Chemistry of Life

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Transcript Chemistry of Life

Chemistry of
Life
I. Nature of Matter
Chemistry will help you learn about
biology because you’re a chemical
machine.
A. Atoms
 All
matter consists of atoms.
 An atom is the smallest unit
of matter that cannot be
broken down.
A. Atoms
Draw an atom including the electron cloud.
A. Atoms
3 Types of particles make up an atom:
 Electrons
Negatively charged (-)
 Protons
Positively charged (+)
 Neutrons
No charge
A. Atoms
Electrons form the electron cloud which
has a negative charge
 Atoms typically have one electron for
each proton

Example: 3 electrons (-), 3 protons (+)
= no charge (neutral)
B. Elements
100 known elements
 Elements differ in the number of protons
they have
Ex. Hydrogen has 1 proton & 1 electron
Oxygen has 8 protons & 8 electrons
 Neutrons are sometimes equal to the number
of protons

B. Elements
Isotopes- atoms of an element that contain
different numbers of neutrons
Example-Carbon-12, Carbon-13, Carbon-14
Carbon-12 has 6 protons and 6 neutrons
Carbon-13 has 6 protons and 7 neutrons
Carbon-14 has 6 protons and 8 neutrons
C. Chemical Bonding -a force that
joins atoms of 2 or more different elements
Compound-made of the joined atoms
of 2 or more different elements.
Ex. Na (sodium) + Cl (chloride) 
NaCl (table salt)
1. Covalent Bonds


Form when 2 or more
atoms share electrons
to form a molecule.
Examples of covalent
bonds: CO2 , H2O
1. Covalent Bonds
Electron arrangement:
Hydrogen and Helium
hold up to 2 electrons in
the outer level; all other
atoms can hold up to 8
electrons in the outer level
Outer level electrons are
called “valence electrons”.
2. Hydrogen Bonds in H2O

The water molecules
have a partial positive
and negative end. This
is called POLAR.

Polar molecules have an
uneven distribution of
charge
3. Ionic Bonds
Form IONS
Ions-Atom or molecule that loses or gains an
electron; they have an electrical charge because of
unequal # of protons and electrons
 Ions of opposite charge may interact to form an
ionic bond
Example (text pg. 40): Draw an ionic bond in Na Cl

Na
Cl

NaCl
II.
Water and Solutions
A. Water in Living Things
 70%
of the
human body is
water
 Cells are filled
with water and
are surrounded
by water.
A. Water in Living Things
Properties of Water
1. Storage of heat:
Water heats slowly and
retains heat longer than
many other substances.
Example: Some organisms
release excess heat by
sweating (cool off)
Feet have more sweat
glands than any other
part of the body
(250,000) and can
produce up to a pint
of perspiration each
day.
A. Water in Living Things
Properties of Water
2. Cohesion: attraction between
substances of the same kind
 Cohesion is caused by the
hydrogen bonds between water
molecules
 Surface Tension: caused by the
attraction of water molecules
http://www.youtube.com/watch?v=45yabrnryXk
A. Water in Living Things
Properties of Water
3. Adhesion: attraction between different
substances
 Adhesion powers capillary action in
which water molecules move water through
a narrow tube such as a stem of a plant

The attraction of the water to the walls of
the tube sucks the water up more strongly
than gravity pulls it down.
A. Water in Living Things
Adhesion
Water moves up a
plant through a
combination of
capillary action,
cohesion, and
other factors
B. Aqueous Solutions
What is a solution?
A mixture in which one or more
substances are evenly distributed in
another substance.
Importance of solutions in the body
Certain substances that dissolve in
water can move within and between
cells (e.g. sugar)
1. Polarity of Solutions

Ionic compounds
and polar molecules
dissolve best in water.
Nonpolar molecules
DO NOT.

Cell membranes
depend on the
interaction of polar
and nonpolar
molecules.
2. Acids and Bases
 When
hydrogen bonds in H2O break,
a hydrogen (H+) ion and a hydroxide
ion (OH-) forms
Draw this:
H2O  H+
+ OH-
2. Acids and Bases
Water has an equal # of H+ and OH- ions
Acids-have a high concentration of H+ ions
Bases-have a lower concentration of H+ ions and
forms OH- ions
pH scale-measures the concentration of H+ ions
in a solution
2. Acids and Bases
Draw the pH scale
III. Chemistry of Cell
Macromolecules “Building Blocks”
a.
Organic compounds contain Carbon atoms that are
covalently bonded to other elements.
a.
4 classes of organic compounds found in living
things:
1. carbohydrates
3. protein
2. lipids
4. nucleic acid
Carbohydrates
-are made up of carbon,
hydrogen, and oxygen
atoms in 1:2:1 ratio
 -are a key source of
energy
 -are found in most
foods, especially fruits,
vegetables, and grains
Monosaccharides
Monosaccharides -single sugars
 Examples: glucose, fructose
 Function: as a major source of energy in
cells

Disaccharides
Disaccharides-double sugars (2
monosaccharides)
 Examples: sucrose (made of glucose and
fructose)

Polysaccharides
Polysaccharides-3 or more
monosaccharides
 Examples: starch
 Function: storehouses of
the energy stored in sugar
 Starch-Stored by plants
 Glycogen-made and stored
by animals

Lipids
Lipids are nonpolar and are
NOT soluble in water
 Lipids include: fats,
phospholipids, steroids,
and waxes
 Fats-Store energy
 Phospholipids-Form cell
membranes

Lipids
*** Examine the difference between saturated and
unsaturated fatty acids.
* Saturated fats
are solid at room
temperature
* Unsaturated fats
are liquid at room
temperature
Proteins
 Large
molecules formed by amino
acids
 AMINO ACIDS ARE THE
BUILDING BLOCKS OF
PROTEIN.
Proteins tend to fold into compact
shapes
Functions of Proteins





Some proteins are enzymes and promote chemical
reactions.
Collagen is a protein found in skin, ligaments,
tendons, and bones.
Antibodies defend against infection.
Aid in muscle contraction
Hemoglobin is a protein found in blood that carries
oxygen from the lungs to body tissues.
Nucleic Acids
 Found
in ALL cells
 It is a long chain of
smaller molecules called
nucleotides
(A, T, G, and C)
 2 types of Nucleic acids
Nucleic Acids
1.
2.
DNA-deoxyribonucleic acid: made of 2 strands;
stores hereditary information
RNA-ribonucleic acid; made of 1 strand ;
manufactures proteins
Nucleic Acids
ENERGY
MOLECULE IS
ATP.
ATP is adenosine
triphosphate;
temporarily
stores energy
IV. Energy and Chemical Reactions

A. What is energy?
Ability to move or change matter

Forms of energy include:
light
heat
chemical
mechanical
electrical
IV. Energy and Chemical Reactions
A. What is energy?
In chemical reactions energy is stored
or released.
Reactants  Products
NaCl
 Na+ + Cl-
B. Activation Energy
Activation Energy-energy needed
to start a chemical reaction
It is a “push” that starts a
chemical reaction
C. Enzymes
Enzymes-increase the speed of chemical reactions
 Most enzymes are proteins.
 Decrease the amount of energy needed to start a
chemical reaction
C. Enzymes



Allow organisms to maintain homeostasis
Example: Carbonic anhydrase allows your body
to eliminate CO2 efficiently
Draw the reaction
Carbonic anhydrase
CO2 + H2O
H2 CO3
C. Enzymes
 Enzyme
specificity-Enzymes act on
only certain substances during a
chemical reaction
 These substances are called substrates
C. Enzymes
Label active site, substrate, and enzyme
C. Enzymes
What can effect enzyme
activity?
pH or temperature
Name of Made up
substance of ?
Major functions
Examples
of
Carbohydrates Carbon
Hydrogen
Oxygen
Key source of energy
found in most food
Fruits, vegetables
grains
Lipids
Hydrogen
Carbon
Oxygen
Important part of the
structure and functioning
of the cell membrane
Fats,
phospholipids
steroids, waxes
Nucleic Acid
Sugar phosphate
nitrogen base
Stores heredity
DNA
information manufacture
RNA
of proteins; promoting
chemical reactions to form
proteins
Proteins
Amino Acids
Promote chemical
reactions; defend against
infection
Eggs, Milk, fish
Poultry, meat
legumes