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CHAPTER 5
The Structure and Function
of Macromolecules
What
Macromolecules
Can you see in
This picture?
What makes you- you… or
any organism on Earth what
it is? What four types of
molecules are cells and
organisms composed of?
Water,
minerals,
vitamins
Protein
Carbohydr
ates
Lipids
Big Idea 1: The process of evolution drives
the diversity and unity of life.
The origin of living systems is
explained by natural processes.
Molecular and genetic evidence
from extant and extinct organisms
indicates that all organisms on
Earth share a common ancestral
origin of life.
1. Scientific evidence includes
molecular building blocks that are
common to all life forms: glucose,
amino acids, nucleotides, fatty
acids + glycerol, ATP> ADP
2. Scientific evidence includes a
common genetic code: DNA 
RNA  Protein
Nucleic
Acids
Lipids
PROTEIN
Carbohydrates
Autotrophsphotosynthesis
Heterotrophsconsume others
Carbon dioxide
from atmosphere
Carbohydrates
Water from soil
Protein
Nitrogen
Sulfur
Phosphorus
In water
Lipids
Photons + 6CO2 + 6H20 --> C6H12O6 + 6O2
Nucleic Acids
C6H12O6 + 6 02 --> 6 CO2 + 6 H20 + 38 ATP
POLYMERS (macromolecules) &
MONOMERS (building blocks)
PROTEINS
Amino
Acids
(20 kinds)
NUCLEIC
ACIDS
Nucleotides
(4 kinds= A,T,G,C)
CARB
OHYDRATES
Monosaccharides
Many… (glucose)
LIPIDS*
(not a true
macromolecule)
Glycerol
Fatty Acids
(many)
POLYMER =
A long molecule made of identical
monomers linked together with
covalent bonds.
Ex.
DNA, RNA, Protein, Polysaccharides
THE CONDENSATION REACTION
aka DEHYDRATION SYNTHESIS
condensation rxn
dehydration synthesis rxn
• A way to connect monomers together
to build a larger molecule… polymer
• H is taken off of one monomer
• OH is taken off a second monomer &
• the monomers form a covalent bond.
• Water is produced.
• Covalent bond is formed between
monomers.
HOW WOULD YOU DO THE
OPPOSITE REACTION???
What is it called?
Figure 5.2 The synthesis and breakdown of polymers
THE HYDROLYSIS REACTION
dissociation
The hydrolysis rxn =
• Hydro “water” + Lysis “to cut”
• Breaking C-C bonds within a
polymer using water.
• Split a water & add H and OH back
to the monomers.
Big Idea 4: Biological systems interact, and
these systems and their interactions
possess complex properties.
• Interactions within biological systems lead to complex
properties.
• Structure and function of polymers are derived from the
way their monomers are assembled.
1. Carbohydrates are composed of sugar monomers whose
structures and bonding with each other by dehydration
synthesis determine the properties and functions of the
molecules.
Ex. cellulose versus starch.
• ✘ The molecular structure of specific carbohydrate
polymers is beyond the scope of the course and the AP
Exam.
CARBOHYDRATES
• Contain the elements: C, H, O
• Molecular ratio of elements: 1:2:1
1. MONOSACCHARIDES =
simple sugars
PROPERTIES:
• Hydrocarbon chains with hydroxyl groups
• Polar molecules
• General formula = (CH2O)n (n=3-7)
• Role = fuel for cellular work (cellular
respiration)
• Serves as the carbon skeleton for other types of
monomers (ex. Amino acids)
• Component of nucleotides (ribose/deoxyribose)
THE 3 MOST IMPORTANT:
Hexose sugars: C6H12O6
1. Glucosestraight chain ALDEHYDE
2. Galactosestraight chain ALDEHYDE
3. FructoseStraight chain KETONE
Question:
These were branched
diagrams… but when
dissolved in water all three
take on what form?
Answer: Ring
Q: how are these forms different???
A: Oxygen is in the “ring”… functional grps.
Notice the bond is between the carbonyl on
carbon 1 and the hydroxyl on carbon 5.
what is the importance of glucose?
ATP
Main fuel source to
generate energy
(ATP) via cell
respiration in the
mitochondria
ADP
2. DISACCHARIDESdouble sugar
• Comprised of: 2 monosaccharides
• Bonded together via: a condensation rxn
glycosidic linkage
2. DISACCHARIDESdouble sugar
Types:
a) Sucrose =
glucose + fructose
b) Maltose =
glucose + glucose
c) Lactose =
glucose + galactose
Illustrative examples.
SUCROSE
Figure 5.5x Glucose monomer and disaccharides
Glucose monomer
Sucrose
Maltose
3. POLYSACCHARIDEScomplex carbohydrates
•
a)
•
•
Polymerization
STARCHES =
glucose monomers bound repeatedly;
Short term energy storage for plants
inside plastids (ex. amyloplast)
1) Amylose (unbranched)
2) Amylopectin (branched)
b) GLYCOGEN =
•
•
highly branched & coiled glucose
monomer chains
Short term energy storage for
animals inside liver and muscle
cells.
c) CELLULOSE =
• Chains of beta glucose
monomers
• Every other glucose is
upside down in the
polymer
• Straight chain (fibers),
never branched
• Cell walls of plantsstructure only.
Figure 5.7x Starch and cellulose molecular models
 Glucose
 Glucose
Cellulose
Starch
Why do animals have difficulty
digesting cellulose?
• Animals lack the necessary enzyme
to break the Beta linkages
• Cows overcame this problem by
harboring bacteria that can break
down cellulose.
Figure 5.x1 Cellulose digestion: termite and Trichonympha
Termites can do it to because of a symbiotic relationship
with this kind of protazoan…. Trichonympha.
d) CHITIN
• Similar to cellulose (also contains N)
• Used in cell walls of fungi and in the
exoskeletons of arthropods like:
- insects
- spiders
- scorpions
- lobsters, shrimp
“chitin is excitin’! “
LIPIDS
Contain the elements:C, H, O
Properites:
• Little or no affinity for water
(hydrophobic)
• Consist mostly of hydrocarbons and
some polar bonds with oxygen.
• Smaller than true macromolecules
(nucleic acids, proteins, carbohydrates)
1. Fats and Oils
• One molecule of
fat is made of:
- glycerol
- fatty acids
• Triglyceride =
- three fatty acids
- one glycerol
long hydro-carbon
chains are why fats
are hydrophobic!
nonpolar
GLYCEROL STRUCTURE
• Alcohol
• 3 carbon’s
• each w/ hydroxyl grp.
FATTY ACID STRUCTURE
• Acid
• Long carbon skeleton
(16-18 C’s long)
• carboxyl grp. at one end
Figure 5.11 Examples of saturated and unsaturated fats and fatty acids
No double bonds
between carbon
atoms.
Hydrogen bonded as
much as possible
onto the carbon
skeleton.
“Saturated with
hydrogens” =
SATURATED FAT
Figure 5.11 Examples of saturated and unsaturated fats and fatty acids
Double bonds exist
between carbon
atoms.
Formed by the
removal of hydrogen
from the carbon
skeleton.
“Not saturated with
hydrogens” =
UNSATURATED FAT
WHICH IS HEALTHIER TO COOK WITH/ EAT???
Saturated Fats
BAD
Solid at room temp
Animal fats
Unsaturated Fats
GOOD
Liquid at room temp
Plant & Fish fats
Diets rich in saturated fats
contribute to Atherosclerosis• Cardiovascular
disease
• Plaques develop
inside blood
vessels blocking
flow and making
them inelastic.
- heart attack,
stroke,thrombosis
why are fats perfect for
storage and energy?
• They are LIGHT! Which is important
for animals & seeds.
• 1 gram of fat stores more than twice
as much energy as a gram of
polysaccharide.
2. PHOSPHOLIPIDS
• The main component of cell
membranes.
• Are comprised of :
a) two fatty acids
b) glycerol
c) phosphate group (negative)
& various attachments
• glycerol/phosphate is the
“HEAD”
• two fatty acids are the “TAILS”
Phospholipid’s Key property:
• Ambivalent towards water.
• When placed in water they self
assemble into clusters that
shield the hydrophobic tails
from the water.
- micelle
- phospholipid bilayer
- coacervates
3. STEROIDS
• Basic structure:
four fused rings.
• Vary in the
functional groups
attached to the
rings.
EXAMPLES:
A. CHOLESTEROL
1) Component of animal cell
membranes.
2) Precursor to other
steroids
sex hormones:
B. ESTROGEN
C. PROGESTERONE
D. TESTOSTERONE
stress hormone:
E. Cortisol
F. ANABOLIC steroidsEx. TESTOSTERONE
promotes muscle growth and
development
End. (part 1)
PROTEINS
• Contain the elements:
C,H,N,O
• The building blocks are:
AMINO ACIDS.
• Account for > 50% of the
dry weight of most cells.
• Proteios, “first place”
Fun fact:You should eat
9 grams of protein for
every 20 pounds of
body weight.
Protein functions:
• Structural support
– Keratin, collagen,
cytoskeleton of cells
• Storage
DEFENSE
Ex. Antibodies
– ex. albumin of egg whites
store amino acids
• Transport of substances
– Membrane tunnels
• Signaling
– Hormones like insulin,
oxytocin, glucagon
• Movement
– Contractile proteins like SARCOMERE functional unit
of a muscle cell… made of
actin and
Actin and Myosin proteins
ENZYMES
• Biological molecules that catalyze
(increase the rates of) chemical reactions.
• The set of enzymes made in a cell
determines the metabolic pathways that
will occur there.
AMINO ACID STRUCTURE
•
•
•
•
•
asymmetric carbon
Amino group
Carboxyl group
Hydrogen atom
R group (variable)
- side chain
- 20 different ones
- Polar, nonpolar,
acidic, or basic
1.Proteins are POLYPEPTIDES
The peptide bond: Covalent bond between
• the carboxyl group of one amino acid and
• the amino group of another
• Formed by a condensation rxn.
Proteins have an amino (NH2) end and a
carboxyl (COOH) end, and consist of a linear
sequence of amino acids connected by the
formation of peptide bonds by dehydration
synthesis between the amino and carboxyl
groups of adjacent monomers.
2. SHAPES OF PROTEINS
The specific order of amino acids in a polypeptide
(primary structure) interacts with the environment to
determine the overall shape of the protein, which also
involves secondary tertiary and quaternary structure
and, thus, its function.
The four levels of protein structure.
2. SHAPES OF PROTEINS
A. PRIMARY STRUCTURE- unique sequence of
amino acids (like the order of letters in a very long
word)
A. SECONDARY STRUCTURE- coiled and folded
patterns due to hydrogen bonds. Occurs between
atoms attached to the backbone- but not R group.
1) a-helix- coil held by hydrogen bonding between every
4th amino acid.
Ex) keratin
2) B-pleated sheet- cross-linkage between two or more
regions that lie parallel to each other.
Ex) silk
C. TERTIARY STRUCTURE
irregular contortions from
interactions between R-groups
(side chains)
1) hydrophobic/ van der waals
interactions (nonpolar Rgroups)
2) hydrogen bonding
(polar R-groups)
3) disulfide bridge (s-s, from SH R-groups)
4) ionic bonding (+ & -)
TERTIARY STRUCTURE
The R group of an amino acid can be categorized by
chemical properties:
hydrophobic
hydrophilic and
ionic.
and the interactions of these R groups determine
structure and function of that region of the protein.
D. QUATERNARY
STRUCTURE
1) Triple Helix- three
alpha helixes
ex. Collagen…
rope-like
2) Globular- two or
more polypeptide
chains
ex. Hemoglobin…
a & B chains
Figure 5.24 Review: the four levels of protein structure
What happens when a protein
becomes denatured?
• It loses its native conformation.
• Is thus… biologically inactive.
• ENVIRONMENT: pH, salt concentration, high
temperature, can unravel the protein.
• Yes, proteins can become “renatured”.
Table 5.2 Polypeptide Sequence as Evidence for Evolutionary Relationships
NUCLEIC ACIDS:
DNA & RNA (S&F)
DNA molecule is
comprised of a series of
nucleotides that can be
linked together in
various sequences; the
resulting polymer
carries hereditary
material for the cell,
including information
that controls cellular
activities.
Q: What is a double helix?
A: two polynucleotides that spiral around
an imaginary axis. Double stranded.
Q: What holds the double helix together?
A: hydrogen bonds between nitrogenous
bases hold the 2 strands together.
Q: What are base pairs?
A: bases that are compatible w/ e/o…
that hydrogen bond to eachother.
1) Adenine - Thymine (2 H bonds)
2) Guanine - Cytosine (3 H bonds)
Rosalind Franklin
James Watson and Francis Crick
1.DNA
•
•
•
Unit of heredity. Enables living things to reproduce their
components from generation to generation.
Directs protein synthesis.
NUCLEOTIDE is the chemical building block
A. 5 carbon sugar: deoxyribose
B. Phosphate group
C. Nitrogen bases
1. Adenine, Guanine
(purines: 2 rings)
2. Cytosine, Thymine
(pyrimidines: 1 ring)
Figure 5.29 The components of nucleic acids
Figure 5.30 The DNA double helix and its replication
DNA is self-replicating
Complementary base
pairing makes the precise
copying of DNA possible.
2. RNA
* Molecules that function in the
synthesis of proteins!
•
5 carbon sugar: RIBOSE
•
Phosphate group
•
Nitrogenous bases
1. Adenine, Guanine
2. Cytosine, URACIL
* RNA is a single stranded
molecule!
W/ your Partner
Compare and contrast DNA with RNA
in terms of:
1) Structure
2) Function
3) Evolutionary Relationships
• THE END