2. WATER
• Earth’s ability to support life is based on the presence of Water as a solvent
liquid water. It makes up approximately 60% of the human -Solvent for all polar molecules and ionic compounds, dissolves more
body and 60% - 70% of all life forms. than any other liquid.
-Acts as a “chemical wedge”; can break apart and form new bonds;
facilitates many chemical reactions in biological systems in the human
• A water molecule consists of two positively charged
hydrogen atoms and one negatively charged oxygen body.
atom. Water molecules are held together by weak attractive
Water as a temperature regulator
forces called hydrogen bonds.
-Water temperature changes slowly; no drastic changes.
-High boiling point (100 degrees Celsius)
Water as a lubricant
-A vital, natural lubricant.
-Humans need water to produce the bodily fluids that allow us to
blink, circulate blood, swallow, and do the horizontal monster mash.
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• H2O is a polar molecule because the electrons are unevenly
distributed meaning the hydrogen ends of the molecule have a
slight positive negative charge and the oxygen end has a mild
negative charge. This weak attraction is enough to create
hydrogen bonds, but a whole water molecule is electrically
neutral.
3. Acids, Bases, & Buffers
Acids, bases and buffers all have important roles in the
biological systems within the human body, with particular
regard to maintaining chemical balance.
Acids (substances with a pH lower than 7): essential to the
digestive system. Hydrochloric Acid in our stomach helps us
break down food particles so that nutrients can be extracted.
Bases (with a pH greater than 7): blood must maintain a pH
of about 7.35-7.45, (a slight base) in order for hemoglobin to
be carried.
Buffers are chemical combinations present throughout the
systems of the human body that keep pH levels regular.
Buffers resist changes in pH (from, for example, a poorly
balanced diet) because they can take up hydrogen or
hydroxide ions produced through the dissociation of water
molecules. (see below)
The scale used to measure the acidity or alkalinity of shows how
dissociated
substances is pH (0-14), 0 being very acidic and 14 hydrogen and
being very alkali. Water is considered neutral at about 7. hydroxide ions
can bond with
other chemicals
to form acids or
bases.
4. Carbohydrates
type structure examples
All carbohydrates contain hydrogen, oxygen and carbon. The
Glucose (pictured)
Monosaccharide
Ribose
3 main types of carbohydrates are monosaccharides,
(Simple sugars)
Fructose disaccharides and polysaccharides. (saccharide = sugar) The
CnH2nOn
Deoxyribose carbohydrates in one’s diet allow cells to produce energy.
Sucrose/table
Disaccharides
sugar(pictured) Dehydration synthesis - A simple process by which
Maltose monosaccharides become di- or polysaccharides:
(Double sugars)
Lactose
Dehydration (removal of water) occurs when two
carbohydrates are brought together to form a new
carbohydrate. Water is left over as a by-product of the
Starch
synthesis, taking a hydrogen (H) and a hydroxide (OH)
Polysaccharides Cellulose (pictured) from either carbohydrate.
(Complex sugars) Glycogen Hydrolysis is the reverse of this process in which water
is added to a compound in order to break it down.
Cellulose: Found
Starch: Storage only in plants - forms
form of sugar in cell walls and gives
plants. Helps maintain them their rigidity.
structural integrity. Glycogen: Storage Contains inra-
Contains double form of sugar in intermolecular
bonds. animals. Contains hydrogens bonds. An
double bonds. insoluble fiber.
Dehydration Synthesis
5. Proteins
Proteins are organic compounds made
Amino Group Side chain Main Functions of
up of one or several polypeptides.
Proteins
Amino acids (monomers) are
•Source of energy
bonded together in certain ways to
• Builds / repairs body tissues
form different proteins. There are a
(muscle, etc.)
total of 20 individual amino acids, all
• Makes up enzymes &
with a nitrogen-based amino group.
hormones
Peptide bonds, which form through
• Maintains healthy hair, nails,
dehydration reactions, link amino acids
skin
Carboxylic acid group. in a protein.
Structure
Primary: a sequence of amino acids held together by peptide bonds.
Secondary: forms as a result of weak attractive forces between adjacent amino
acids.
Tertiary: globular proteins that hold their shape due to disulphide bonds between
folded strands. Many enzymes have this structure.
Quaternary: made of several polypeptides coming together to form a larger
molecule. Hemoglobin has this structure and is made up of 4 polypeptides.
6. Nucleic Acids
Nucleotides (a type of monomer) form polymers called nucleic acids.
ATP: a single nucleotide
which acts as a “mobile energy
source” for all cells in the body.
Deoxyribonucleic
Acid DNA RNA Ribonucleic Acid
The genetic material itself involved in using genetic information
Double alpha helix structure Linear (single-stranded) structure
The nucleotides are made
The four types of The four types of
up of a 5-carbon sugar, a
nitrogenous bases in DNA nitrogenous bases in RNA
phosphate, and a nitrogenous
fall into two categories. fall into two categories.
base.
Purine bases Pyrimidine bases Purine bases Pyrimidine bases
• Adenine (A) • Thymine (T) • Adenine (A) • Uracil (U)
• Guanine (G) • Cytosine (C) • Guanine (G) • Cytosine (C)
DNA has a double helix
structure, consisting of a sugar-
phosphate backbone (purple),
held in helix formation by
complimentary base pairings (T-
A, C-G) and hydrogen bonding.
7. Lipids
Oils, fats, waxes, steroids and phospholipids are all classified as lipids.
Fats and oils (neutral fats) provide
energy storage. They consist of 3 Steroids
fatty acids attached to one glycerol “Circular fats”, steroids are structured very
molecule and are known as differently than other lipids. Rather than
Fatty acids are made triglycerides. Oils, liquid at room having a glycerol and 3 fatty acids, steroids
of long hydrocarbon temperature, store energy in plants, consist of four carbon rings with other
chains ending in an acid and fats, solid at room temperature do groups of atoms (OH-, etc.) added. Some Cholesterol
group. the same in animals. Fats and oils are common steroids in the human body are
not water soluble, and are stored in testosterone, estrogen, and cholesterol. Testosterone
body tissue.
There are two types Fatty acids
of fatty acid. Glycerol
Unsaturated Saturated
• Has some double • single bonds between Phospholipids
bonds between carbons, carbons allows for more A certain kind of fat that
allowing for less hydrogens to be bonded, has a phosphate
hydrogen atoms. Found saturating the carbons with group substituted for
in plant oils. Hydrogens hydrogen. Found only in one of the three fatty
can be added, making animal fats, which are solid at acids attached to the
glycerol molecule. A
them saturated. room temperature.
phospholipid molecule
consists of a polar
(hydrophilic) “head”
consisting of glycerol,
nitrogen phosphate
groups. and and non-
polar (hydrophobic)
“tail”, consisting of two
fatty acids.
9. Bibliography
In Class Notes
General & Human Biology: http://mhhe.com/biosci/genbio/espv2/data/cells/001/
index.html
Open School BC Biology 12 Course Resource: http://openschool.bc.ca/courses/
biology/bi12/mod1.html
Chemical Compound Outline (Part I): http://waynesword.palomar.edu/chemid1.htm
Kimball's Biology Pages:http: //users.rcn.com/jkimball.ma.ultranet/BiologyPages/
An On-Line Biology Book: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/
BioBookTOC.html
