CARBOHYDRATES
Examples: sugar, starch, cellulose and glycogen
Primary functions: provide and store energy, provide structural support
Formed from: Carbon, Hydrogen and Oxygen in a ratio of 1:2:1.
Most sugars end with the suffix "-ose".
A. Monosaccharides (single molecule sugars)
A single molecule sugar is called a monosaccharide (aka simple sugar). Monosaccharides are the
monomers of carbohydrates, meaning that they are the smallest molecule into which carbohydrates can be
broken down. The prefix “mono” means one. The six carbon monomers below all have the same
molecular formula C6H12O6, but have different molecular structures due to a different arrangement of
atoms. Three common six carbon monosaccharides are glucose, fructose, and galactose. Examine the
structural formulas of these three sugars (Figure 6-1).
While most sugars have 6 carbons and are formed in rings, sugars may have 3, 4 or 5 carbons, and may be
formed in straight chains or branches as well as rings.
(see over)
B. Disaccharides (double molecule sugars)
Two monosaccharide sugar molecules can join chemically to form a larger carbohydrate molecule called a
double sugar, or disaccharide. The prefix “di-“ means two. By chemically joining a Glucose molecule
with a Fructose molecule, a double sugar called Sucrose (table sugar) is produced and a molecule of water
is released.
The process of combining the two monosaccharides is called dehydration synthesis -- making a new
molecule out of two while taking a water molecule out. To break this new molecule back into its two
original molecules, a molecule of water must be added. This is called hydrolysis -- the adding of a water
molecule. ALL organic molecules are put together and broken down by these same processes.
Different disaccharide molecules can be made by joining other monosaccharides in different
combinations. For example, by chemically joining a Glucose molecule with another Glucose molecule, a
double sugar called Maltose is formed. Galactose and Glucose together make Lactose, the sugar found in
milk.
C. Polysaccharides
Just as double sugars were formed from two single sugar molecules, polysaccharides are formed when
many single sugars are joined chemically. The prefix “poly-” means many. Starch, Glycogen, and
Cellulose are the three most common polysaccharides in biology. They consist of long chains and/or
branches of Glucose molecules joined together through dehydration synthesis.
Cellulose
LIPIDS
Examples: Fats, Oils, Waxes, and Steroids.
Primary Functions: store energy (fats and oils), provide for chemical communication (steroids), and
to provide protection (waxes and oils).
Formed of: Carbon, Hydrogen and Oxygen
Most lipids are formed with two types of subunits: Glycerol and fatty acids chains. These are called the
'monomers' of lipids, 'mono' meaning "one". These monomers are made of Carbon, Hydrogen and
Oxygen (CHO). For most lipids, there will be one Glycerol molecule with 3 fatty acid chains attached.
See the diagram below to see how a water molecule is released each time a fatty acid chain is attached to
the Glycerol molecule. This is called dehydration synthesis: the making of a new molecule
accompanied by the release of a water molecule. To break this fat down, then, a water molecule would
need to be added. This is call hydrolysis. These two processes are used every time a new organic
molecule is created by combining others, or when an organic molecule is broken down into its monomers.
Butyric Acid
(one of the fatty acids)
Water molecule
removed here
glycerol
When the fatty acid chains consist of only single carbon bonds the lipid is called a saturated fat. If the
chains have any carbons double-bonded together, it is called an 'unsaturated fat'. If there are many
double-bonded carbons, it is called a 'polyunsaturated fat'.
Example of a polyunsaturated fat
Lipids are hydrophobic (water hating). One type of lipid, a phospholipid, is used in all cell membranes.
This water-hating habit allows the cell membrane to control what goes and in out of the cell.
Steroids are formed differently from other lipids; their carbons are usually formed into rings. Hormones
are steroidal lipids. These special lipids can pass through the cell membranes.
Example of structure of a steroid
PROTEINS
Examples: muscle tissue, enzymes
Formed of: Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulfur (CHONS)
Functions: support, transport, communication, reaction speeds, cell growth
Most end with the suffix "-ase".
Proteins are compounds made of small carbon monomers called amino acids. The order and number of
amino acids determines which protein is made. There are 20 different amino acids and they all share
similar structures.
Radical or
Variable
Group
Basic
Amino
Acid
Structure
Amino
Group
(NH2)
Carboxyl Group (COOH)
C
Central carbon atom
H
2 examples of Amino Acids
Folding of proteins
Notice that hooking two amino acids together will
release 2 H atoms and 1 oxygen atom (H2O)
To form proteins, amino acids are linked into a chain. As each amino acid is added, a water molecule is
released This is called dehydration synthesis. When the chain has reached its appropriate length, it is
then folded into the unique shape of the protein. A protein can include both fan folded sections and helix
(or spring shaped) sections.
NUCLEIC ACIDS
Nucleic acids: formed of monomers called nucleotides, made up of Carbon, Hydrogen, Nitrogen, Oxygen
and Phosphorous atoms (CHNOP). Two basic types of nucleic acids: DNA, and RNA.
There are 5 different nucleotides. They share the same basic structure and are known as the 'bases' that
make up DNA and RNA (see below).
DNA (deoxyribonucleic acid) : a double strand of nucleotide chains in the shape of a double helix. Each
of its nucleotides are composed of one of the four bases: Adenine (A), Thymine (T), Guanine (G)and
Cytosine (C); a five-carbon sugar called deoxyribose; and a phosphate group.
RNA (ribonucleic acid): differs from DNA in that it is single stranded, uses the sugar ribose, and
substitutes the base Uracil (U)for Thymine.
A single strand of nucleic acid is formed when the phosphate group of a nucleotide attaches to the sugar
group of another nucleotide. This then leaves the bases free, as in DNA, to connect to each other with
either double or triple hydrogen bonds. (see diagram below)
The function of DNA and RNA is to store and transmit genetic information. The DNA that carries the
genetic code of the organism is found only in a cell's nucleus; it makes up the cell's chromosomes. (There
is another type of DNA; we will learn about that later) There are 3 types of RNA: mRNA (messenger
RNA), rRNA (ribosomal RNA) and tRNA (transfer RNA), (We will learn much more about these RNAs
later as well.)
Basic Structure of a Nucleotide
Adenine, Thymine,
Guanine, Cytosine or
Uracil
Deoxyribose in DNA, Ribose in RNA
Connecting of Bases to form
DNA, a double chain
Connecting of
nucleotides to form
a single chain of
nucleic acid
4 Classes of Organic
Compounds
All
Contain
Carbon
Monomers (M)
(Building Blocks)
(Building
Blocks
Macromolecules
CHO
CHONP
Carbohydrates
Nucleic Acids
M=Sugars
M=
Nucleotides
starch
es
DNA
cellulose
RNA
glycogen
CHONS
CHO
Lipids
M=
Fatty Acids and
Glycerol
Proteins
M=
Amino Acids
fats
oils
waxes
enzymes
muscle fibers
cytoskeleton
steroids