LIPIDS AND PROTEINS
AND NUCLEIC ACIDS
October 15, 2014
Lipids are made up of the elements C,H,O but in no set
ratio.
Lipids are large molecules that are insoluble in water.
1. Composed of 3 fatty acids
bonded to 1 glycerol.
2. Fatty acids contain a long
chain of 16-18 Carbons
with an acid end.
3. Glycerol is a small 3
Carbon chain with 3
alcohol (OH) groups
4. These two molecules bind
together via dehydration
synthesis
1. Saturated fats:
There are no double bonds in the carbon chains of the
fatty acids.
The carbons are filled with hydrogens.
Unhealthy.
They mostly come from animals.
Become solid at room temperature.
Examples: lard, butter, animal fats…
2. Unsaturated fats:
There are one (monounsaturated) or more
double bonds (polyunsaturated).
Mostly come from plants.
They are liquid at room temperature.
Healthy
Examples: olive oil, corn oil, palm oil…
Are used to make up the two
layered cell membrane of all
cells.
In phospholipids, the third fatty
acid group of a triglyceride is
replaced by an inorganic
phosphate group (PO43-).
This creates a polar end:
The phosphate end is water soluble
(hydrophilic)
The fatty acid is not water soluble
(hydrophobic)
hydrophilic
hydrophobic
Steroids structurally look very different
from lipids, but are also water
insoluble.
They are made up of 4 Carbon ring
molecules fused together.
Examples: testosterone, estrogen,
cholesterol, and vitamin D.
Used as sex hormones
1. Long term storage for energy (more efficient
spacewise than glycogen or starch).
2. Insulation and protection in animals
3. Making some hormones (steroids)
4. Structure of cell membranes.
Without lipids, we would have no cells.
• Found in fish and leafy vegetables
• Other foods are now offering omega-3’s (eggs, cereals, margarine…)
• Help to reduce cancer
• Helps with vision
• Helps us think better
Scientific evidence has
shown that dietary
saturated and trans fats
can increase your risk of
developing heart disease.
TIME TO DRAW
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 from 30 and
30,000 amino
acids…sometimes
more).
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
proteins are formed.
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
formation of a protein.
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
place between the R groups.
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 Bulimia
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 submolecules:
1. Pentose Sugar (ribose or deoxyribose)
2. Phosphate
3. Nitrogen Base (purine or pyrimidine)
They are formed by
joining their subunits
together via
dehyd/condensation
synthesis (nucleotide +
nucleotide … =
nucleic acid).
This is quite a complex
process to which we
will learn this year.
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
Uracil
Thymine is in DNA only
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. (ladder
configuration)
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.
The
function
of RNA
to assist DNA in making proteins.
There
are 3 types
of isRNA.
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)