Download The Structure and Function of Macromolecules

The Structure and
Function of
Macromolecules
II. Classes of Organic
Molecules:
• What are the four classes
of organic molecules?
I. Polymers
• What is a polymer?
• Poly = many; mer = part. A
polymer is a large molecule
consisting of many smaller
sub-units bonded together.
• What is a monomer?
• A monomer is a sub-unit of a
polymer.
A. Making and Breaking
Polymers
• How are covalent linkages
between monomers formed in
the creation of organic
polymers?
• Condensation or dehydration
synthesis reactions.
• Monomers are covalently linked
to one another through the
removal of water.
Condensation Synthesis
Hydrolysis
1. Structure of
Monosaccharides
• Classified according to the size of
their carbon chains, varies from 3 to
7 carbons.
Triose = 3 carbons
Pentose = 5 carbons
Hexose = 6 carbons
• In aqueous solutions many
monosaccharides form rings:
2. Structure of Disaccharides
• Double sugar that consists of
2 monosaccharides, joined
by a glycosidic linkage.
• What reaction forms the
glycosidic linkage?
Examples of Disaccharides:
Lactose = glucose +
galactose
Sucrose = glucose + fructose
3. Polysaccharides
• Structure: Polymers of a few hundred
or a few thousand monosaccharides.
• Functions: energy storage molecules
or for structural support:
B. Lipids
• Structure: Greasy or oily
nonpolar compounds that are
insoluble in water
• Functions:
1. Structure of Fatty Acids
• Long chains of mostly carbon
and hydrogen atoms with a COOH group at one end.
• When they are part of lipids,
the fatty acids resemble long
flexible tails.
Saturated and Unsaturated
Fats
• Unsaturated fats :
• Saturated fats:
Saturated
fatty acid
Saturated
fatty acid
Unsaturated
fatty acid
2. Structure of Triglycerides
• Glycerol + 3 fatty acids
• 3 ester linkages are formed between a
hydroxyl group of the glycerol and a
carboxyl group of the fatty acid.
3. Phospholipids
• Structure: Glycerol + 2 fatty
acids + phosphate group.
Phospholipids in Water
4. Waxes
• Function:
• Lipids that serve as coatings
for plant parts and as animal
coverings.
5. Steroids
• Structure: Four carbon rings with no
fatty acid tails
• Functions:
• Component of animal cell membranes
• Modified to form sex hormones
C. Proteins
• Structure: made of C.H.O, +N.
• Polypeptide chains
• Consist of peptide bonds
between 20 possible amino
acid monomers
• Have a 3 dimensional
globular shape
1. Functions of Proteins
2. Structure of Amino Acid
Monomers
Properties of Amino Acids
• Grouped by polarity
• Variable R groups (side chains) confer
different properties to each amino acid:
3. Primary Structure
• Unique sequence of amino acids in a
protein
• Slight change in primary structure can alter
function
• Condensation synthesis reactions form the
peptide bonds between amino acids
4. Secondary Structure
• Repeated folding of protein’s polypeptide
backbone
• stabilized by H bonds between peptide
linkages in the protein’s backbone
• 2 types, alpha helix, beta pleated sheets
5. Tertiary Structure
• Irregular contortions of a protein
due to bonding between R groups
• Weak bonds:
–H bonding between polar side
chains
–ionic bonding between charged
side chains
–hydrophobic and van der Waals
interactions
Strong Bonds:
Disulfide bridges form strong
covalent linkages
5. Quaternary Structure
• Results from interactions among 2 or
more polypeptides
Factors That Determine Protein Conformation
• Occurs during protein synthesis within
cell
• Depends on physical conditions of
environment
–pH, temperature, salinity, etc.
• Change in environment may lead to
denaturation of protein
• Denatured protein is biologically
inactive
• Can renature if primary structure is not
lost
D. Nucleic Acids
• Two kinds:
–DNA:
double stranded
makes up genes which code
for proteins
–RNA:
functions in actual synthesis
of proteins coded for by DNA
is made from the DNA
1. Nucleotide Monomer
Structure
• Both DNA and RNA are composed of
nucleotide monomers.
• Nucleotide = 5 carbon sugar,
phosphate, and nitrogenous base
Deoxyribose in DNA
Ribose in RNA
2. Building the Polymer
• Phosphate group of one nucleotide
forms strong covalent bond with the
#3 carbon of the sugar of the other
nucleotide.
3. Functions of Nucleotides
• Monomers for Nucleic Acids
• Transfer chemical energy
from one molecule to another
(e.g. ATP)
Summary of the
Organic Molecules: