Transcript I. The Structure and Function of Macromolecules

I. The Structure and Function
of Macromolecules
A. Macromolecule- Large molecules, some with
molecular weights exceeding 100,000 Daltons
1. Macromolecules are composed of polymers.
Chains of similar subunits
2. Monomers- individual subunits that make up
polymers
3. Polymers and molecular Diversity
a) All macromolecules are composed of 40-50 of the
same monomers
b) All proteins in all organisms are made of the same 20
amino acids. Just as 26 letters make all words
4. Making a Breaking Polymers
a) Condensation Reaction- usually occurs
between –OH groups of two monomers.
H2O is removed linking the monomers
with an oxygen bridge
b) Hydrolysis- breaking apart polymers at
their oxygen bridge by adding H2O which
results in two monomers
B. Carbohydrates- sugars and starches that serve
as important sources of fuel and structural
components
Carbohydrates
1. Monosaccharides- single
sugars with 3-6 carbons.
(Glucose, Fructose,
Galactose)
2. Disaccharides- two
monosaccharides joined
in a condensation reaction
3. Polysaccharides- many
single sugars joined
together
Types of Polysaccharides
a) Starch- storage form of carbohydrate in
plants. (Spiraling 1-4α glycosidic bonds)
b) Glycogen- Storage form of carbohydrates
in animals. (Spiraling, highly branched, 14α glycosidic bonds)
c) Cellulose- Structural polysaccharide in
plants. (Straight polysaccharide with 1-4β
glycosidic bonds)
4. Modified Carbohydrates
A) Chitin- main
component of the
exoskeletons of
arthropods. Contains a
monosaccharide
derivative glucosamine
Lipids
Animal Fat
Plant Oils
Waxes
C. Lipids- molecules
used to store energy
in organisms as well
as structural
materials. Made of
C, H, O. Less oxygen
than in carbohydrates.
Twice the amount of
energy. Soluble in
non-polar solvents
1. Neutral Fats- 1 glycerol with
fatty acid chains
Types of Lipids
a) Saturated fat- Solid at room temperature.
Many hydrogen. No double bonds
between carbons. Animal fats. Cause
arteriosclerosis.
b) Unsaturated and Polyunsaturated FatOils. Liquid at room temperature.
Double bond between some of the
carbons. 2 essential fats are oleic and
linoleic acid. These cannot be
synthesize by the body but must be in
the diet
2. Phospholipid-
important constituents of the cell
membrane made of a glycerol and 1-2 fatty acid
chain with the glycerol bonded to a phosphate
group. Contains a hydrophilic and hydrophobic
end
Other Lipids
3.Carotenoids- red and yellow plant pigments
that play a role in photosynthesis
A) splitting the orange plant pigment carotene
yeilds a retinol molecule
B) Retinol molecules play an important role as
photoreceptors in eyes
4. Steroids- class of compounds with four
interlocking rings to form many
biologically important molecules
(Cholesterol, bile salts, hormones etc….)
D. Proteins- all enzymes, some hormones
and many structural components of the cell
are proteins.
1. Subunit Structure
(Protein monomer = Amino Acid)
a) Amino acids are composed of an amino group
(-NH2) and an acidic carboxyl group but
different r groups
R group
Amino
group
Carboxyl
group
b) The “R” group determines the identity of the
amino acid
Amino Acids with Hydrophobic Side
Groups
Note the methyl groups at the bottom of the chains
Amino Acids with Hydrophilic Side
Groups
Note the charged or polar groups at the bottom of the chains
And Some Amino Acids are in
Between
Hydrophobic and Hydrophilic regions influence protein shape.
C) Amino acids can serve as acids or bases
and are therefore considered buffers
D) Amino acids are linked by a condensation
reaction and form peptide bonds
E) When many amino acids are joined, a
polypeptide is formed
2. Levels of Protein Structure
A) Primary- Linear sequence of amino acids joined
by peptide bonds in a condensation reaction
B) Secondary- coiling and pleating of amino acid
chains (α helixes or β pleats) stabilized by
hydrogen bonds
C) Tertiary- overall shape caused by the folding or
twisting of the secondary structure
D) Quaternary Intertwining of multiple
polypeptides to produce a highly specific 3D
shape
3. Importance of Proteins
a) Proteins are the most abundant molecule in living cells.
Functionally diverse, They control all life functions
Class
Function
Example
A) Enzymes. Control Chemical Reactions. Maltase
B) Structure. Building material of cells. Collegen
C) Contractile. Movement.
Actin and myosin
D) Hormones. Regulatory chemicals.
Insulin
E) Transport. Ship important substances hemoglobin
F) Defense
Fight Disease
antibodies
c) Proteins are sensitive and may denature (change shape) and
become non functional. Heat, pH and metals all can cause
denaturation
E. Nucleic Acids- large complex molecules formed
of smaller smaller units called nucleotides
1. Nucleic Acid structure (monomer = nucleotide)
a) Nucleotide consists of a sugar a phosphate group and a
nitrogen base
b) Sugars:
1) Ribose in RNA
2) Deoxyribose in DNA
c) Bases:
1) Purines (2 rings) Adenine and Guanine
2) Pyrimidines (1 ring) cytosine and Thymine
Nucleic Acids
2. DNA structure is a double helix with the
base pairing of Thymine & Adenine and
Cytosine & Guanine.
3. RNA structure is a single spiral with
Uracil replacing thymine.
4. Nucleic Acid Function
a) DNA carries the genetic code. The information
for constructing proteins
b) RNA Carries the genetic code to the ribosome.
c) Adenosine Triphosphate (ATP) supplies energy
to the cell
d) Other Nucleotides and dinucleotides are electron
transport molecules and energy carriers
– GTP, UTP, CTP
– dGTP, dATP, dCTP, dTTP
– AMP, NAD+, NADP, FAD