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All organisms contain essential elements.
About 25 of the 92 natural elements are known to be
essential to life.
 carbon (C),
 oxygen (O),
make up 96% of living organisms.
 hydrogen (H)
 nitrogen (N)
 Phosphorus (P),
 sulfur (S),
 calcium (Ca),
 potassium (K)
The remaining less than 4%
Trace elements: are those required by an organism in only
minute quantities.
Boron, chromium, cobalt, copper, fluorine, iron, manganese,
molybdenum, selenium,silicon, vanadium and zinc
Chemical content of human body
In chemistry, molecules with a backbone of carbon that also contain
hydrogen are called organic molecules. The other atoms and molecules
necessary for life are inorganic.
carbohydrates, proteins, lipids and nucleic acids, our vitamins are
considered to be organic.
Water, oxygen, carbon dioxide and the minerals needed to sustain life
are inorganic.
Which Properties of Carbon make it important for the living?
1) Carbon is one of the atoms (elements) that forms covalent
bonds to become stable.
Each carbon atom makes 4 bonds, in either chains, branching
chains or rings of linked carbon atoms. This diversity in bond
formation defines different function in life
Different bonds in hydrocarbons
Single bonds and chain
Chain and branched bonds
Double bonds in different
location
Ring shape with single or
double bonds
2) Hydrocarbons, may have functional groups
Functional groups also create diversity of molecules function
just like diversity in bond formation.
Examples of Functional Groups
Hydroxyl group - OH
Amino group - NH3+
Carboxyl group - COOH
Phosphate group - PO3Sulfhydryl group - SH
3) Hydrocarbon variations that differ only in the
arrangement of atoms are called isomers. Isomers are
very important in biology. There are three types of
isomers: structural, geometric and enantiomers.
Structural isomers vary in their covalent bonding
arrangement.
Geometric isomers share common covalent bonding, but have different
shapes. The differing shape of geometric isomers can dramatically affect
their biological function. (This is sometimes called the cis-trans
difference.)
Enantiomers are isomers that have the same molecular formula but
are mirror images of each other.
 All living organisms are based on the carbon
atom.
 Carbon atoms continually move through living
organisms, the oceans, the atmosphere, and the
crust of the planet. This movement is known as the
carbon cycle.
HOW CARBON RECYCLE?
Atmosphere
Photosynthetic organisms
Soil and oceans and burning
organic material
Gas form back to atmosphere
ORGANIC MOLECULES OF ORGANISMS = MACROMOLECULES
All organic compounds of the livings are responsible for such things as:
 
Fuel (energy to do cell work and keep us alive)
 
Structure
 
Metabolism
 
Fuel Storage
 
Genetic Information
The cells and tissues of virtually all organisms are made up of the same
basic molecules. Many of these are substances with which we are familiar:
carbohydrates, lipids, proteins and the nucleic acids. They are known as
MACRO MOLECULES (large molecules).
the chemical processes by which large molecules (polymers or
macromolecules) are built from smaller molecules (often called monomers
or subunits) that have a common structure.
Most of our biological molecules are assembled or broken down using the
same types of chemical reactions.
Macro molecules or polymers: How they form and how they break down?
•  formed by joining smaller (monomers) molecules into chains called
polymers
• Greek “polys “– many, “meros” – part
•  since during joining of monomers water molecules are released the
reaction called “dehydration” reaction
monomer
monomer
monomer
monomer
monomer
monomer
monomer
Hydrolysis
dehydration
monomer
monomer
monomer
monomer
monomer
POLYMER
•  polymers break down to monomers by using water, reaction called “Hydrolysis”
•  Greek “hydro” – water, “lyse” - break
• two outcomes
1. provides energy
2. provides monomers (building blocks) needed for an organism to
synthesize its own macromolecules
Carbohydrate (sugar) types:
All carbohydrates are composed of one or more monosaccharides.
 The simple sugars are formed from one (monosaccharide) or
two monosaccharides (called disaccharides), and
 few monosaccharides ( called oligosaccharides)
the complex carbohydrates (polymers) are formed from long chains
of monosaccharides, are called polysaccharides
Carbohydrate Functions
• Basic energy source (fuel) for virtually all living organisms
• Structural molecules, especially of plants, most fungi and arthropods (e.g.,
cellulose, chitin)
• Fuel reserve molecules (e.g., starch, glycogen)
Carbohydrate structure
•  their monomers are monosaccharides Chemically, contain:
Carbon, Hydrogen, Oxygen
• The ratio of atoms in a monosaccharide is: (CH2O)n n= 3-6
• The functional groups of monosaccharides are: –OH “Hydroxyl”
=O “Carbonyl”
•  examples of 6 carbon monosaccharides: glucose, fructose, galactose
(main energy source of cell, fruit sugar and milk sugar respectively)
Disaccharides and polysaccharides
• Disaccharides are 2 monosaccharides joined by a dehydration
synthesis, which is the removal of a water molecule. Examples
of common disaccharides are sucrose, lactose, and maltose
Sucrose= table sugar (glucose+fructose)
Lactose= breast milk sugar (glucose+galactose)
Maltose= formed by breakdown of starch in animals intestine
(glucose+glucose)
Oligosaccharides
• Humans cannot digest oligosaccharides, but the bacteria in our
intestines can.
•  they are formed from 3-10 sugar subunits
• also found as part of glycoproteins and play a role in cell
recognition/identity.
•  may be linked to a lipid molecule to form a glycolipid.
In water glucose is constantly bending and forming itself into two different
ring configurations millions of times a second. In both cases the oxygen at
the end of the straight chain attaches itself to the carbon on opposite end.
The hydrogen jumps off the oxygen and turns the double-bond oxygen (=O
into OH [hydroxide]). Sometimes this OH will end up oriented downward
(alpha-glucose), and other times the OH will be oriented upward (betaglucose).
Polysaccharides
Polysaccharides are formed by joining 100-1000
monosaccharides, by a dehydration synthesis.
The common stored polysaccharides are:
• Starch (in plants)
• Glycogen (in animals)
The common structural polysaccharides are:
•  Chitin
•  Cellulose
Both starch and glycogen are polysaccharides of glucose.
Starch is a very long coiled, unbranched or branching chain,
with about 1000 glucose molecules in any branch.
Glycogen branches frequently (about every 10 or so glucose
units) and is more easily broken down. Starch and glycogen are
important fuel storage molecules.
1-4 α D glycosidic linkage
1-4 β, D-glycosidic linkage
Cellulose
• Long chains of glucose
• Cellulose is for most living organisms, non-digestible. Few
organisms have the enzyme needed to break down cellulose.
Cellulose and related compounds form most of what we call
fiber.
Chitin
• Long modified glucose chains, in which a nitrogen-containing
functional group replaces one of the hydroxyl groups on each
glucose subunit.
• Chitin forms the exoskeleton of many invertebrate animals
(mostly arthropods)
Functions of Lipids
1. long-term energy (fuel) storage (2X that of carbohydrates)
2. insulation
3. Cushion
4. Structural
5. Many hormones (regulatory)
Structure of Lipids
• carbon
• hydrogen
• oxygen
However – the proportion of oxygen is low, so lipids are mostly
hydrocarbons
• The chemical structure of fats and oils, the most common lipids,are
based on fatty acid as building blocks and an glycerol (type of alcohol)
• The terms fats and oils are
Fats are "hard" or solid at room temperature, found in animals
Oils are liquids at room temperature, found in plants
•  all lipids are very hydrophobic molecules (fear water, cant dissolve in
water)
Major types of Lipids
1. Triglycerides commonly known as the fats and oils
2. Waxes
3. Phospholipids
4. Sterols (or steroids)
5. Terpenes
Structure of Fats and Oils
(the Triglycerides)
 One molecule of glycerol +
3 fatty acid tails finish with
carboxyl group
 The double bonds in carbon
atoms of fatty acids
determine the characteristics
as saturated or unsaturated
triglycerides
carboxyl
Fatty acids are chains of hydrocarbons 4—
22 carbons long with the carboxyl
functional (acid) group at end-----COOH
Each carbon within the chain has 2 spots
for bonds with hydrogen
• If each carbon has 2 hydrogens the
fatty acid is saturated (no double bond)
•  If two carbon atoms are double bonded,
so that there is less hydrogen in the
fatty acid, it is mono-unsaturated (single
double bond)
Kink
If more than 2 carbon atoms are
unsaturated, the fatty acid is polyunsaturated ( many double bonds)
WHAT MAKES THEM LIQUID or SOLID?
The more polyunsaturated the lipid the more liquid it is in cold
temperature. Therefore oils are rich in poly-unsaturated fatty
acid tails and thus they are liquid. Fats are poor in polyunsaturated fatty acid tails thus they are solid at cold
temperature.
The length of fatty acid chain also affect the triglycerides
solid or liquid state. The shorter the fatty acid chain the
more liquid (lower its melting point), the longer the fatty
acid
Phospholipid
chain the more solid at cold temperature
PHOSPHO-LIPIDS
Phospholipids are composed of a glycerol molecule with two
fatty acids and a phosphate-containing compound attached to
the third carbon.
Phospholipids are structural molecules forming the major
component of all membranes of cells.
Phosphate group type
Glycerol
Fatty acid chain
(hydrocarbon)
Various phospholipid types are created by
different functional groups found at the phosphate
group
phospholipid structure is highly amphipathic (both hydrophobic &
hydrophilic part containing molecule) , ideal for the cell membrane
structure that can make micelle formation or bilayer structure in
water
Hydrophilic portion in the phosphate region
Hydrophobic portion in the fatty acid tails
Bilayer structure
Double layer
single layer
Phospholipids also make excellent emulsifiers and are used in a number
of food and household products.
WAXES
Do not contain glycerol only has 2 fatty acid tails attached to each
other
 They are extremely hydrophobic
 They have a rigid, solid structure at "normal" temperatures
 They provide waterproof, temperature protective layer (ex: fruit
skins, fur of animals, plant leaves, ear wax,)
STEROIDS
 Unlike all other lipids they do NOT contain
fatty acid tail. Only contains 4 hydrocarbon
rings
 Although rarely found in plants, certain
plant steroids, such as the soy flavinoids, are
similar in structure to the estrogen
hormones of animals.
 major sex hormones, Vitamin A & D
drived from them
Water repellent effect of wax on skin
Orange skin
PROTEINS (Polypeptides):
Amino acid structure
-central carbon atom
surrounded by
-amino group
-carboxyl group
-single hydrogen
-variable R group
- Polypeptide
several amino acids join by
peptide bonds dehydration
reaction.
Central carbon
Variable group
hydrophobic
hydrophilic
acidic
basic
 The structure of the R group dictates the chemical properties of the
amino acid.
 R-group can be as simple as Hydrogen atom or a very big molecule.
 According to R-groups amino acids classified as:
1. nonpolar (hydrophobic) (7 of them)
2. polar (hydrophilic) (8 of them)
3. acidic (2 of them)
4. basic (3 of them)
 The combination of 20 different amino acids determines the sequence
and shape of the protein.
ex: aa1+aa2+aa3+aa4 (is one type of protein) whereas aa1+aa3+aa4+aa2 is
another type
 Protein structure can be in 4 different conformation
1. primary structure= chain of amino acids
2. secondary structure= alpha helix or beta sheet
3. Tertiary structure= folding of helices due to interactions
between adjacent R-groups
4. Quaternary structure= combination of several polypeptides
Active and
functional proteins
are always in
secondary or
tertiary structure
peptide bonding
Hydrogen bonding
Bonding types between
R groups of amino acids
Examples of certain proteins
and their structure
Wool, skin, hair, nail = secondary
structure
Uncooked egg
cooked egg
Enzymes and most other functional
proteins like albumin in egg white=
tertiary structure
Haemoglobin (blood protein that carry
oxygen) = quarternary structure
Factors that affect the structure of proteins and thus make them nonfunctional
--pH change
-- high temperature
---heavy metals
--- high salt
--- organic solvent
Change in the structure of protein
that destroys its function is called denaturation
How do polypeptides vary?
1.  Number of amino acids in the chain: 50—1000
2. Which kinds of amino acids there are in the chain (of the 20
types)
3. How many of each kind of amino acid
4. sequence of amino acids
NUCLEIC ACIDS
Two essential functions
1. information storage
• DNA, RNA
2. store and transfer energy
• ATP
Nucleotides Are the Monomers That
Create Polymers of DNA and RNA
• Nucleotides have 3 parts
1. sugar (pentose; 5 carbon sugar)
• deoxyribose in DNA
• ribose in RNA
2. Phosphate
3. Nitrogen-containing base
• A,C,G,T in DNA
• A,C,G,U in RNA
ATP, GTP, TTP, CTP, UTP
5 possible nucletides
They always in tri-phosphate form
as a monomer
DNA
-nucleotides connected by phosphodiester bonds
- double helix: 2 polynucleotide strands connected by hydrogen bonds
-polynucleotide strands are complementary
-genetic information is carried in the sequence of nucleotides
2 PPi
Hydrogen bonds
joins the bases of
the two antiparallel
(5’-3’ and 3’-5’)
strands of DNA
Double helix is an antiparallel strands
5’
3’
A – T (2 Hydrogen
bonds)
C- G (3 hydrogen
bonds)
3’
5’
RNA
-contains ribose instead of
deoxyribose
-contains uracil instead of
thymine
-single polynucleotid strand
-functions:
-read the genetic
information in DNA
-direct the synthesis of
proteins
Functions of Nucleotides
 Components of nucleic acids (which are long chains of
nucleotides)
 Energy carrier molecules (ATP)
 Energy transport coenzymes (NAD+, NADP+, FAD+)
 Chemical intracellular messengers
Functions of Nucleic Acids
 Storage of genetic information (DNA)
 Transmit genetic information from generation to generation
(DNA)
 Transmit genetic information for cell use (RNA)