THE CHEMICAL LEVEL OF ORGANIZATION
Atoms
Molecules
Organelles
Cells
Tissues
Organs
Systems
Organisms
a. CHEMICAL LEVEL

Includes atoms (smallest unit of matter) and molecules (atoms joined
together, such as DNA)
b. CELLULAR LEVEL
 Molecules combine to form cells (basic structural and functional units of
organism; smallest living units in the human body)
c. TISSUE LEVEL
 Tissues: groups of cells and the materials surrounding them that work
together ti perform a particular function
4 Basic Types: Epithelial, Connective, Muscular, Nervous

d. ORGAN LEVEL
 Different tissues are joined together
 Skin, bones, stomach, heart, liver, brain,...
 Example: Stomach
o
o
o
Outer Covering: Serous Membrane (layer of epithelial and
connective tissue)
Underneath is the Smooth Muscle Tissue Layers
Innermost Lining: Epithelial Tissue Layer
e. ORGAN-SYSTEM LEVEL
 Related organs with a common function
f. ORGANISMAL LEVEL
 All the parts of the human body functioning together
ATOMS


The symbol of an element
indicates 1 atom of that
element
A number preceding the
symbol of
an
elements
indicates more than 1 atom of
that element
MOLECULES
 A
numerical
subscript
following the symbol of an
element indicates the number
of atoms of that element in a
molecule
REACTIONS
 Chemical


reactions
are
represented
by
chemical
equations
Reactants:
starting
substances
Products: ending substances
IONS
 Indicated by a superscript
plus or minus sign
following the symbol of
an element
Chemical Reaction: occurs when new bonds
are formed or old bonds are broken
1. Decomposition Reactions
(Catabolism)
2. Synthesis Reactions (Anabolism)
 Combination of molecules to form
even larger products (formation of new
chemical bonds)
3. Exchange Reactions
 parts of the reacting mlecules are
shuffles around
products
to produce new
Glucose and Fructose are both
monossaccharide
Sucrose is a disaccharide
*oxygen (delivers energy all throughout the body) level should not be lower than 95%
*shortage in oxygen can cause stroke (nervous or heart disorder)
*Na and Cl are good electrolytes
a. Water
o most abundant (plasma in blood 90% water)
o help control normal body temperature
o takes part in photosynthesis and respsiration which produces energy
b. Carbon Dioxide (CO2)
o
o
o
o
waste product of cellular respiration
source of the element carbon
convert radiant energy into usable chemical energy (glucose)
too much can cause acidity/malfunctioning
c. Molecular Oxygen (O2)
o 21% content in the atmosphere
o Convert chemical energy (food) into ATP
d. Mineral Salts/Electrolytes
o Essential for the survival and functioning of the body’s cells
o Calcium (Ca+): muscle contraction, nervous transmisson, building strong
bones
o Chloride (Cl2): nervous transmission
o Sodium (Na+)and Potassium (K+): muscle contraction and nervous
transmission
o Phosphate (PO4): produces high energy molecule ATP
e. Ammonia (NH3)
o From the decomposition of proteins (via the digestive process and
conversion of amino acid in cellular respiration to ATP molecules)
o Nitrogen is the important element
o Through enzymes, the liver converts the toxic ammonia to a harmless
substance (urea)
f. Carbohydrates (C6H12O6)
o Ribose and deoxyribose (parts of the DNA and RNA)
o Energy storage (sugars, starch, glycogen)
o Cell strengthening (cellulose and chitin)
g. Lipids
o Insoluble in water
o Fats, phospholipids, steroids, prostaglandin
h. Proteins
o Composed of C, H, O, and N covalently bonded
o Part of cell membranous structures: plasma membrane, nuclear membrane,
endoplasmic, reticulum, and mitochondria
o Enzymes
o Antibodies
o Source of energy converted to ATP
i. Nucleic Acids
o DNA and RNA
o C, H, O, N, P
j. Adenosine Triposphate
o Used to run the cell and to perform activities (repair, reproduction,
assimilation, and transport of materials across cell membranes)
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
Excessive hydrogen atoms can disrupt cell and tissue functions
pH: measure of hydrogen ion concentration
expresses the acidity and basicity of a solution
normal pH of blood: 7.35 – 7.45
Acidosis: abnormal physiological state caused by low blood pH
Alkalosis: abnormally high pH
Blood pH above 7.8 causes uncontrollable and sustained mucle contractions


Low pH = more acidic
High pH = more alkali
Buffers: stabilize the pH of a solution (by removing/replacing H+)
Buffer Systems: involve a weak acid and its related salt (which function as
a weak base)
Buffer and buffer systems in body fluids help maintain the pH withing normal limits
(ex: use on antacid)



Long chains of carbon atoms linked by covalent bonds (forming additional
covalent bonds with H+ or O2 atoms, and less commonly with N2, P, S, Fe or
other elements)
 Macromolecules: fats/lipids, carbohydrates, proteins, nucleic acids
(important in metabolism;source of energy)
 Each macromolecule is made up of monomer subunits bonded to other
identical molecules to form a polymer (joined throug dehydration synthesis
reactions; released through hydrolysis reactions)
 Carbohydrates: release monosaccharides
 Lipids (fats): release fatty acids and glycerol
 Proteins: release amino acids
 Nucleic Acids: release nucleotides
a. CARBOHYDRATES
 Contain C, H, O (ratio – 1:2:1)
 Account for less than 1% of total body weight
 all
carbohydrates
(except
monosaccharides) must be broken apart
through hydrolysis before they can provide
useful energy
 artificial sweeteners: cannot be broken
down in the body or used in insignficant
amounts
 Glycogen (animal starch): does not dissolve
in water or body fluids; made and stored in
muscle cells
 When muscle cells have high demand for
glucose: glycogen molecules are broken down
 When the need is low: cells absorb glucose from the bloodstream and rebuild
glycogen reserve
b. LIPIDS
 12-18% of the total body weight of adult men
 18-24% for adult women
 Important as energy reserves (provide twice as much energy as
carbohydrates)
 When the supply exceeds the demand for energy: excess is stored in fat
deposits
 Fat substitutes: provide less energy but have the same taste and texture as
the fats found in many foods
 5 Classes
1. Fatty Acid
 Saturared
 contains only single covalent bonds
 whole milk, butter, eggs, beef, pork, and coconut and
palm oils
2.
3.
4.
5.
 too much can cause cardiovascular disease
(hypertension, atherosclerosis: narrowing of blood
vessels caused by the plaquing of fatty acids)
 solid at room temperature
 Unsaturated
 Healthy
 Sunflower, corn, and fish oils
 Liquid at room temperature
Eicosanoids
 Derived from arachidonic acid (fatty acid that must be
absored in diet because the body cannot synthesize it)
 Leukotrienes
 Prostaglandins (Local Hormones): coordinate or direct local
cellular activities
Glycerides
 Triglycerides (Triacylglycerols/Neutral Fat): energy source,
insulation, protection
Steroids
 Differ in the functional groups that are attached to this basic
framework
 Cholesterol: contained in plasma membrane
 Steroid Hormones: Involved in the regulation of sexual
function (corticosteroids)
 Bile Salts: steroid derivatives, required for the normal
processing of dietary fats
Phospholipids and Glycolipids
c. PROTEINS
 Most abundant organic molecule in the human body (20% of the total body
weight)
 Amino Acids: simple organic compounds (monomers) that combine to form
proteins (polymers)
 Functions:
 Structural Proteins: support
 Contractive Proteins: movement
 Transport Proteins: transport
 Buffering
 Enzymes: metabolic regulation
 Protein Hormones: coordination and control
 Special Clotting Proteins: defense
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Dehydration Synthesis: link
two representative amino
acids (glycine and alanine)
*chain can be lengthened by the
addition of more amino acids
producing tripeptide
*familiar proteins: hemoglobin (in
red blood cells), collagen (in skin,
bones, and muscles), and keratin
(in fingernails and hair)
SEQUENCE OF AMINO ACIDS
DETERMINE THE PROTEIN’S
SHAPE;
ITS
SHAPE
DETERMINES ITS FUNCTIONAL
CHARACTERISTICS
Primary
Structure:
determined by its amino acid
sequence
Secondary
Structure:
determined by hydrogen bonds
between amino acids (that
cause the protein to coil into
helices or pleated sheets);
proteins
become
nonfunctional once H-bonds
are destroyed
Tertiary Structure: secondary
folding
(caused
by
interactions within peptide
bonds and between sulfur
atoms of different amino acids)
Quaternary Structure: determined by the spatial relationships between
individual units
Enzyme Function
 Most important of all the body’s proteins
 Catalyze the chemical reactions that sustain life
 Substrates: reactants in enzymatic reactions
 Active Site: special region of the enzyme where substrates bind
before they can function as calayst; shape is determined by the
tertiary or quarterynary structure


 Temperature and pH affect enzyme functions
 as temperature arises, protein shape changes and enzyme
function deteriorates
 Enzymes are sensitive to changes in pH
Pepsin: enzyme that breaks down food proteins in the
stomach works best at a pH of 2.0
Trypsin: works only in an alkaline environment, with an
optimum pH of 7.7
Glycoproteins: may function as enzymes, antibodies, hormones, or protein
components of plasma membranes (identify normal from abnormal cells)
Proteoglycans: bind adjacent cells together and give tissue fluids a viscous
consistency
d. NUCLEIC ACIDS
 Store and process information at the molecular level inside cells
e. ADENOSINE TRIPOSPHATE
 Phosphorylation: process of attaching a phosphate group to another
molecule
 most important method of storing energy in our cells: conversion of ADP to
ATP
 most important method of releasing energy: the breakdown of ATP to ADP