Organic Compounds
Carbohydrates
• The carbohydrates, or Hydrates of Carbon, are
organic molecules constituted by atoms of Carbon,
Oxygen and Hydrogen. Carbohydrates also are
called Saccharides, Glycids, or Sugars.
• The basic formula for carbohydrates is CH2O. We
can distinguish three kinds of carbohydrates:
Monosaccharides (one saccharide), Disaccharides
(two molecules of saccharide) and polysaccharides
(three or more molecules of saccharides).
Carbohydrates
• General Functions
– Store Energy
– Structural purposes
• Example
– Cellulose, starch, sugars
Monosaccharides
• Monosaccharides such as glucose are
carbohydrates that cannot be hydrolized to
obtain smaller molecules of carbohydrate.
• The condensed formula of Glucose is:
– C6H12O6
Monosaccharides
• The structural formula and
spacefilling model presented here
represent glucose.
• Glucose is an example of a
monosaccharide, a carbohydrate that
cannot be broken into simpler
carbohydrates.
Monosaccharide
Monosaccharides can join
to form disaccharides
• The structural formulas show that pairs
of monosaccharides can join together
through a glycoside linkage to form a
disaccharide.
• A disaccharide is a carbohydrate that
can be broken into two simpler
carbohydrates.
Digestion converts
disaccharides into
monosaccharides
• An important function of digestion is to
break the glycoside linkage in
disaccharides, converting them to
monosaccharides that can be used for
energy storage.
Polysaccharide
• Starch is an example of a
polysaccharide
• Many monosaccharides can form
glycoside linkages to build what
amounts to a sugar polymer: a
polysaccharide.
• Starch is one example that consists of
repeating glucose units.
Cellulose
• Cellulose is the most abundant organic
material. Cellulose is synthesized by plants
as a structural material to support the weight
of the plant.
Digestion converts
polysaccharides into
monosaccharides
• An important function of digestion is to
break the glycoside linkages in
disaccharides, converting them to
monosaccharides that can be used for
energy storage.
• As an example, the polysaccharide
starch is broken into glucose molecules
during digestion
Lipids
• General Functions:
– Store energy
– Important part of membranes
• Example:
– Fats, oils, waxes
– Cholesterol, corn oil
General structure of fatty
acids: a type of lipid
• Fatty acids are carboxylic acids with a
long hydrocarbon tail. In the general
structure, "R" represents the large
hydrocarbon tail.
• R generally represents a hydrocarbon
chain of 3 to 19 C atoms.
Oleic acid, a fatty acid
• Oleic acid is in olive oil, peanut oil, and
human fat. It is an unsaturated fatty acid: the
hydrocarbon tail has a double bond. Since
there is only one double bond, the fatty acid
is monounsaturated.
General formulas show how
glycerol and fatty acids
form triglycerides
• The -OH groups on glycerol can react
with the -COOH groups on fatty acids,
causing the fatty acid to join to the
glycerol, and releasing water.
• The glycerol and fatty acids react to
form triglycerides.
Triglycerides are broken
down by digestion
• Digestion breaks down triglycerides into
glycerol, monoglycerides, diglycerol,
and fatty acids. These products pass
through the intestine walls, where they
reassemble into triglycerides as they
pass into the blood.
• Digestion of triglycerides is slower than
digestion of other food types.
Phospholipids are like a
triglyceride in which
phosphate has replaced a
fatty acid
• The phosphate group makes the
phospholipid polar.
• Phospholipids are found in cell
membranes.
Phospholipids have a polar
head and nonpolar tails
• How would a phospholipid orient itself if
placed in water?
• The polar head would point into the
water; the tails would point away from
the water.
Cell membranes are formed
from lipid bilayers
• The polar heads point into
the cell, and outward, into
the cell's environment.
The nonpolar tails point
toward one another.
• Both phospholipids and
glycolipids can form lipid
bilayers.
Amino Acids
• Amino acids combine a carboxylic acid
group, an amine group, and a
hydrocarbon group (R) in a single
molecule.
• Amino acids can polymerize to form
proteins.
Common amino acids
• The 20 amino acids in the following
table are all common in living
organisms. They all combine a
carboxylic acid group, an amine group,
and a hydrocarbon group in a single
molecule.
• Amino acids react with incredible variety
to form proteins. These are considered
to be the 20 "essential" amino acids.
Zwitterion Formation
• Common to write amino acids with an intact
carboxyl (-COOH) group and amino (-NH2)
group but actual structure is ionic and depends
on the pH.
• The carboxyl group loses a proton (carboxylate
ion), and the amino group is protonated
(ammonium ion) = a dipolar ion or a zwitterion.
Protein structure is
expressed at four levels
• Proteins are made up of amino acid
sequences. The sequences organize into
recognizable shapes: pleated sheet, helix,
random coil. These structures fold into a
polypeptide chain that is ultimately arranged
in a distinct position with respect to one or
more other polypeptide chains.
• The four levels of structure allow proteins to
display extremely specific properties in living
organisms.
Proteins
• Proteins constitute more than the 50% of cells' solid
matter.
• Proteins are the more complex and functionally
more versatile among biomolecules because proteins
form structures like membranes, micro fibers,
skeletons, cilia, flagellums, etc., as for functions like
storage of energy, transportation of other substances,
signaling, protection, hormonal functions, etc.
• Proteins also are a critical part of all
metabolic processes because they work as
enzymes, which are proteins that selectively
accelerate or slow down chemical reactions.
• Important proteins for living beings are
enzymes, hormones, Collagen, Chlorophyll
and Hemoglobin.
• Proteins are formed by sub units called amino
acids. Amino acids are organic molecules
composed by two groups, one carboxyl group and
one amino group. The general formula for an
amino acid is as follows: C2H4O2N-R
• R means a chain of one or more atoms of Carbon,
which can combine with other elements, as H, O,
P and S, but that are not part of the carboxyl
group.
• There are 20 amino acids in nature from
which all proteins are built. Polymers
constructed by two or more amino acids,
joined by peptide bonds, are called
polypeptides.
Constituents of
nucleic acids
Formation of Nucleic Acids
• Flowchart showing the formation of a nucleic acid
starting from a sugar and an amine base.
Block diagram of DNA
• DNA consists of nucleotide units
bonded in a specific pattern. Each
nucleotide is composed of a sugar, a
phosphate group, and a base.
• The nucleotides join together through
the phosphate groups. The sugar is
deoxyribose.
A codon is a sequence of
three nucleotides
• Codons are three-nucleotide sequences
that code for an amino acid.
• Sequences of codons in a DNA
molecule make up the genes.
Portion of a nucleic acid
chain
RNA Polymer
• Nucleic acids are assembled on a backbone
made up of ribofuranoside units linked by
phosphate esters.
• Notes DNA and RNA each contain four
monomers, called nucleotides that differ in
the structure of the bases bonded to the
ribose units.
Ribonucleotides