1. Macromolecules of Life Proteins and Nucleic Acids
Chapter 5

2. You already know a lot about proteins!
You’ve been working with them in lab for the past 2-3 weeks!
Biuret – [protein]
Gel Electrophoresis
Enzymes

3. Protein Definition
Consists of one or more polypeptides folded, coiled, and twisted into a specific 3D shape
Proteios – “first place”
There are many different shapes of proteins depending on its FUNCTION
Enzymes
Cell signaling
Defense
Structural support
Transport
Receptors

4. Two similar terms Protein – already defined Polypeptide
– polymer made of repeating subunits of amino acids (monomer)
– usually refers to a long linear strand of amino acids that will then get folded into a 3D shape (protein)

5. Dehydration removes a water molecule, forming a new bond H2O
Fig. 5-2a HO 1 2 3 H HO H
Short polymer
Unlinked monomer
Dehydration removes a water
molecule, forming a new bond
H2O
Figure 5.2 The synthesis and breakdown of polymers HO 1 2 3 4 H
Longer polymer
(a)
Dehydration reaction in the synthesis of a polymer

6. HO 1 2 3 4 H H2O HO 1 2 3 H HO H (b) Hydrolysis adds a water
Fig. 5-2b HO 1 2 3 4 H
Hydrolysis adds a water
molecule, breaking a bond
H2O
Figure 5.2 The synthesis and breakdown of polymers HO 1 2 3 H HO H
(b)
Hydrolysis of a polymer

7. Fig. 5-UN1
 carbon
Amino
group
Carboxyl
group

8. Fig. 5-17 Figure 5.17 The 20 amino acids of proteins Nonpolar Glycine
(Gly or G)
Alanine
(Ala or A)
Valine
(Val or V)
Leucine
(Leu or L)
Isoleucine
(Ile or I)
Methionine
(Met or M)
Phenylalanine
(Phe or F)
Trypotphan
(Trp or W)
Proline
(Pro or P)
Polar
Serine
(Ser or S)
Threonine
(Thr or T)
Cysteine
(Cys or C)
Tyrosine
(Tyr or Y)
Asparagine
(Asn or N)
Glutamine
(Gln or Q)
Figure 5.17 The 20 amino acids of proteins
Electrically
charged
Acidic
Basic
Aspartic acid
(Asp or D)
Glutamic acid
(Glu or E)
Lysine
(Lys or K)
Arginine
(Arg or R)
Histidine
(His or H)

9. Nonpolar Glycine (Gly or G) Alanine (Ala or A) Valine (Val or V)
Fig. 5-17a
Nonpolar
Glycine
(Gly or G)
Alanine
(Ala or A)
Valine
(Val or V)
Leucine
(Leu or L)
Isoleucine
(Ile or I)
Figure 5.17 The 20 amino acids of proteins
Methionine
(Met or M)
Phenylalanine
(Phe or F)
Tryptophan
(Trp or W)
Proline
(Pro or P)

10. Polar Serine (Ser or S) Threonine (Thr or T) Cysteine (Cys or C)
Fig. 5-17b
Polar
Serine
(Ser or S)
Threonine
(Thr or T)
Cysteine
(Cys or C)
Tyrosine
(Tyr or Y)
Asparagine
(Asn or N)
Glutamine
(Gln or Q)
Figure 5.17 The 20 amino acids of proteins

11. Electrically charged Acidic Basic Aspartic acid (Asp or D)
Fig. 5-17c
Electrically
charged
Acidic
Basic
Figure 5.17 The 20 amino acids of proteins
Aspartic acid
(Asp or D)
Glutamic acid
(Glu or E)
Lysine
(Lys or K)
Arginine
(Arg or R)
Histidine
(His or H)

12. Amino end (N-terminus) Carboxyl end (C-terminus)
Fig. 5-18
Peptide
bond
(a)
Side chains
Peptide
bond
Figure 5.18 Making a polypeptide chain
Backbone
Amino end
(N-terminus)
Carboxyl end
(C-terminus)
(b)

13. Fig. 5-UN5

14. Fig. 5-21 Primary Structure Secondary Structure Tertiary Structure
Quaternary
Structure
 pleated sheet
+H3N
Amino end
Examples of
amino acid
subunits
 helix
Figure 5.21 Levels of protein structure—primary structure

15. Primary Structure Amino end Amino acid subunits +H3N 1 5 10 15 20 25
Fig. 5-21a
Primary Structure 1 5
+H3N
Amino end 10
Amino acid
subunits 15
Figure 5.21 Levels of protein structure—primary structure 20 25

16. Fig. 5-21b Figure 5.21 Levels of protein structure—primary structure
+H3N
Amino end 5 10 15
Amino acid
subunits 20 25 75 80
Figure 5.21 Levels of protein structure—primary structure 85 90 95
105
100
110
115
120
125
Carboxyl end

17. Secondary Structure  pleated sheet Examples of amino acid subunits
Fig. 5-21c
Secondary Structure
 pleated sheet
Examples of
amino acid
subunits
Figure 5.21 Levels of protein structure—secondary structure
 helix

18. Hydrophobic interactions and van der Waals interactions Polypeptide
Fig. 5-21f
Hydrophobic
interactions and
van der Waals
interactions
Polypeptide
backbone
Hydrogen
bond
Disulfide bridge
Figure 5.21 Levels of protein structure—tertiary and quaternary structures
Ionic bond

19. Tertiary Structure Quaternary Structure
Fig. 5-21e
Tertiary Structure
Quaternary Structure
Figure 5.21 Levels of protein structure—tertiary and quaternary structures

20. Polypeptide  Chains chain Iron Heme  Chains Hemoglobin Collagen
Fig. 5-21g
Polypeptide
chain
 Chains
Iron
Figure 5.21 Levels of protein structure—tertiary and quaternary structures
Heme
 Chains
Hemoglobin
Collagen

21. Normal hemoglobin Primary structure 1 2 3 4 5 6 7 Secondary
Fig. 5-22a
Normal hemoglobin
Primary
structure
Val
His
Leu
Thr
Pro
Glu
Glu 1 2 3 4 5 6 7
Secondary
and tertiary
structures
 subunit  
Quaternary
structure
Normal
hemoglobin
(top view)  
Figure 5.22 A single amino acid substitution in a protein causes sickle-cell disease
Function
Molecules do
not associate
with one
another; each
carries oxygen.

22. Sickle-cell hemoglobin Primary structure 1 2 3 4 5 6 7
Fig. 5-22b
Sickle-cell hemoglobin
Primary
structure
Val
His
Leu
Thr
Pro
Val
Glu 1 2 3 4 5 6 7
Exposed
hydrophobic
region
Secondary
and tertiary
structures
 subunit  
Quaternary
structure
Sickle-cell
hemoglobin  
Figure 5.22 A single amino acid substitution in a protein causes sickle-cell disease
Function
Molecules
interact with
one another and
crystallize into
a fiber; capacity
to carry oxygen
is greatly reduced.

23. 10 µm 10 µm Normal red blood cells are full of individual hemoglobin
Fig. 5-22c
10 µm
10 µm
Normal red blood
cells are full of
individual
hemoglobin
molecules, each
carrying oxygen.
Fibers of abnormal
hemoglobin deform
red blood cell into
sickle shape.
Figure 5.22 A single amino acid substitution in a protein causes sickle-cell disease

24. What Determines Protein Structure?
In addition to primary structure, physical and chemical conditions can affect structure
Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel
This loss of a protein’s native structure is called denaturation
A denatured protein is biologically inactive
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

25. Denaturation Normal protein Denatured protein Renaturation Fig. 5-23
Figure 5.23 Denaturation and renaturation of a protein
Normal protein
Denatured protein
Renaturation

26. The Roles of Nucleic Acids
There are two types of nucleic acids:
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis
Protein synthesis occurs in ribosomes
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

27. DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2
Fig
DNA 1
Synthesis of
mRNA in the
nucleus
mRNA
NUCLEUS
CYTOPLASM
mRNA 2
Movement of
mRNA into cytoplasm
via nuclear pore
Ribosome
Figure 5.26 DNA → RNA → protein 3
Synthesis
of protein
Amino
acids
Polypeptide

28. Nitrogenous base Phosphate group Sugar (pentose)
Fig. 5-27ab
5' end
5'C
3'C
Nucleoside
Nitrogenous
base
5'C
Phosphate
group
Figure 5.27 Components of nucleic acids
3'C
Sugar
(pentose)
5'C
3'C
(b) Nucleotide
3' end
(a) Polynucleotide, or nucleic acid

29. (c) Nucleoside components: nitrogenous bases
Fig. 5-27c-1
Nitrogenous bases
Pyrimidines
Cytosine (C)
Thymine (T, in DNA)
Uracil (U, in RNA)
Purines
Figure 5.27 Components of nucleic acids
Adenine (A)
Guanine (G)
(c) Nucleoside components: nitrogenous bases

30. (c) Nucleoside components: sugars
Fig. 5-27c-2
Sugars
Deoxyribose (in DNA)
Ribose (in RNA)
Figure 5.27 Components of nucleic acids
(c) Nucleoside components: sugars

31. The nitrogenous bases in DNA pair up and form hydrogen bonds:
Nucleotide Polymers
Adjacent nucleotides are joined by covalent bonds (phosphodiester linkage)
The nitrogenous bases in DNA pair up and form hydrogen bonds:
adenine (A) always with thymine (T)
guanine (G) always with cytosine (C)
Forms a double helix
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

32. 5' end 3' end Sugar-phosphate backbones Base pair (joined by
Fig. 5-28
5' end
3' end
Sugar-phosphate
backbones
Base pair (joined by
hydrogen bonding)
Old strands
Nucleotide
about to be
added to a
new strand
3' end
Figure 5.28 The DNA double helix and its replication
5' end
New
strands
5' end
3' end
5' end
3' end