Unit 1:
The Chemical Basis of Life
Refresher from Chem 20
1. Atoms:
 All matter has mass and takes up space
 All matter is composed of atoms
 Atoms are composed of three particles:
 Proton (+)
 Neutrons (no charge)
 Electrons (-)
1. Atoms:
 Nucleus of the atom is made of protons and neutrons
 Number of protons and electrons in an atom are the
same making the charge neutral
 Electrons circle the nucleus at different energy levels
to form an energy cloud
2. Elements
 An element is a substance composed of only one type
of atom
 Every atom in the element has the same number of
protons
 Isotopes occur when atoms of the same element have a
different number of neutrons
3. Molecules
 Molecule: when atoms join with other atoms of the
same or different elements
 Stable molecules are created when outermost energy
levels are completely filled
 Covalent Bonds: the forces involved in the sharing of
electrons to fill up an energy level
3. Molecules
 Bonds are held together by energy and when broken
that energy is released
 Weakest chemical bond is hydrogen because it has
only one electron
4. Compounds
 Compounds: substances composed of different kinds
of atoms chemically bonded together
 There are two main types of compounds:
 Inorganic compounds
 Organic compounds
4. Compounds
 Inorganic Compounds:
 contain no carbon
 Only a single carbon atom per molecule
 Contain energy that is not useful for organisms
4. Compounds
 Organic compounds:
 Built with long carbon-to-carbon chains
 Large molecules containing stored energy
 Energy can be used by organisms
 Ex:



CHO’s,
Proteins,
Lipids
5. Chemical Reactions
 Chemical Reaction: results from rearranging atoms
and molecules of the materials involved
 Ex: burning wood adds oxygen to the wood substances
5. Chemical Reactions
 Reactions can be written as chemical equations
 Reactants: beginning substances
 Products: end of reaction
 Law of Conservation of Mass: same number of
atoms at the beginning and the end of a reaction
 Energy is either required or produced when a reaction
occurs
6. Ions
 Ions: atoms that gained or lost electrons have an
imbalance of charged particles
 Positive Ions: atoms that donate electrons have an
excess of positive charge
 Negative Ions: atoms that accept electrons have an
excess of negative charge
 Ionic bonds form when electrons are transferred
7. Acids and Bases
 Water is made of 2 H atoms and 1 O atom
 A hydrogen atom breaks away from water molecule:
 Positive hydrogen ion
 Negative hydroxide ion
 Neutral solutions have the same number of hydrogen
and hydroxide ions
7. Acids and Bases
 Water is made of 2 H atoms and 1 O atom
 A hydrogen atom breaks away from water molecule:
 Positive hydrogen ion
 Negative hydroxide ion
 Neutral solutions have the same number of hydrogen
and hydroxide ions
7. Acids and Bases
 Acids: concentration of hydrogen ions >
concentration of hydroxide ions
 Have a sour taste... Lemon juice
 Basic: concentration of hydroxide ions >
concentration of hydrogen ions
 Ammonia, soap, oven cleaner
 pH scale 1-14
 1-6 Acids
 7 Neutral
 8-14 Basic
Carbohydrates
 These are composed of carbon, hydrogen, and oxygen
with the ratio of H:O=2:1
 Monosaccharides (C6H12O6) are called simple sugars
because they are made of only one sugar unit.
 Glucose is formed by plants during photosynthesis and
is the form of energy most easily used by cells.
 Monosaccharaide’s link together to form other types of
sugars
Carbohydrates
 Disaccharides (C12H22O11 ) are called double sugars
because they are formed when two monosaccharides
join together.
 Sucrose is made when a glucose and a fructose are joined
together.
 Whenever monosaccharides link together, a molecule of
water is released. This is called a dehydration reaction.
 Polysaccharides (C6H12O6)n are called many sugars
because they are formed when three or more
monosaccharides are linked together.
 4 calories per gram
How to Identify Carbohydrates
Only carbon’s, hydrogen’s, and oxygen’s
2. Twice as many H’s as O’s
3. Dehydration reaction has H2O as a product
4. Hydrolysis reaction has H2O as a reactant
5. The names end in ‘ose’
Lab Tests:
6. Benedict’s solution changes from blue to a variety of
other colors to indicate percentage of sugar
7. Iodine turns blue black to indicate starch
1.
Examples of Charbohydrates
 Glucose
 Sucrose
 Starch
 Cellulose
 Glycogen
 Chitin
Diagrams of Charbohydrates
Proteins
 These are composed of carbon, hydrogen, oxygen,
and nitrogen ( and sometimes sulphur)
 Built from a combination of twenty subunits called
amino acids
 The long chains (thousands of subunits) are called
polypeptide
 Green plants can synthesize all amino acids from simple
materials
 Animals cannot so they must get them from their diet
Proteins
 The particular combination of amino acids and the
3D folded shape it forms determines the function
of the protein.
 Important in living organisms because each type of
chemical reaction is controlled by a different type of
enzyme, which is formed from proteins
 Enzymes are complex proteins that cause a specific
chemical change in all parts of the body.
 The production of many different enzymes makes
thousands of chemical reactions
 4 Calories per gram
How to Identify Proteins
Must contain ‘N’
2. Sometimes contains ‘S’
3. Most labeled molecules end in ‘ine’
Lab Test:
4. The Bluret Test indicates peptide bonds when color
changes from blue to pink purples
1.
Examples of Proteins
 hair
 Webs
 Nails
 Scabs
 Steak (animal flesh)
 Blood cells
 Milk whey
 Enzymes
 Silk
 hormones
Diagrams of Proteins
Lipids
 These are oily or waxy substances that are
composed of carbon, hydrogen, and oxygen but
the ratio of H:O is always greater than 2:1
 Fats are made of two types of lipid building blocks:
 Glycerole which is a single sugar
 Fatty acids which are chains of carbon and hydrogen
with an acid grouping on one end
 Different fatty acids produce different lipids.
Lipids
 Lipids can be grouped into:
 Fats (animals)
 Oils (plants)
 Waxes (animals & plants)
 Generally fats are used as a concentrated source of
stored energy but can also be found in cell
membranes and as cushions around body organs.
How to Identify Lipids
Only carbon’s, hydrogen’s, oxygen’s but more than
double H’s than O’s
2. Several carbons with double bonds
Lab Test:
3. Sudan IV solution identifies most lipids with a color
change from pinks to reds
4. Translucence test indicates lipids by making
untreated paper to transmit light
1.
Examples of Lipids
 Fats:
 Margarine
 Butter
 Lard
 Blubber
 Oils:
 Canola oil
 Flax oil
 Vegetable Oil
 Waxes:
 Bee wax
 Ear wax
 Cuticle on leaves
Diagrams of Lipids
Nucleic Acid
 Another important group is nucleic acids (DNA, RNA)
 They are part of chromosomes and the reading of
chromosomes