CHAPTER 5:

STRUCTURE AND FUNCTION

OF MACROMOLECULES
SPECIFIC OBJECTIVES

 1.) List the 4 major classes of

macromolecules and identify their general
 characteristics.
 2.) Describe what occurs during a general
condensation (dehydration) and hydrolysis
 reaction in the formation and breakdown of
polymers.
 3.) Name the specific monomers in each
class of macromolecule and the name of
the
 bonds between them when polymers are
formed.
 4.) Distinguish between mono-, di- and
poly-saccharides.
 5.) Describe the structure of fats,
phospholipids and steroids.
 6.) Distinguish between saturated and
unsaturated fats.
 7.) List and describe the major
components of all amino acids. Explain
how amino
 acids differ due to the chemical
properties of their R groups.
 8.) Discuss what determines the 4 levels
of protein structure.
 9.) List conditions under which proteins
may be denatured.
 10.) List the major components of a
nucleotide and describe how these
monomers are
 linked to form a nucleic acid.
 11.) Briefly describe the 3-D structure of
DNA including the base pair rules.
 12.) Compare and contrast RNA and DNA.
POLYMERS – MOST MACROMOLECULES ARE
POLYMERS

A. Definition – Large molecule consisting of many

identical or similar subunits connected together

B. Monomer – Subunit or building block molecule

of a polymer

C. Macromolecule – Large organic polymer – 4

classes: carbohydrates, lipids, proteins, nucleic
acid
D. MAKING AND
BREAKING
POLYMERS
 1. POLYMERIZATION REACTIONS

 Chemical reactions
that link two or more
small molecules to
form larger
molecules with
repeating structural
units
2. CONDENSATION REACTIONS (DEHYDRATION SYNTHESIS)

 polymerization reactions during which monomers are covalently

linked, producing a net removal of a water molecule for each
covalent linkage

a. One monomer losses –OH, the other one loses –H

b. Requires energy and enzymes

3. HYDROLYSIS
 A reaction that breaks covalent bonds
between monomers by the addition of
water molecules

a. One monomer gains –OH, the other

gains –H
b. Digestive enzymes catalyze
hydrolytic reactions
LINKING MOLECULES
TOGETHER
 CARBOHYDRATES
Organic molecules made of sugars and
their polymers
A. MONOSACCHARIDE - SIMPLE SUGAR IN WHICH C, H, O
OCCUR IN RATIOS OF CH2O, CARBONS = 3-7
1. Major nutrient for cells, especially glucose

2. Produced through photosynthesis – store energy from the

sun

3. Aldehyde – terminal carbon forms a double bond with

oxygen

4. Ketone – carbonyl group within the carbon skeleton

5. Ring and linear forms – in aqueous solutions, many

monosaccharides form rings. Chemical equilibrium favors
ring structure
B. DISACCHARIDES - DOUBLE SUGAR THAT CONSISTS OF TWO
MONOSACCHARIDES JOINED BY A GLYCOSIDIC LINKAGE

1. Glycosidic linkage –
Covalent bond formed
by a condensation
reaction btwn 2 sugar
monomers

2. Maltose (glucose +
glucose)

3. Lactose (glucose +
galactose)

4. Sucrose (glucose +
fructose)
C. POLYSACCHARIDES- POLYMERS OF A FEW HUNDRED
OR THOUSAND MONOSACCHARIDES
1. Storage Polysaccharides – cells hydrolyze storage
polysaccharides into sugars as needed, alpha 1,4
linkages
a. Starch – Glucose polymer, plant storage
i. Stored in granules in plastids
ii. Amylase, unbranched
iii. Amylopectin, branched

b. Glycogen – glucose polymer, animal storage

i. Large polymer, highly branched
ii. Stored in muscle and liver vertebrates
POLYSACCHARIDES CONT.

2. Structural polysaccharides

a. Cellulose – linear unbranched polymer of D-glucose in

beta 1,4 linkages (-OH of C1 in up position)
i. Major structural component of plant cell walls

b. Chitin – amino sugar polymer

i. Exoskeleton in arthropods
ii. Found in cell walls of some fungi
LIPIDS – NONPOLAR
A. FATS - MACROMOLECULES CONSTRUCTED
FROM:

1. Glycerol – 3 carbon alcohol

2. Fatty Acid (carboxylic acid)

a. Carboxyl group (“head”) at one end – functions as an acid
b. Hydrocarbon carbon (“tail”) at other end, nonpolar, usually
16-18 C’s long

3. Ester linkage – Bond formed between the hydroxyl of

glycerol and the carboxyl of fatty acid by condensation

4. Triacylglycerol – A fat composed of three fatty acids bonded

to one glycerol by ester linkages (triglyceride)
5. CHARACTERISTICS OF FAT

a. Insoluble in water due to hydrophobic fatty acid

chains

b. Variation among fat molecules due to fatty acid

composition

c. Fatty acids may all be the same or different

d. Fatty acids vary in length

CHARACTERISTICS OF FAT CONT.
e. Saturated fat
i. No double bonds between C’s in the tail
ii. C’s bonded to maximum number of H’s
(saturated)
iii. Usually solid at room temperature
iv. Most animal fats

f. Unsaturated fat
i. One or more double bonds between C’s in tail
ii. Tail kinks at each C=C. So molecules do not pack
closely enough to solidify at room temperature
iii. Usually liquid at room temperature
iv. Most plant fats (oils)
CHARACTERISTICS OF FAT CONT.

g. Functions
i. Energy storage (9 Cal/g)
ii. Cushions vital organs in mammals
(kidneys)
iii. Insulates against heat loss
6. PHOSPHOLIPIDS - GLYCEROL, 2 FATTY
ACIDS, PHOSPHATE GROUP

a. Hydrophilic head (phosphate group)

b. Hydrophobic tail (fatty acids)

c. Major constituents of cell membranes

Phospholipid bilayer –
separates the inside of the cell from the outside of the cell,
only water and small ions can pass through
7. STEROIDS - FOUR FUSED CARBON RINGS WITH
VARIOUS FUNCTIONAL GROUPS ATTACHED
a. Cholesterol

i. Precursor to many other steroids including vertebrate sex

hormones and bile acids
ii. Component of animal cell membranes – stabilization and
rigidity
iii. Can contribute to atherosclerosis
 PROTEINS

Molecular tools for most cellular function – Consists of one

or more polypeptide chains folded and coiled into specific
conformations
A. POLYPEPTIDE CHAINS
– POLYMERS OF AMINO ACIDS THAT ARE ARRANGED IN A SPECIFIC
LINEAR SEQUENCE AND ARE LINKED BY PEPTIDE BONDS
B. FUNCTION
1. Structural Support
2. Storage (of amino acids)
3. Transport (e.g. hemoglobin)
4. Signaling (chemical messengers)
5. Cellular response to chemical stimuli (receptor
proteins)
6. Movement (contractile proteins)
7. Defense against foreign substances and disease –
causing organisms (antibodies)
8. Catalysis of biochemical reactions (enzymes)
C. PROPERTIES
1. Abundant – 50% or more of cellular dry weight

2. Vary extensively in structure – unique 3D shape

(conformation)

3. Made up of 20 amino acid monomers in

different amounts and combinations
D. AMINO ACIDS
- BUILDING BLOCK MOLECULES OF A PROTEIN

1. Structure – Asymmetric
carbon, alpha carbon,
bonded to:
a. Hydrogen atom
b. Amino group
c. Carboxyl group
d. Variable R group (side
chain) specific to each
aa
2. Grouped by properties of side chains
a. Nonpolar side groups – hydrophobic

b. Polar side groups – hydrophilic

i. Uncharged polar
ii. Charged polar
iii. Acidic side groups – dissociated carboxyl group – negative
charge
iv. Basic side groups – amino group w/extra proton –
positive charge
E. POLYPEPTIDE CHAINS
- POLYMERS FORMED WHEN AMINO ACIDS POLYMERIZE
1. Peptide bond –
Covalent bond
formed by a
condensation
reaction that links
the carboxyl group of
one amino acid to
the amino acid group
of another

2. Backbone = - N – C –
C–N–C–C–N-
F. PROTEIN CONFORMATION
– 3D SHAPE OF A PROTEIN – FUNCTION IS DEPENDENT
ON STRUCTURE

1. Protein Structure
a. Primary
b. Secondary
c. Tertiary
d. Quarterary
a. PRIMARY STRUCTURE
- UNIQUE SEQUENCE
OF AMINO ACIDS

i. Determined by genes
ii. Slight change can
significantly affect
conformation
B. SECONDARY STRUCTURE
- REGULAR, REPEATED COILING AND FOLDING OF A
PROTEIN’S POLYPEPTIDE BACKBONE

i. Contributes to overall structure

ii. Stabilized by H bonds between peptide linkages in the
protein backbone

iii. Alpha Helix – helical coil stabilized by H-bonding between

every 4th peptide bond
a) Found in fibrous proteins (keratin, collagen) for most of their
length and some portions of globular proteins
iv. Beta Pleated Sheets – sheets of antiparallel chains folded
into accordion pleats
a) Make up dense core of globular protein and major portion of
some fibrous proteins
Hydrogen bonds
C. TERTIARY STRUCTURE
- IRREGULAR CONTORTIONS OF A PROTEIN DUE TO BONDING
BETWEEN SIDE CHAINS (R GROUPS); THIRD LEVEL OF PROTEIN
STRUCTURE SUPERIMPOSED UPON PRIMARY AND SECONDARY
STRUCTURE

i. Weak interactions
a) H-bonding between polar side chains
b) Ionic bonds between charged side chains
c) Hydrophobic interactions between nonpolar side
chains in protein’s interior

ii. Covalent linkages – Disulfide bridges form

between two cysteine monomers – strong bond
D. QUATERNARY
STRUCTURE
- STRUCTURE THAT RESULTS
FROM THE INTERACTION
AMONG POLYPEPTIDES IN A
SINGLE PROTEIN
Folding due to hydrophilic and
hydrophobic amino acids
G. DENATURATION
- A PROCESS THAT ALTERS A PROTEIN’S
NATIVE CONFORMATION AND BIOLOGICAL
ACTIVITY – CAUSED BY:
1. Transfer to an organic solvent (nonpolar)

2. Chemical agents can disrupt H bonds, ionic bonds,

and disulfide bridges

3. Excessive heat

4. Inappropriate pH
V. Nucleic Acids
- Protein conformation is determined by primary structure.
Primary structure is determined by genes (DNA sequences)
A. DNA – DEOXYRIBONUCLEIC
ACID
1. Contains coded info that programs all cell activity

2. Contains directions for its own replication

3. Is copied and passed from 1 generation of cells to another

4. In eukaryotic cells, found primarily in the nucleus

5. Genes direct the synthesis of RNA

B. RNA – RIBONUCLEIC ACID
1. Functions in the actual synthesis of proteins
coded for by DNA

2. Sites of protein synthesis are on ribosomes in

the cytoplasm

3. mRNA carries genetic message from nucleus to

cytoplasm
C. NUCLEOTIDES
– BUILDING BLOCKS OF A NUCLEIC ACID
1. Pentose – 5-carbon sugar (RNA/ribose; DNA/deoxyribose)

2. Phosphate group attached to a number 5 carbon of the

sugar

3. Nitrogenous base
a. Pyrimidine – six-membered ring made up of carbon and
nitrogen atoms
i. Cytosine (C)
ii. Thymine (T) – found only in DNA
iii. Uracil (U) – found only in RNA

b. Purine – 5 membered ring fused to a 6 membered ring

i. Adenine (A)
ii. Guanine (G)
NUCLEOTIDES CONT.
4. Function
a. Monomers for nucleic acids
b. Transfer chemical energy from one molecules to
another (ATP)
c. Are electron acceptors in enzyme controlled redox
reactions (NAD)

5. Phosphodiester linkages between phosphate of

one nucleotide and sugar of the next
DNA 1. Two nucleotide chains
STRUCTURE wound in a double
helix

2. Sugar-phosphate
backbones are on the
outside of the helix

3. Nitrogenous bases are

paired in the interior
of the helix and held
together by H bonds

4. A-T and C-G pairing

WHAT YOU NEED TO KNOW
ABOUT CH.5
THE PRINCIPLES OF POLYMERS
1. List the four major classes of macromolecules.

2. Distinguish between monomers and polymers.

3. Draw diagrams to illustrate condensation and

hydrolysis reactions.
CARBOHYDRATES SERVE AS FUEL AND BUILDING
MATERIAL

4. Distinguish between monosaccharides,

disaccharides, and polysaccharides.

5. Describe the formation of a glycosidic linkage.

6. Distinguish between the glycosidic linkages

found in starch and cellulose. Explain why the
difference is biologically important.

7. Describe the role of symbiosis in cellulose

digestion.
LIPIDS ARE A DIVERSE GROUP OF HYDROPHOBIC MOLECULES

8. Describe the building-block molecules, structure,

and biological importance of fats, phospholipids,
and steroids.

9. Identify an ester linkage and describe how it is

formed.

10. Distinguish between saturated and unsaturated

fats.

11. Name the principal energy storage molecules of

plants and animals.
PROTEINS HAVE MANY STRUCTURES AND MANY FUNCTIONS
12. Distinguish between a protein and a polypeptide.

13. Explain how a peptide bond forms between two amino acids.

14. List and describe the four major components of an amino acid. Explain how amino
acids may be grouped according to the physical and chemical properties of the R
group.

15. Explain what determines protein conformation and why it is important.

16. Explain how the primary structure of a protein is determined.

17. Name two types of secondary protein structure. Explain the role of hydrogen
bonds in maintaining secondary structure.

18. Explain how weak interactions and disulfide bridges contribute to tertiary protein
structure.

19. List four conditions under which proteins may be denatured.

NUCLEIC ACIDS STORE AND TRANSMIT HEREDITARY INFORMATION

20. List the major components of a nucleotide, and describe

how these monomers are linked to form a nucleic acid.

21. Distinguish between:

a. pyrimidine and purine
b. nucleotide and nucleoside
c. ribose and deoxyribose
d. 5’ end and 3’ end of a nucleotide

22. Briefly describe the three-dimensional structure of DNA.