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CHEMISTRY OF LIFE
Nature of matter
 Matter: Anything that occupies space & has
mass.
 Everything in the universe is made of mass.
 Atom is the smallest unit of matter that cannot
be broken down by chemical means.
 Atoms typically have 1 electron for each proton,
so they are neutral (no electrical charge)
3 Basic Particles of An Atom:
 Particle
 1. Proton
 2. Neutron
 3. Electron
Charge
Location
Positive (+) Nucleus
neutral (0) Nucleus
Negative (-) Electron Cloud
 The electrons are located in energy levels
located outside of the nucleus where the
electrons can move (electron cloud).
 Level
 1
 2
 3
Electrons possible in each
level
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Element is a substance made of only 1 kind of
atom, and it is a pure substance.
 Four elements that make up 96% of the human
body:
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1.
2.
3.
4.
Carbon
Hydrogen
Oxygen
Nitrogen
Atoms can bond together:
 A compound is formed when outer electrons are
attracted, shared, or transferred from one atom
to another atom in order to fill the outer
electron levels.
 Ex: Na+ + Cl- → NaCl (table salt)
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 A force that joins atoms is called a bond.
 There are 2 types of bonds:
 1. Covalent bonds
 2. Ionic bonds
 Ionic and covalent
compounds are alike in
that they both fill outer
electron levels.
 1. Covalent Bonds are created when 2 or more
atoms share electrons and form a molecule.
 Molecules are held together by covalent bonds.
 Example: H2O, CO2, and O2
 All organic compounds are held together by covalent
bonds.
 Molecules with an unequal distribution of electrical
charge, such as water molecules, are polar
molecules.
 Water has a positive charge on one end and a
negative charge on the other. Because of its uneven
charge, water is a polar molecule.
 A hydrogen bond
is a weak chemical
attraction between
polar molecules.
 2. Ionic Bonds are formed by the electrical
attraction between oppositely charged ions.
 Ion is a charged atom or molecule.
 Ions have an elec-
trical charge because
they contain an unequal number of electrons and protons.
Ionic Bonds Cont.
 An atom that has lost electrons is positively
charged.
 An atom that has gained electrons is negatively
charged.
 Ions or opposite charges may interact to form an
ionic bond.
 Example of an
ionic bond:
Na+ + Cl- = NaCl
Water and Solutions
 Water is an inorganic substance which means it is not made
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
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from carbon or living things.
Water is composed of 1 atom of oxygen and 2 atoms of
hydrogen.
Water molecules are linked by hydrogen bonds.
This causes water to heat up
and cool down slowly.
Water, which is essential for
life, stores heat efficiently and
binds to itself and other substances.
The most abundant inorganic
substance in a cell is water.
The hydrogen bonds between water molecules cause
the cohesion of liquid water. Cohesion is an
attraction between substances of the same kind.
Because of cohesion, water and other liquids form
drops and thin films. The thin films allow some
insects to stand on the surface of water because
water is cohesive and adhesive. This attraction
between water molecules (to itself) causes a
condition known as surface tension.
 Water molecules are also attracted to many other
polar substances.
 Adhesion is an attraction between different
substances. Because water stick to solids
(adhesion), water has the property of capillarity.
 Capillarity is the ability to spread through fine pores
or to move upward through tubes (such as the stem
of a plant) against the force of gravity. The
attraction of water to the walls of the tube sucks the
water up more strongly than gravity pulls it down.
 Water dissolves many substances:
 Due to water’s polar nature (uneven charge),
water makes a good solvent, pulling apart other
molecules. Nonpolar molecules do not dissolve
well in water. When nonpolar substances, such
as oil are placed in water, the oil forms lumps or
beads in water.
Nonpolar molecule
and water
Polar Molecules
and water
High Specific Heat
 The ability of water to stabilize temperature
depends on its relatively high specific heat.
 The specific heat of a substance is defined as the
amount of heat that must be absorbed or lost for 1
g of that substance to change its temperature 1 C.
 The specific heat of water is 1.00 cal/g C.
 Compared with most other substances, water has an
unusually high specific heat.
 Because of high specific heat, water will change its
temperature less when it absorbs or loses a given
amount of heat.
Acids and Bases:
 pH is a measure of how acidic or basic (alkaline) a solution is.
A change of one pH unit reflects a 10X change.
 The pH scale ranges from 0-14 and is used to measure pH.
 An acid is any substance that forms hydrogen ions (H+) in
water.
 This solution contains more H+ (hydrogen) ions and has a pH<7
 Sour and corrosive

Tend to burn

Turn litmus paper red

Examples: battery acid, sulfuric acid, stomach acid
Acids and Bases
 A base (alkaline) is any
 substance that forms OH(hydroxide) ions and
has a pH>7
 Are bitter and feel slippery
 Turn litmus paper blue
 Examples: soaps,
household cleaners
 A pH of 7indicates a
neutral between
acidic and alkalinity.
Chemistry of cells
 Organic compounds contain carbon atoms that are
covalently bonded to other elements, typically
hydrogen, oxygen and other carbon atoms.
 All organic compounds contain the element carbon.
 Carbon is the essential element that all life depends on.
 Carbon can form up to 4 covalent bonds with other
molecules.
 Its nature allows the ability to form straight chains,
branched chains, and rings.
 Carbon’s ability to form covalent bonds is important in
allowing for a wider variety of organic molecules. Living
things require such a variety to carry out life processes.
Four Classes of Organic
Compounds Found in Living
Things:
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1. Carbohydrates
2. Lipids
3. nucleic acids
4. proteins
Without these compounds cells could not function.
All of these compounds are long repeating units called
polymers.
 Polymers are large molecules formed when many
smaller molecules bond together usually in long chains.
 Each unit of a polymer is called a monomer (simple
molecule).
Polymer
Monomer
 1. Carbohydrates are organic compounds made
of carbon, hydrogen, and oxygen atoms in 1:2:1
ratio.
 All carbohydrates are made of carbon, hydrogen,
and oxygen.
 They are the main source of energy for living things,
and they are found in most foods—like fruits,
vegetables, and grains. Most energy that is used in
the human body is stored as carbohydrates.
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There are 3 types of
carbohydrates:
1. Monsaccharides or simple sugars. They are
the building blocks of carbohydrates.
 Examples of monosaccharides:
 1. Glucose is manufactured by plants during
photosynthesis. It is the main source of energy for
plants and animals.
 2. Fructose is found in fruits and is sweet. These
have the same molecular formulas, C6H12O6, but
different structural formulas, which make them
isomers.
Carbohydrates Cont.
2. Disaccharides are 2 monosaccharide
molecules linked.
 Example of a disaccharide is sucrose (table sugar),
which is composed of fructose and glucose.
Lactose that is found in milk is an example of a
disaccharide.
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Carbohydrates Cont.
 3. Polysaccharides are composed of many monosaccharide
subunits. Polysaccharides function as storehouses of the
energy contained sugars.
 Three examples of polysaccharides that store energy:
 1. Starch which is made by plants (like potatoes). Energy is passed
from potato to the person eating it primarily by the energy stored in
starch molecules.
 2. Glycogen which is made by animals. Both starch and glycogen are
made of hundreds of linked glucose molecules.
 3. Cellulose is a polysaccharide that provides structural support for
plants. Humans cannot digest cellulose (wood).
Starch
Glycogen in Liver Cells
Cellulose
 Lipids are non polar molecules that are not
soluble in water.
 Lipids are used to store energy (long term storage),
for insulation, and as protective coatings.
 Lipids are composed of 3 fatty acids bonded to a
glycerol molecule.
 Examples of lipids: fats, phospholipids, steroids,
including cholesterol, and waxes.
Fats
Cholesterol
Steroids
Waxes
Lipids Cont.
 The monomers of lipids are fatty acids
 Lipids are an important part of the structure and
functioning of cell membranes.
 Phospholipids make up the lipid bilayer of cell
membranes.
 Fats are lipids that store energy.
 Saturated Fats are solid at room temperature, and they
usually come from animals: butter
 Unsaturated Fats are liquid at room temperature, and
they usually com from plants like core peanut, and olive.
Phospholipid Bilayer
Lipids Cont.
 Waxes are highly waterproof.
 In plants, wax forms a protective coating on the
outer surfaces, for example on the leaves.
 In animals, wax forms protective layers, for
example ear wax.
3. Nucleic Acids are in all of your cells.
 The building blocks of nucleic acids are nucleotides.
 A nucleic acid is a long chain of smaller molecules
called nucleotides.
 A nucleotide has three parts;
 1. a sugar
 2. a base
 3. a phosphate group
Sugar
Phosphate Group
Base
 There are two types of nucleic acids:
1. DNA Deoxyribonucleic Acid
 DNA consists of 2 strands of nucleotides that spiral
around each other. DNA is a molecule shaped like a spiral
staircase also known as a double helix. The 2 strands of a
DNA molecule are held together by hydrogen bonds
between two bases across from one another. Your
chromosomes consist of very long strands of DNA, which
stores heredity information (or genetic code) that can be
use d to make proteins.
2. RNA Ribonucleic Acid
 RNA consists or a single strand of nucleotides
RNA
DNA
 4. Proteins are a chain of molecules called amino acids
linked together like parts on a necklace.
 Proteins are made of long chains of amino acids.
 Amino acids are the building blocks of proteins.
 There are 20 different amino acids, which bond to each
other by peptide bonds (covalent bonds formed between
amino acids).
 Some proteins called enzymes regulate chemical
reactions in the body but remain unchanged by the
reaction.
 The complete hydrolysis of a protein would result in the
formation of amino acids. Hydrolysis is a chemical
reaction in which water is used to break down a
compound.
Proteins Cont.
 ATP-Adenosine Triphosphate
 ATP carries energy in cells.
 ATP is a single nucleotide with 2 extra energy-
storing phosphate groups.
Energy and Chemical
reactions
 Energy is the ability to move or change
matter.
 A chemical reaction is a process during which
chemical bonds between atoms are broken
and new ones are formed, producing one or
more different substances.
 Reactants
Products
(starting materials) (forms) (newly formed substances)


Activation Energy the energy needed to start a chemical reaction.
Enzymes Help Biochemical reactions occur:
 Enzymes (proteins) are substances that increase the speed of chemical
reactions.
 Enzymes are proteins which are substances that reduce the activation
energy of a chemical reaction.
 A substance on which an enzyme acts during chemical reaction is called a
substrate.
 Each enzyme is specific and
only acts on a particular substance
called substrate. An enzyme has
deep folds on its surface, and these
fold form pockets called active sites.
Activation Energy= Energy needed to start a
reaction
 Factors that affect enzyme activity;
 1. Temperature
 2. pH
 3. Enzyme Concentration