Download Fatty Acids: The lipid building blocks: The common building block for

There are three different functions for lipids in our bodies:
Energy storage
Forming the membranes around our cells.
Hormones and vitamins
Fatty Acids: The lipid building blocks: The
common building block for most of the
different types of lipids is the fatty acid.
Fatty acids are composed of a chain of
methylene groups with a Carboxyl
functional group at one end.
Saturated and unsaturated FAs form different
types of lipids.
The methyl chain is the fatty part, the Carboxyl, the acid. The fatty acid chains are
usually between 10 and 20 Carbon atoms long. The fatty "tail" is non-polar
(Hydrophobic) while the Carboxyl "head" is a little polar (Hydrophillic).
Fatty acids can be saturated (meaning they have as many hydrogens bonded to their
carbons as possible) or unsaturated (with one or more double bonds connecting their
carbons, hence fewer hydrogens). A fat is a solid at room temperature, while an oil is a
liquid under the same conditions. The fatty acids in oils are mostly unsaturated, while
those in fats are mostly saturated.
Proteins
The biological macromolecules are all polymers. Carbohydrates are sugar polymers.
We built lipids from fatty acids, phosphate groups, and glycerol. Now we come to
proteins, which are also polymeric. The subunits which make-up Proteins are Amino
Acids. The amino acids are joined together by dehydration synthesis to form chains,
which are hundreds of amino acids long; called proteins. Proteins function as enzymes
or as structural units in cells. They do most of the "work" in a cell. Almost all of the
exciting stuff; metabolism, memory, hormone action, and movement involves proteins.
Amino acids are aptly named. See which functional
groups you recognize as part of this amino acid.
You will also notice there is an R as part of this
molecule. There is no element with the abbreviation,
R. This letter is used as a sort of chemical variable,
like X in math. At this position (the R-group) in an
amino acid, different functional groups can be
present. There are twenty different types of amino
acids found in proteins. Each has a different R-group.
There are twenty different types of amino acids found in proteins: The eight
essential amino acids are shown in bold. Essential amino acids must be acquired in the
diet; nonessential amino acids can be synthesized by the body. Complete dietary
proteins contain both the essential and nonessential amino acids. Incomplete proteins
are missing one or more amino acids. Proteins are digested and degraded by enzymes
in the stomach and further digestion occurs in the small intestine. This process takes
the proteins you consume and coverts them into the component amino acids by
breaking the covalent bonds which connect the subunits of the proteins.
alanine
arginine
asparagine
aspartic acid
cysteine
glutamic acid
glutamine
glycine
histidine
isoleucine
leucine
lysine
methionine
phenyalanine
proline
serine
The 20 types of amino acids differ only at the R position.
threonine
tryptophan
tyrosine
valine
DNA is composed of two chains of nucleotides twisted around each other to
form a double helix.
Each of the nucleotides that compose DNA consist of three components (sort of like
functional groups). These components are: A Phosphate Group, A Deoxyribose Sugar, and
a Nitrogen containing Base.
The structure of the bases is all that differentiates one nucleotide from another. Each of the four
Nucleotides contains a different base, A,T,C ,or G. Right,a GC base pair with three hydrogen
bonds. Left, an AT base pair with two hydrogen bonds. Non-covalent hydrogen bonds between
the pairs are shown as dashed lines.
A carbohydrate is an organic compound
that is composed of atoms of carbon, hydrogen
and oxygen in a ratio of 1 carbon atom, 2
hydrogen atoms, and 1 oxygen atom. Some
carbohydrates are relatively small molecules, the
most important to us is glucose which has 6
carbon atoms. These simple sugars are called
monosaccharides.
Hooking two monosaccharides together forms a more
complex sugar, such as the union of glucose and fructose to
give sucrose, or common table sugar. Compounds such as
sucrose are called Disaccharides (two sugars). Both
monosaccharides and disaccharides are soluble in water.
Sugars are most often found in the form of a "RING". The
glucose molecule in the image above and the one in the image
below (Glc) are really the same molecule, just arranged
differently.
The image on the left shows two monosaccharides,
Glucose and Galactose (Gal). Examine their structure and
you will notice there is very little difference. Their molecular formulas, C6H1206, are even
the same. Molecules with the same chemical formula, but different molecular
structures are called Isomers.
Larger, more complex carbohydrates are formed by linking shorter units together to
form long or very long sugar chains called Polysaccharides. Because of their size,
these are often times not soluble in water. Many biologically important compounds such
as starches and cellulose are Polysaccharides. Starches are used by plants, and
glycogen by animals, to store energy in their numerous carbon-hydrogen bonds, while
cellulose is an important compound that adds strength and stiffness to a plant's cell wall.