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Chemistry of Life
Chapter 2
Atoms
The word atoms is gotten from the word
atomos which means “unable to cut”
All atoms are made up of three particles:
Protons, Neutrons, and Electrons.
Protons and Neutrons are in the nucleus of
an atom.
Electrons circle around the nucleus
Atomic Structure
Protons have a positive charge.
Neutrons have no Charge.
Electrons have a negative charge.
The atomic number on a periodic table
tells you the number of protons an
element has.
Atoms
Elements
Atoms make up elements.
Elements are identified by a 1 or 2 letter
abbreviation.
Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
Calcium (Ca)
Gold (Au)
The first 4, C,H,O,&N make up over 96% of
the human body
An Element in the Periodic Table
Section 2-1
6
C
Carbon
12.011
Isotopes
Not every atom is the same.
Sometimes atoms have different
numbers of neutrons.
This causes them to have different
atomic masses.
As a result some atoms are unstable
and are called radioactive.
Figure 2-2 Isotopes of Carbon
Section 2-1
Nonradioactive carbon-12
Nonradioactive carbon-13
6 electrons
6 protons
6 neutrons
6 electrons
6 protons
7 neutrons
Radioactive carbon-14
6 electrons
6 protons
8 neutrons
Isotopes
Radioactive isotopes have a variety of
uses.
Labels/Tracers
Cancer Treatment
Dating fossils.
Compounds
Atoms can combine to form
compounds.
A compound is very different from an
element.
I.e. NaCl
Compounds can form either by Covalent
or Ionic bonding.
Figure 2-3 Ionic Bonding
Section 2-1
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na+)
Chloride ion (Cl-)
Transfer
of electron
Protons +11
Electrons -11
Charge
0
Protons +17
Electrons -17
Charge
0
Protons +11
Electrons -10
Charge
+1
Protons +17
Electrons -18
Charge
-1
Figure 2-3 Ionic Bonding
Section 2-1
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na+)
Chloride ion (Cl-)
Transfer
of electron
Protons +11
Electrons -11
Charge
0
Protons +17
Electrons -17
Charge
0
Protons +11
Electrons -10
Charge
+1
Protons +17
Electrons -18
Charge
-1
Water and Diffusion
Water is the universal solvent and makes up
70% to 95% of all organism’s body mass.
Polar molecule- a molecule with an unequal
distribution of charge.
Because electrons spend more time near one
atom than another in a polar molecule, the
molecule will have a positive side and a
negative side. Like a magnet.
Polarity
Molecules that exhibit polarity attract many ionic
compounds like salts & as well as other polar
molecules like sugars.
Polarity is responsible for making water the
universal solvent
Properties of Water
Hydrogen bonds- a weak attraction that
bonds polar molecules to each other.
H bonds give water surface tension and the
property of capillary action.
Water resists temperature change acting as
an insulator for cellular activity.
Water expands when it freezes, making ice
less dense than liquid water. That’s why it
floats.
Mixtures
Water is not always pure.
It can form :
Solutions
Suspensions
Figure 2-9 NaCI Solution
Section 2-2
ClCl-
Na+
Na+
Water
Water
Figure 2-9 NaCI Solution
Section 2-2
ClCl-
Na+
Na+
Water
Water
Acids & Bases
pH measures of how acidic or basic a
solution is.
There are three solutions
An acid
A Base
A neutral solution
Examples of Acids and Bases
The pH scale runs from 0 to 14.
0- 6.99 is acidic.
7 -7.99 is neutral
8 -14 is basic,
pH Scale
Section 2-2
Increasingly Basic
Oven cleaner
Increasingly Acidic
Neutral
Bleach
Ammonia solution
Soap
Sea water
Human blood
Pure water
Milk
Normal
rainfall
Acid rain
Tomato
juice
Lemon juice
Stomach acid
Life Substances
Carbon is the basic
element for almost
all living things.
Carbon has 4 electrons
in its outer energy
level and forms
covalent bonds in
three different ways.
Carbon as a Base
Carbon atoms bond in either straight
chains, branched chains, or rings.
Isomer- molecules w/ the same formula
but different configuration.
Glucose (C6H12O6) and fructose (C6H12O6)
are isomers.
Polymer- a large molecule made of a long
chain of molecules. (proteins)
Figure 2-11 Carbon Compounds
Section 2-3
Methane
Acetylene
Butadiene
Benzene
Isooctane
Making Polymers
Condensation reaction- forms polymers. Small
molecules that have an H+ and an OH- that
can be removed forming a covalent bond
between and releasing water as a byproduct.
Breaking Polymers
Hydrolysis reaction- breaks polymers. Water
dissolves polymers by attaching an H+ and OHion to the subunits of a polymer.
Which reaction is responsible for a delicious glass
of kool-aid? Hydrolysis or condensation?
Organic Compounds
There are 4 principle types of organic
compounds that make up living things:
Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
They are used to make tissue
They are used to store and produce energy.
Consists of carbon, hydrogen, & oxygen.
Figure 2-13 A Starch
Section 2-3
Starch
Glucose
Carbohydrates
There are three subunits of carbohydrates.
Monosaccharide- a simple carbohydrate, isomers
glucose & fructose.
Disaccharide- two monosaccharides linked
together, a polymer of glucose & fructose make
sucrose
Polysaccharide- the largest carbohydrate polymer
made of many monosaccharide subunits. Starch,
glycogen, & cellulose are polysaccharides that
store energy for organisms.
Lipids
These are your fats and oils
They are composed of carbon, hydrogen, &
oxygen with a much greater proportion of H
& C than O.
C57H110O60
Fats are insoluble in water because they are
non-polar.
Lipids are used for cell membranes and energy
storage.
Nucleic Acids
These are organic molecules that store genetic
information, or the blueprints for life.
The smallest unit of a nucleic acid is called a
Nucleotides
Nucleotides have consisting of a nitrogen base,
a sugar, and a phosphate.
I.e. Deoxyribonucleic acid and ribonucleic acid:
DNA & RNA
Proteins
These are large polymers consisting of
carbon, hydrogen, oxygen, nitrogen, &
sulfur.
Provide structure for tissues and are
important for metabolism.
Proteins continued…
An amino acid is the basic unit of a protein.
All amino acids are a carbon atom with an amino
group (NH2), a carboxyl group (COOH), a
Hydrogen atom (H), and a variable group.
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
Alanine
Serine
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
Alanine
Serine
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
Alanine
Serine
Figure 2-17 A Protein
Section 2-3
Proteins also regulate
oxygen in the blood,
contract muscles,
control chemical
rxn’s, and support
the immune system.
Protein activities
Proteins, complex chains of any
combination of the 20 amino acids
provide the material for fingernails,
hair, horns, & hoofs.
Enzymes
A special class of proteins that are vital
to an organism’s survival.
They work by lowering the energy it
takes to start a chemical reaction.
Effect of Enzymes
Section 2-4
Reaction pathway
without enzyme
Activation energy
without enzyme
Reactants
Reaction pathway
with enzyme
Activation
energy
with enzyme
Products
Figure 2-19 Chemical Reactions
Section 2-4
Energy-Absorbing Reaction
Energy-Releasing Reaction
Activation
energy
Products
Activation energy
Reactants
Reactants
Products
Figure 2-19 Chemical Reactions
Section 2-4
Energy-Absorbing Reaction
Energy-Releasing Reaction
Activation
energy
Products
Activation energy
Reactants
Reactants
Products
Enzyme Theories
Lock and Key Model
Enzyme fits specifically to its substrate.
Induced Fit Model
Active site on the enzyme changes shape
slightly to “fit” its substrate.
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Substrates
bind to
enzyme
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Substrates
bind to
enzyme
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Substrates
bind to
enzyme
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Substrates
bind to
enzyme
Concept Map
Section 2-3
Carbon
Compounds
include
Carbohydrates
Lipids
Nucleic acids
Proteins
that consist of
that consist of
that consist of
that consist of
Sugars and
starches
Fats and oils
DNA and RNA
Enzymes
and others
which contain
which contain
which contain
which contain
Carbon,hydrogen,
oxygen, nitrogen,
phosphorus
Carbon,
hydrogen,oxygen,
nitrogen,
Carbon,
hydrogen,
oxygen
Carbon,
hydrogen,
oxygen
Chemical Reactions
Chemical reactions occur when bonds
between molecules are broken or
formed.
Example: Mg+2HCL
MgCL2+H2
Note the same # of atoms on each side
of the reaction equation. This is
referred to as balance.
Balancing Equations
Example: 2C2H2+5O2
Try this one: 2H2S+3O2
2H2O+4CO2
_H2O+_SO2
Now this one: 6H2O+6C
C_H_O_
Metabolism- all of the chemical reactions
that occur inside organisms.