1. Proteins are made up of the elements C,H,O, and N (but
in no set ratio).
2. Proteins are chains of Amino Acids (usually 75 or more)
that bond together via dehydration synthesis.
3. 40% of the average human body is made up of protein.
1. The building blocks of Proteins are amino acids.
2. There are three parts to an amino acids:
1. Amino Group (NH2 or NH3+) acts as a base (accepts
H+)
2. Carboxyl Group (COOH or COO-) acts as an acid
(donates H+)
3. R Group: there are 20
different possible R groups
Amino acids bond together via dehydration synthesis.
The amino acids bind together with
a peptide bond.
The PEPTIDE bond is formed
between C and N and one water is
lost (dehydration synthesis).
When the original two amino acids
form the beginning of the chain
(with one peptide bond) it is called a
DIPEPTIDE.
Then the chain grows to become a TRIPEPTIDE.
Ultimately you end up with a
POLYPEPTIDE (which can
have anywhere between 30
and 30,000 amino acids).
Another name for a
polypeptide is protein.
Every protein is different because the ORDER of amino acids is
different.
The chains come together differently due to the order of the
different R groups and how they bond together.
This structural difference also makes the polypeptides
(proteins) functionally different.
This is the first level of how
are formed.
proteins
It is simply the order of amino acids joined together with peptide
bonds.
It is the amino acid sequence that determines the nature and
chemistry of the protein.
If you change the order of amino acids, the protein may not be able
to do its job.
This is the second step in the
protein.
formation of a
When a peptide bond is formed, a double bonded oxygen is left over,
which is partially negative (the carboxyl group: COO-).
It is attracted to the positive NH3+ amino group from other amino acids
in the chain.
This attraction forms a HYDROGEN BOND.
This causes the chain to twist into either a spiral called an alpha helix
or a beta pleated sheet.
The next interactions take
between the R groups.
place
Some R groups are reactive and will interact with other reactive R
groups in the chain. These are the amino acids that are either charged
or that have a sulphur atom.
The interactions ( + and – attractions and S-S bridges) will fold the
molecule over into a highly specific 3-dimensional shape.
It is the 3-D shape that will determine the protein’s job or role in the
body.
The last level in protein formation is not seen in all proteins.
However, some proteins are actually 2 or more molecules joined to
form a functional protein. They are held together with an ionic
bond.
Two examples:
Insulin has 2 subunits
Hemoglobin has 4 subunits.
Peptide Bonds
Hydrogen Bonds
Interactions between R
groups
Ionic Bonds
The final shape of a protein (its tertiary or quaternary structure) is very
specific and enables it to do its job/function.
Any change in a proteins’ shape will affect its function.
Denaturation is when a protein's tertiary structure is lost.
This happens when the bonds
between the R groups are
broken.
When a protein is denatured,
the protein can’t do its job and
becomes useless.
How can this happen? There are three common ways:
1. Temperature:
High temperatures affect the weak Hydrogen bonds and
can distort or break them, thus changing the structural
shape.
A slight increase in temperature an
cause a reversible change (ie: fever).
A high temperature increase can
cause an irreversible change
(ie: cooking an egg).
How can this happen? There are three common ways:
2. Chemicals:
Heavy metals such as lead and mercury
are large atoms that are attracted the R
groups of amino acids.
They bond to the R group and distort
the protein’s shape.
This is usually irreversible (they usually
don’t want to ‘let go’).
How can this happen? There are three common ways:
3. pH:
As some of the R groups are acids and some are bases,
every protein (enzyme) has a preferred pH.
Any change in pH causes a change in
the acid-base R group interactions
and this will change the shape of the
protein.
1. Structural: proteins help make up all structures in living things
Actin & Myosin: muscle
proteins
Keratin: nails, hair,
horns, feathers
Collagen: bones, teeth, cartilage, tendon,
ligament, blood vessels, skin matrix
2. Functional: other proteins help us to keep our bodies
functioning properly and to digest our food.
Enzymes:
are proteins that are
catalysts which speed up reactions
and control all cell activities.
Hemoglobin
3. Food Source: once we have used up all of our carbohydrates
and fats, proteins will be used for energy.
Proteins are worth the least amount of
energy per gram.
Anorexia and Bolimia
Nucleic acids are acidic molecules that are found in the
nucleus of cells.
There are two types, both of which are very LARGE.
1. DNA: Deoxyribonucleic Acid
2. RNA: Ribonucleic Acid
All nucleic acids are composed of units called NUCLEOTIDES, which
are composed of three sub-molecules:
1. Pentose Sugar (ribose or deoxyribose)
2. Phosphate
3. Nitrogen Base (purine or pyrimidine)
They are formed by joining
their subunits together via
dehydration synthesis
(nucleotide + nucleotide …
= nucleic acid).
This is quite a complex
process to which we will
devote an entire unit to.
Adenine and Guanine
Have two rings
Found in both DNA and RNA
Memory Trick: It’s Got 2 Be GAP
Cytosine, Thymine, and
Uracil
Have only one ring
Cytosine is in both DNA and RNA
Thymine is in DNA only
Uracil
Uracil is in RNA only
Memory Trick: CUT the Pyramid
Structure of DNA:
DNA is composed of two complimentary
strands of nucleotides.
The two strands are joined by hydrogen
bonds which form between
complimentary nitrogen bases:
Adenine with Thymine (A-T or T-A)
They join with 2 hydrogen bonds
Cytosine with Guanine (C-G or G-C)
They join with 3 hydrogen bonds
When DNA is first made,
it is just two linear
strands of nucleotides
joined together.
Due to internal bonding,
the DNA molecule then
forms into a double helix
(twisted ladder).
a) Directs and controls all cell activities by
making all of the proteins and enzymes
b) Contains all of the genetic information
necessary to make one complete organism
of very exact specifications
RNA is made by DNA.
It is not confined to the nucleus, it moves out of
the nucleus into the cytoplasm of the cell.
It has Ribose sugar instead of Deoxyribose.
It has no thymines, and uses URACIL’s instead.
It is single stranded and therefore, no helix is
formed.
There are 3 types of RNA.
The function of RNA is to assist DNA in making proteins.
DNA
RNA
Nitrogen bases: A,T,G,C
Nitrogen bases: A, U, G, C
Sugar: deoxyribose
Sugar: ribose
Double stranded
Single stranded
1 type
3 types: a) mRNA – messenger
b) tRNA – transfer
c) rRNA – ribosomal
Found in the nucleus only
Found in the nucleus and the
cytoplasm
Forms a double helix
No helix
DNA makes DNA
DNA makes RNA
Very big molecule
Much smaller molecule
ATP is also thought of as a nucleic acid as it has the same
structure as a nucleotide. The only difference is that it has
THREE phosphate groups instead of one.
This is the energy source for the body.
Our mitochondria turn the energy of glucose into ATP.
Why is it a good molecule to store energy? It takes a lot of energy
to put two phosphate molecules together (both –’ve). So when
you break that bond, a lot of energy is released.
C6H12O6 + 6O2 -----> 6CO2 + 6H20 + energy (heat and ATP)