H
C
Ca
O
H
P
The Chemical Basis of Life
O
C
O
N
Na
O
Fe
Essential Questions:
1. What is the connection between chemistry
and biology?
2. What do you already know about this
question?
3. Are there some connections that come to
mind immediately?
We will be learning:
1. to appreciate the basic principles of chemistry which
are involved in life processess.
By:
1.1 being able to recognize that organisms are made of
atoms.
How would you organize the words below from
smallest to greatest?
Organisms
Elements
Atoms
Cells
Atoms
All living things are made up of atoms.
Atoms
Elements
Cells
Organisms
The smallest particles of matter, they cannot be broken down further by ordinary
means. They are made up of smaller subatomic particles called neutrons, protons,
and electrons.
Atoms
Structure
i) Nucleus: is the inner portion of the atom. It can contain both protons
and neutrons.
ii) Energy Levels (also called the orbitals or electron cloud): These levels
contain negatively charged particles called electrons.
Example:
Nucleus = central core
-very small & dense (little empty spaces)
-give an atoms its weight
-made up of:
1) Protons
2) Neutrons
Electron Cloud = surrounds the nucleus
-gives an atom its volume
-composed of electrons
-orbit the nucleus in energy levels (like a
magnet)
Definition of an Element
Elements are groups of the same type of atoms. The greatest portion of
living organisms are made up of 4 elements:
Carbon, Hydrogen, Oxygen and Nitrogen
C
H
N
O
If elements are made up of different atoms, how do we determine the specific structure of a
carbon atom? Or an oxygen atom? What tool do we have to help us?
The Periodic Table:
Atomic Number: the number of protons.
Neutrons: atomic number subtracted from the atomic mass.
Ion: An atom that has either lost or gained electrons.
Cation: Positively charged ion.
Anion: Negatively charged ion.
Isotope: Atoms of the same element having different atomic mass numbers.
Example:
Valence Electrons...
A biologists, we are not just interested in determining the number of protons, electrons,
and neutrons of specific atoms, but we are more interested in knowing how many
electrons atoms have in their outer orbital--the electrons known as valence electrons.
Why are we interested in these electrons?
How do we determine the number of valence electrons of each atom?
Valence Electrons...
We determine the number of valence electrons by numbering the vertical columns
of our periodic table from left-right (we skip the columns in the middle).
This number then corresponds to the number of valence electrons of each of the
elements in that column.
Example:
Li:
Mg:
Se:
Si:
Br:
Using this information, we can create a diagram of the number of valence electrons of
several different elements.
Lewis Dot Structures
draw the symbol
determine the number of valence electrons
place them around the symbol, start at the top and go around clockwise, each side
must have 1 dot before any of the four sides can be given a second dot.
Cl
Please use the information learned in today's class to draw a Lewis dot structure for
the first 18 elements.
When you're finished, predict which elements would be likes to "bond: with other
elements, based on the number of valence electrons each one has.
Review...
1. Draw a Lewis dot structure for He, Li, and F.
2. How many electrons does an element want to have in its outer shell? Why?
3. Based on the Lewis dot diagrams of He, Li, and F, what can we predict will
happen to their valence electrons?
We will be learning:
1. to appreciate the basic principles of chemistry which
are involved in life processes.
By:
1.2 realizing the relationship between the electron
structure of atoms and the type of bond which forms
Chemical Bonding
Atoms are most reactive when their outermost shell or energy level is incomplete.
2 types of Chemical Bonds:
i) Ionic Bonds:
deals with ions
Deals with the transfer of electrons between two atoms.
Example: "Sodium-Chloride"
ii) Covalent Bonds:
Are formed when atoms share an electron pair or pairs.
Diatomic molecules are held together by covalent bonds.
Examples: H2, Cl2, I2, Br2
Another compound held together by covalent bonds is water (H2O).
One line between elements symbols represents one pair of shared electrons (Cl
Cl)
Two lines represents two pairs of shared electrons (O
Three lines represent three pairs of shared electrons (C
O)
N)
Let's do a few more covalent bond diagrams:
1. I + I
2. C + H4
3. Br + Br
4. Se + O
In-Class Assignment:
1. Decide and write whether each pair will form an ionic
or a covalent bond.
2. Use arrows/lines to indicate what electrons will be
transferred or shared.
Pairs of elements:
1. Mg + S
2. Li2 + O
3. Li + Br
4. Na2 + S
5. Ca + F2
6. C + O2
7. S + O
8. H2 + O2
We will be learning:
1. to appreciate the basic principles of chemistry which are involved in life processes.
By:
1.3 understanding the relationship between chemical bonds and stored energy.
1.4 recognizing the importance and ongoing nature of various chemical reactions in the body.
1.5 discussing a chemical reaction-the reactants, products, and energy either required or
produced.
1.6 illustrate with examples the simlarities and differences between synthesis and decomposition
reactions.
1.7 describe some relationships which exist between synthesis and decomposition reactions in
relation to the functioning of the body.
Thought-Provoking Question:
When two elements combine, through a covalent or an ionic bond, what word can we
use to describe this process???
Chemical Reactions
A
+
B
AB
Reactants
Products
Synthesis Reaction
Synthesis is the combination of 2 or more substances to form a new compound. It is
when two or more elements or compounds unite to form one.
Examples:
2Na(s) + Cl2(aq)
2H2(g) + O2(g)
2NaCl
2H2O(g)
Decomposition Reaction
Opposite of synthesis. One substance breaks down (decomposes) to form 2 or more
simpler substances.
Example:
2H2O(g)
2H2(g) + O2(g)
So What?
How does everything we have learned connect to biology,
especially our human bodies?
Chemical or Bond Energy
In order for life processes to occur, energy is needed.
When chemical reactions occur in which bonds are broken, energy is released. When bonds
form energy is needed.
Green plants can transform light energy into potential bond energy of plant compounds
(glucose).
Heterotrophs, depend on the chemical compounds (glucose) produced in the bodies of green
plants or other organisms.
The energy in chemical compounds which animals take in, is actually in the bonds which
holds molecules together.
Bond energy is the energy in covalent and ionic bonds.
What are some other examples of synthesis and
decomposition reactions that occur in our body?
Review...
1. Why are synthesis and decomposition reactions said
to be opposite?
2. What is homeostasis?
We will be learning:
2. To investigate the properties of carbohydrates, lipids,
and proteins.
By...
2.1 explaining how carbon-based molecules interact with
each other through hydrogen bonding.
Polar Bonding
A special type of covalent bond where the sharing of
electrons is not equal
As a result of this unequal sharing, the molecule has
positive and negative ends
Example: Water (H2O)
+
H
O
+
H
H
+
-
+
-
O
H
+
+
H
H
HYDROGEN BONDING
Deals with polar molecules
Hydrogen bonds are formed between a hydrogen proton and the negative end
of another polar molecule.
In DNA the nitrogen base from one spine of the ladder are connected to the nitrogen
bases from the other spine of the ladder by means of hydrogen bonds.
Ex.
+
+
H
H
= hydrogen bond
_
O
O
_
H
+
H
H
+
O
_
H
+
+
Review...
1. What is polar and hydrogen bonding?
2. What is an example of a substance that displays
hydrogen bonds?
We will be learning:
2. to investigate the properties of carbohydrates, lipids, and proteins.
By:
2.1 explaining how carbon-based molecules interact with each other through hydrogen bonding.
2.2 comparing mono-, di-, and polysaccharides and then provide expamples of their usefulness to a living
system.
2.3 describing the relationship between fatty acids and fats by providing examples to illustrate when they are
useful to a living system.
2.4 describing the relationship between amino acids and proteins with reference to the peptide bond.
2.5 discussing enzymes using a series of key words which should be included in a concept web with the heading
of proteins.
2.6 indicating the component parts of a fat molecule.
2.7 recognizing the value of proteins by using examples from the body.
Organic Compounds
(Biological Molecules or Macromolecules)
Inorganic Chemistry:
Compounds that do not contain the element carbon (C).
Organic Chemistry:
Compounds that contain the element carbon (C).
Carbon can link with other carbon atoms or with other atoms to form chains which can be
long, branched, or in the form of rings.
Carbon forms for covalent bonds with other atoms.
Examples:
H
H
CH4
CO2
C
H
H
O
C
O
4 Groups of Organic Molecules
1. Carbohydrates
2. Lipids (fats and oils)
3. Proteins
4. Nucleic Acids
Organic Molecules
These organic molecules are absolutely essential to life as they provide us with energy
and as they fulfill various other needs...we will study carbohydrates first.
Carbohydrates
Made up of sugar units.
Composed of the 3 elements: C, H, and O, usually in a 1:2:1 ratio.
The bodies most important source of energy.
The human body can not produce carbohydrates on its own, the body must get
them from an external source (plants).
Carbohydrates are either single sugar units or polymers (long chains) of many
sugar units. Usually end in the suffix "ose".
There are 3 types of carbohydrates: Monosaccharides, Disaccharides, and
Polysaccharides.
1. Monosaccharides
Simplest of the sugars, they are made up of one sugar unit (Mono = 1).
They are found in the form of a ring.
Examples: glucose (found in human blood), fructose (plant sugar found in fruit) and
galactose (found in dairy products).
They all have the chemical formula of C6H12O6. They are isomers.
The structure of glucose is the following:
H
H
C
C
H
OH
OH
O
H
C
H
OH
H
C
C
H
OH
C
OH
2. Disaccharides
Formed by the combination of 2 monosaccharides (di = two).
All are formed by a chemical process called dehydration synthesis because water is removed
from the two monosaccharides.
Ex) glucose
+
glucose
C6H12O6
C6H12O6
maltose
+
water
C12H22O11
H2O
Sucrose (one glucose + one fructose), lactose(one glucose + 1 galactose), and maltose
(one glucose + one glucose) are examples.
Sucrose is white table sugar, extracted from sugar cane and beet.
Lactose is milk sugar.
Maltose is malt sugar found in seeds of germinating plants.
3. Polysaccharides
Formed by the union of many monosaccharides (poly = many).
Polysaccharides are very long chains.
Some examples are:
I) Starch: found in plant bodies and often stored in roots and seeds.
II) Cellulose: provides strength and support to plant body. Plant cell wall.
III) Glycogen: found in animal bodies. Animals can't make carbohydrates, but
they store them in the form of glycogen. It can be converted back to glucose.
Review:
1. What are the 3 elements that make up all
carbohydrates?
2. List and explain the usefulness of one carbohydrate.
We will be learning:
2. to investigate the properties of carbohydrates, lipids, and proteins.
By:
2.1 explaining how carbon-based molecules interact with each other through hydrogen bonding.
2.2 comparing mono-, di-, and polysaccharides and then provide expamples of their usefulness to a living system.
2.3 describing the relationship between fatty acids and fats by providing examples to illustrate when they are useful
to a living system.
2.4 describing the relationship between amino acids and proteins with reference to the peptide bond.
2.5 discussing enzymes using a series of key words which should be included in a concept web with the heading of
proteins.
2.6 indicating the component parts of a fat molecule.
2.7 recognizing the value of proteins by using examples from the body.
Lipids:
composed of C, H, and O; with a ratio of 1:2:1.
have more covalent bonds and therefore contain more
energy than carbohydrates.
most are non-polar molecules = do not dissolve in
water.
Lipids
What do Lipids do for the human body????
1) are a reserve supply of energy or fuel for the body.
2) take part in building certain cell parts (cell membrane).
3) help to form vitamins and hormones.
4) act as hormones themselves (steroids).
5) can be stored just under the skin to act like an insulating area.
3 main lipids: triglycerides, phospholipids, waxes
Most if not all have a 2 part structure; glycerol and fatty acids. They combine by
dehydration synthesis in different ratios.
Types of Lipids
Triglycerides
formed by the union of one glycerol and 3 fatty acids
triglycerides that are solid at room temperature are called fats and liquid at
room temperature are called oils.
a glycerol = chain of C and H with OH- groups; a fatty acid = chain of C and H
with -COOH (carboxyl) group
formed by dehydration synthesis
Triglycerides
Differ in the type of fatty acids they are made up of:
a) Saturated (animal fats)
all atoms are joined by single covalent bonds, therefore harder to break down
solid or semisolid at room temperature
bad fat
b) Unsaturated (plant fats)
contains at least 1 double bond, therefore easier to break down and
digest
oil or liquid at room temperature
Phospholipids
contains a phosphate molecule (PO4) attached to one GLYCEROL + 2 FATTY ACIDS (the
phosphate molecule replaces once of the fatty acids).
the phosphate molecule has a negative charge, giving it a polar end and making it
soluble in water.
one end is soluble in water (hydrophilic end; water loving) and one end that is insoluble
(hydrophobic end; water fearing).
phosopholipids are parts of cell membranes.
Waxes
long chain fatty acids + long chain alcohol or long chain fatty acids +
carbon rings.
insoluble in water.
make a waterproof coating for plant leaves or animal feathers/fur.
Review:
1. What is the main differences between triglycerides,
phospholipids, and waxes?
We will be learning:
2. to investigate the properties of carbohydrates, lipids, and proteins.
By:
2.1 explaining how carbon-based molecules interact with each other through hydrogen bonding.
2.2 comparing mono-, di-, and polysaccharides and then provide expamples of their usefulness to a living system.
2.3 describing the relationship between fatty acids and fats by providing examples to illustrate when they are useful
to a living system.
2.4 describing the relationship between amino acids and proteins with reference to the peptide bond.
2.5 discussing enzymes using a series of key words which should be included in a concept web with the heading of
proteins.
2.6 indicating the component parts of a fat molecule.
2.7 recognizing the value of proteins by using examples from the body.
Proteins
What Proteins Do:
1) Organelles in the cytoplasm of cells are made up of protein (mitochondria,
ribosomes).
2) Most parts of muscles, nerves, skin and hair are made up of protein.
3) Antibodies are specialized proteins that help the body defend itself against disease.
4) Enzymes are proteins that speed chemical reactions.
5) Proteins are essential for the building, repair, and maintenance of cell structure.
6) Proteins can supply energy for the tissues.
7) Proteins make up hormones which are used for body regulation (homeostasis).
8) Proteins form a large part of chromosomes.
Protein Structure:
-Proteins are made up of 20 different amino acids. The amino acids bond in a variety of
different orders, this gives a great variety of proteins.
-Each amino acid has 2 parts
an amino group
an acid group
H
N
H
O
C
C
Where dehydration
synthesis or bonding
with other molecules
occurs.
OH
H
Acid Group
Amino Group
Could be a variety of atoms,
it changes with the type of amino acid.
A bond forms between the nitrogen of the amino group of one amino acid and the carbon
of the acid group of the other amino acid. This is a peptide bond. Amino acids that make
up proteins are held together by peptide bonds.
H
N
H
H
O
C
C
H
Glycine
H
N
OH
+
H
H
H
O
C
C
N
OH
H
H
Alanine
Peptide Bond
-2 amino acids join to form a dipeptide, while 3 or more amino acids form a polypeptide. Most proteins
have 2 polypeptide chains.
-as there are 20 different amino acids, the possible combinations to form different proteins is almost
immeasurable.
Since proteins consist of amino acids, held together by peptide bonds, proteins are often
call polypeptides.
The human body can make many amino acids, but there are 8 the body can't make.
They are called essential amino acids, we must get them from our food. The lack of any
one of the 8 will lead to protein deficiency and disease.
Proteins have very complex patterns and bond arrangements - this makes them very
sensitive to changes in temperature, oxygen and pH level. These changes would cause
a protein to change shape or denature.
Review:
1. What makes proteins "polypeptides"?
2. What important functions do proteins carry out in our
bodies?
We will be learning:
2. to investigate the properties of carbohydrates, lipids, and proteins.
By:
2.1 explaining how carbon-based molecules interact with each other through hydrogen bonding.
2.2 comparing mono-, di-, and polysaccharides and then provide expamples of their usefulness to a living system.
2.3 describing the relationship between fatty acids and fats by providing examples to illustrate when they are useful
to a living system.
2.4 describing the relationship between amino acids and proteins with reference to the peptide bond.
2.5 discussing enzymes using a series of key words which should be included in a concept web with the heading of
proteins.
2.6 indicating the component parts of a fat molecule.
2.7 recognizing the value of proteins by using examples from the body.
Enzymes - A Type of Protein
Catalysts: are chemicals that speed up the rate of a chemical reaction, without altering the
products formed by the chemical reactions. Catalysts remain unchanged after the reaction.
Enzymes: are protein catalysts that speed up/or allow chemical reactions to occur in living
organisms. Enzymes allow low temperature reactions to occur in organisms, by reducing
the activation energy.
Every reaction (200,000 different reactions in the cell) uses a certain enzymes to catalyze it.
The molecules on which an enzyme works are called the substrate. Each substrate
molecule combines with a specific enzyme. They are sometimes called the enzyme substrate complex.
The active site of the enzyme is the area that joins with the substrate molecules. Each
enzyme has a specially shaped active site, so only specific substrate molecules can fit in.
Coenzymes help some enzymes bind to substrate molecules. They are organic molecules
made from vitamins.
Factors that effect enzyme activity:
1) Temperature: Proteins (enzymes) change shape when the temperature is too high or
low. This will cause a change in shape of the active site therefore the substrate and
enzyme do not fit together.
2) pH: A change in pH levels can alter the shape of an enzyme.
3) Concentration of Substrate Molecules: Increase the concentration of the substrate
molecules and you increase the number of collisions between the substrate and enzyme.
This will increase the rate of reaction.
4) Inhibitor Molecules: Inhibitor molecules have shapes very similar to the substrate
molecules. The inhibitors compete with the substrate molecules for the active site of the
enzyme.
We will be learning to:
3. describe the structures of nucleic acids.
By:
3.1 describing the similarities and differences in the structure of
DNA and RNA.
3.2 describing the process of replication and transcription.
Nucleic Acids
There are two types of nucleic acids:
1) DNA -- deoxyribonucleic acid
2) RNA -- ribonucleic acid
Structure of Nucleic Acids:
They are made up of repeating units of nucleotides.
All nucleotides are made up of 3 parts:
1) 5 carbon sugar
2) phosphate group
3) nitrogenous base: 5 types of nitrogen bases; adenine, guanine, thymine, cytosine and
uracil
i) DNA has the bases adenine, guanine, thymine and cytosine. In DNA adenine (A) always
bonds with thymine (T) and guanine (G) always bonds with cytosine (C).
ii) RNA has the bases adenine, guanine, uracil and cytosine. In RNA adenine (A) always
bonds with uracil (U) and guanine (G) always bonds with cytosine (C).
iii) Adenine and Guanine are called purines, they are in the category of nitrogenous bases
that are comprised of two rings bonded together.
iv) Cytosine, thymine uracil are called pyrimidines, they are in the category of nitrogenous
bases that are comprised of one ring.
DNA
The order of the nitrogen base in DNA determines the genetic code.
The arrangements of the DNA bases in the nucleus acts as patterns for the building and
functioning of all other cell parts.
Nucleotide Diagram
Phosphate Group
Nitrogenous Base
DNA is located in the nucleus. It has a shape of a double helix or a twisted ladder.
DNA Single Strand Diagram
DNA Double Strand Diagram
Review:
1. What is the structure of DNA?
2. What are two differences between DNA and RNA?
We will be learning to:
3. describe the structures of nucleic acids.
By:
3.1 describing the similarities and differences in the structure of
DNA and RNA.
3.2 describing the process of replication and transcription.
Replication of DNA
Replication: The process in which a single strand of nucleotides acts as a template for the
formation of a complementary strand. A single strand of DNA can make a complimentary
strand. DNA is capable of duplicating itself, this happens through a process called replication.
THE STEPS OF REPLICATION
(Remember DNA is a double helix. Both sides of the ladder are attached by nitrogen
bases)
1) The hydrogen bonds that hold the complementary nitrogen bases together are broken.
2) The two edges of the ladder unzip, leaving 2 single parent strands.
3) The 2 parent strands act as a template or a mold. Free-floating nucleotides in the cell
attach to the parent strands. The free floating nucleotides attach themselves at their matching
bases (A-T, C-G)
4) Enzymes called polymerazes then come fuse the free floating nucleotides to the parent
strand. The result is 2 complimentary strands of DNA. The 2 new strands of DNA are identical
to the parent strand.
5) Sometimes mistakes can happen when the bases match up. There are special enzymes
that act as proof-readers and they run the strands of DNA to look for mistakes. Once a
mismatch is noted, another enzyme comes in, snips the error out and the right nucleotide is
added.
RNA
RNA is a single stranded nucleic acid used to translate the information of DNA into
protein structure.
It acts as a messenger by taking the instructions of the DNA out of the nucleus and into
other parts of the cell.
There are two types of RNA:
1) mRNA: reads the code from the DNA molecule and is called the
messenger RNA.
2) tRNA: called the transfer RNA, picks up codes from the amino acids
circulating in the cytoplasm and shuttles them to the mRNA to be used in the
translation process in the making of proteins.
Protein Synthesis:
Transcription/Translation
Transcription: the process by which the genetic code is transferred from the DNA molecule to
the mRNA molecule. Transcription is also known as protein synthesis or the making of
proteins.
Things to Remember:
Proteins are made from amino acids.
DNA is involved in transcription and it never leaves the nucleus.
RNA and DNA have very similar structures.
mRNA reads the DNA code in the nucleus and carries it to the ribosomes where the making
of proteins will be completed in a process called translation.
Steps to TRANSCRIPTION
1. The double stranded DNA molecule in the nucleus unzips.
2. Once the DNA molecule unzips, nucleotides from the mRNA match up with the appropriate
base on the DNA. The single DNA strand is acting as a blue print.
DNA RNA
C
G
A U
3. The mRNA nucleotides, that have attached to the single strand of DNA, join into a long
chain.
4. The mRNA strand moves away from the parent DNA strand.
5. The two strands of original DNA then rejoin.
6. The process of transcription has been completed. The single stranded mRNA molecule
moves out of the nucleus through the nuclear membrane and carries the nitrogen-base code
to the ribosomes in the cytoplasm. This happens in a process called translation.