the enzyme that helps us digest milk
- Lactose (milk) is broken down in simple sugars
Some people lack this enzyme and that makes dairy difficult to digest. What happens if someone is lactose intolerant and drinks milk?
Example of Enzyme Reaction
Enzyme
(Catalase)
Substrate
(Hydrogen Peroxide)
Products�(Water and Oxygen)
The reaction is: 2H2O2 → 2H2O + O2� hydrogen peroxide → water + oxygen
This is what causes hydrogen peroxide to bubble when you pour it onto a wound. The bubbles are oxygen!
Enzymes work best at OPTIMAL temperatures
This enzyme works best at what temperature?
What happens if the temperature is too hot?
pH refers to how acidic or basic something is. Enzymes have an optimal pH.
Basic
Acidic
Neutral