Biochemistry
Most of the human body is made up of water, H2O, with cells
consisting of 65-90% water by weight. Therefore, it isn't surprising
that most of a human body's mass is oxygen. Carbon, the basic unit
for organic molecules, comes in second. 99% of the mass of the
human body is made up of just six elements: oxygen, carbon,
hydrogen, nitrogen, calcium, and phosphorus.
Oxygen (65%)
Carbon (18%)
Hydrogen (10%)
Nitrogen (3%)
Calcium (1.5%)
Phosphorus (1.0%)
The Atom
The charge of a proton = +1 (positive 1)
Atomic Number
The charge of an electron = -1 (negative 1)
The charge of a neutron = 0 (neutral)
The mass of a proton = about 1 amu
The mass of a neutron = about 1 amu
The mass of an electron is close to zero in comparison to protons and neutrons
Protons and neutrons are found in the nucleus
Electrons are found in orbitals
Mass Number
The Atom
atomic number = The number of protons
The Atomic Mass = The mass of all protons, neutrons, and electrons.
Number of neutrons = The atomic mass rounded – The Atomic number
Or since the electrons weigh near zero
Number of Neutrons = Number of protons and neutrons – the number
of protons
The number of neutrons in Helium =
=2
4-2
Carbon
Draw an atom of Carbon. Identify the parts of the atom
-
-
6P
6N
-
-
Number of Protons 6
-
Number of Electrons 6
Number of Neutrons = 12 - 6 = 6
If there is no charge the number of protons = the number of electrons
What is the difference between an
atom and an ion?
An ion is a atom that has lost or
gained an electron.
Ions have a different number of
electrons than protons
An atom that looses a(n) electron(s)
becomes a positively charged ion
An atom that gains a(n) electron(s)
becomes a negatively charged ion
How are isotopes different?
How are isotopes different?
Isotopes have the same number of protons but different
numbers of neutrons
Elements, Molecules & Compounds
ELEMENTS:
Symbols can be one capital letter or a capital letter with a
lower case letter
For example:
C = carbon; Ca = Calcium
MOLECULES
The combination of 2 or more elements  H2; O2
COMPOUNDS:
A substance made of many different elements bonded
together
Example: H2O = ?
Made of 2 elements – hydrogen and oxygen
NOTE: the subscripts tell # of atoms of each element you have
Example Atoms: H, He, Li, Be, B, C, N, O, F, Ne
Example Molecules: O2 , H2O, CO2 NH3
How is an atom different than a molecule?
Example Atoms: H, He, Li, Be, B, C, N, O, F, Ne
Example Molecules: O2 , H2O, CO2 NH3
How is an atom different than a molecule?
Molecules are made up of more than one atom covalently
bonded
Example Elements: O2, H2, He, N2
Example Compounds: H2O, CO2 NH3
How is an element different than a compound?
Example Elements: O2, H2, He, N2
Example Compounds: H2O, CO2 NH3
How is an element different than a compound?
Elements have only one type of atom
Compounds have more than one type of atom (IONIC bond)
What atoms are present and how many are in each
compound?
O2 = Oxygen
H2O = Water
CO2 = Carbon dioxide
What atoms are present and how many are in each
compound?
O2 is Oxygen
2 Oxygen atoms
What atoms are present and how many are in each
compound?
H2O is Water
2 Hydrogen atoms
1 Oxygen atom
What atoms are present and how many are in each
compound?
CO2 = Carbon dioxide
1 Cabon atom
2 Oxygen atoms
Chemical bonds:
Forming a compound
Bond – to join together atoms
using electron energy/force
Atoms are most stable when their
outer e- cloud is full
Elements can share electrons to
fill their outer (valence) e- cloud
This causes stability
Ionic bonds
Forms through the electrical force between
oppositely charged ions
Opposites attract! ( + wants - )
One loses electron to the other, making one + and
one -
Covalent bonds
• Forms when atoms share a
pair of electrons
• Not all atoms easily gain or
lose electrons. Some
prefer sharing instead
• These bonds are generally
strong
• Almost all of the
substances that make up
organisms are molecules
held together by covalent
bonds
Figure 6.6
In covalent bonding the electrons are _shared__ between
the atoms. In Ionic bonding atoms are
____transferred____ from one atom to another.
Covalent bonding forms ____molecules______.
Ionic bonding forms __ions___.
What is polarity in a molecule?
Polarity is when there are charged sides in an overall neutral
molecule. Larger atoms tend to hog electrons and become
slightly negative
Oxygen is a neutral
molecule but the oxygen
side is slightly negative
and the hydrogen side
is slightly positive.
What is a hydrogen bond?
Hydrogen bonds in water
A hydrogen bond is a polar bond where hydrogen is involved.
There is an intermolecular attraction between positive and
negatively charged sides of different molecules
Properties of Water
If there are other beings who have seen Earth, he said, they
must surely call it “the blue planet.” The astronaut was
referring to the blue appearance of the water in the oceans,
which cover three fourths of Earth’s surface. Water is also the
single most abundant compound in most living things.
Things to know
Hydrogen bond – Because
of positive and negative
charges of water (polarity).
Water attracts other water
molecules.
Cohesion- attraction
between molecules of the
same substance.
Adhesion- attraction
between molecules of
different substances
Adhesion- Substance to
glass (capillary action)
7 properties of water
• Water:
• 1. is a powerful solvent – can dissolve things
• 2. is very cohesive (due to H bonds holding
water together)
• 3. has high surface tension
• 4. has high specific heat
• 5. has a high boiling point – a high heat of
vaporization
• 6. is a good evaporative coolant
• 7. has a high freezing point and lower density
as a solid than a liquid (density anomaly)
Water Properties
1. Powerful, versatile solvent – due to polarity
Water Properties
2. Very Cohesive behavior (due to H bonds holding
water together)
Water Properties
3. High Surface Tension
Water Properties
4. High Specific Heat
Water Properties
5. High Boiling Point – High Heat of
Vaporization
Water Properties
6. Good evaporative coolant
Water Properties
7. High freezing point and lower density as a solid than
a liquid (density anomaly)
Water is less dense in a frozen state
Water
This is unusual
for most
substances
Benzene
How is a solution different than a
suspension?
A solution is homogeneous meaning that the parts
dissolve and the mixture looks all the same
throughout
Mixtures
Solution
Solute- NaCl
Solvent- water
NaCl Dissolving in Water
When an ionic compound
such as sodium chloride is
placed in water, water
molecules surround and
separate the positive and
negative ions.
How is a solution different than a
suspension?
A suspension is heterogeneous meaning that the parts
do not dissolve and you can see different particles in
the mixture
What are the parts of a solution
What are the parts of a solution:
The solvent is the substance doing the dissolving
The solute is the substance being dissolved
Creamer- solute
Coffee- solvent
This is sugar water
What is the solvent here? ______water____________
What is the solute here?
_____sugar__________________
Macromolecules- giant molecules (make up living cells)
Made up of monomers
Monomers - smaller single units
Polymers – more than two monomers
put together
4 macromolecules in living things
Carbohydrates
Lipids
Proteins
Nucleic Acids
Compound
Monomer(s) – What
single units make
them up?
Function(s)
Examples
Carbohydrates
Monosaccharide
Main
source of
energy for
living
things
Monosaccharide
- glucose
DisaccharideSucrose (table
sugar)
Polysaccharidestarch,
cellulose,
chitin
Carbohydrates
Types of Carbohydrates
Sugar is sucrose which
is a disaccharide
Pasta is a starch which
is a polysaccharide
When diabetics test their
blood they test for glucose
which is a monosaccharide
Compound
Monomer(s) –
What single
units make
them up?
Lipids
Lipid
Used to
Saturated
molecules
store energy Fat- Butter
are made up
Unsaturated
of fatty acids
fat- oil
and glycerol
Function(s)
Examples
Saturated fat
Unsaturated fat
Compound
Monomer(s) Function(s)
– What
single units
make them
up?
Examples
Proteins
Amino Acid
Meat
Enzymes
Proteins are
used to form
bones and
muscles
Enzymes are
proteins that
regulate cell
processes
Proteins
Compound
Monomer(s) Function(s)
– What
single units
make them
up?
Nucleic Acids Nucleotide
Store or
transmit
genetic
information
Examples
DNA and
RNA
Contains C,H,O
Contains C,H,O
Contains C,H,O
Contains N
Contains N,P,S
Made of amino acids
Made of nucleotides
Subunits are monosaccharides
Fats and oils
Enzymes
DNA
RNA
Monosaccharides
Disaccharides
Polysaccharides
Sugars
Glucose
Starch
Cholesterol
Keratin
Hemoglobin
Actin
Myosin
Provides short-term energy
Provides long-term energy
Holds the genetic code
Catalyzes body reactions
Makes up the body
Makes up cell membranes
Body insulation
Double helix
Shaped like an E
What determines if a substance is
an acid or a base?
The concentration of H+ ions
(pH)
Acids have more H+ ions
(protons)
Example acids are: Lemon Juice,
Hydrochloric acid
Bases have more OH- ions
(hydroxide)
Example bases are: Bleach, Soap
7 is neutral
Acids and Bases
http://www.youtube.com/watch?feature=player_detailpage
&v=RF40cI2O16U
Carbon dioxide + Water  Carbonic Acid
What are the reactant(s) in the above reaction?
Carbon Dioxide + Water
What are the product(s) in the above reaction?
Carbonic Acid
Endergonic Reaction
Exergonic Reaction
What is activation energy? The energy required to start a
reaction
An exergonic reaction gives off energy
An endergonic reaction takes in energy
An enzyme is what kind of organic molecule? A
protein
An enzyme is a catalyst which means it speeds up a
reaction
An enzyme does this by lowering activation energy
(The energy needed to start a reaction.)
What are some roles of enzymes in living things?
To help with photosynthesis in plants and many
body processes