ANAT41 – Lecture Notes
Chemistry
Chemical Level of Organization
Element - is a simple pure substance that cannot be separated into different substances
by ordinary chemical methods. The basic unit of an element is the atom.
Each element is written as a chemical symbol. What are the chemical
symbols for the main elements found in the human body?
Major Element
Oxygen
Chemical Symbol
O
C
Carbon
H
Hydrogen
N
Nitrogen
Atom - smallest unit of matter that retains the properties and characteristics of an
element.
The number of identified elements can be found on the periodic table.
How many elements are there?
Structure of an atom:
1. Proton - located in the nucleus of the atom, positively charged
2. Neutron - located in the nucleus of the atom, neutral in charge
3. Electron - located in shells around the nucleus, negatively charged
What does the atomic structure look like?
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ANAT41 – Lecture Notes
Chemistry
Ion - charged atom, either be negatively or positively charged
How does an ion become charged?
Molecule - A group of atoms (two or more) held together by chemical bonds
Ex. H2, O2, H20
Compound - substance that Is composed of two or more atoms from different elements
Ex. H20, C6H12O6
What is the difference between a molecule and compound?
Types of Chemical bonds:
1. Covalent - the formation of a molecule by the sharing of electrons. The combining
atoms do not lose or gain an electron.
Ex.
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ANAT41 – Lecture Notes
Chemistry
2. Ionic - the formation of a molecule that results from the force of attraction of
oppositely charged ions.
Ex.
3. Hydrogen - forms when a hydrogen atom with a slightly positive charge from a polar
covalent bond is attracted to an atom with a slightly negative charge, usually oxygen or nitrogen
Ex.
Which bond is the weakest?
Which bond is the strongest (hardest to break)?
How are bonds formed and broken?
1. Synthesis Reaction: anabolic reactions; occur when 2 or more atoms, ions or molecules
combine to form new and larger molecules
A + B  AB
A = atom, ion or molecule
B = atom, ion or molecule
AB = New molecule
2. Decomposition Reaction: catabolic reaction; molecules broken down into smaller parts
AB  A + B
3. Exchange Reaction: It consists of a decomposition reaction and then a synthesis to form
two new products.
AB + CD  AD + BC
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ANAT41 – Lecture Notes
Chemistry
4. Reversible Reaction: these reactions can go in either direction
AB  A + B
 breaks down
 forms a larger molecule
What is required or liberated when bonds are created or broken?
Energy - in the form of ____________
Metabolism = sum of all chemical reactions in the body.
There are two types: catabolism and anabolism
Two main classes of chemicals in the body:
1. Inorganic: usually lack carbon, simple and are held together by covalent or ionic bonds
2. Organic: always contain carbon, usually contain hydrogen and always have covalent bonds
What is the difference between the two?
Inorganic molecules




Water: most important Inorganic
molecule
When placed in water, dissociates
into…..
Acid: hydrogen ion and an anion
Base: hydroxide and a cation
Organic molecules

Carbohydrates

Proteins

Lipids

Nucleic Acids
Salt: an anion and cation, neither of
which is hydrogen or hydroxide
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ANAT41 – Lecture Notes
Chemistry
Solvent vs. Solute:
Water Is the most Important inorganic compound in our human bodies.
Properties that make water an Important part of our existence:
1. An excellent solvent
2. Participates in chemical reactions
3. Absorbs and releases heat very slowly
4. Requires a large amount of heat to change from a liquid to a gas
5. Lubricant
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ANAT41 – Lecture Notes
Chemistry
What do acids and bases have to do with pH?
What is the pH of an acidic solution?
What is the pH of a basic solution?
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ANAT41 – Lecture Notes
Chemistry
Organic molecule
Composition
(elements)
Carbon, Hydrogen,
Oxygen
Monomer (building
blocks)
Monosaccharide
Examples
Proteins
Carbon, Hydrogen,
Oxygen
Amino Acids
Keratin, Antibodies,
Muscle, Collagen
Lipids
Carbon, Hydrogen,
Oxygen, Phosphate
Glycerol backbone, 3
fatty acids
Fats, Oils, Steroids,
Cholesterol
Nucleic Acids
Carbon, Hydrogen,
Oxygen, Nitrogen
Nucleotides
DNA, RNA, ATP
Carbohydrates
Sugars, glycogen,
starches, cellulose
We will draw the structures together. Your book also has figures you can refer to.
Carbohydrate Structure:
Protein structure:
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ANAT41 – Lecture Notes
Chemistry
Lipid structure:
Fat
Phospholipid
Cholesterol
Nucleic Acid structure:
DNA
RNA
ATP
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