Biological_Molecules it is about grade 11 biology.ppt

biological molecules

1. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
PowerPoint
®
Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Chapter 4
Carbon and the Molecular Diversity of Life
Chapter 5
The Structure and Function of Large
Biological Molecules
Topic 1 Biological Molecules

2. Learning Outcomes
•Distinguish among monosaccharides,
disaccharides and polysaccharides.
•Describe the formationand breakageof
glycosidic bond.
•Compare storage polysaccharides (starch and
glycogen) with structural polysaccharides
(cellulose), and relate these structures to their
functions in living organisms.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3. Learning Outcomes
•Analyze and distinguish among triglyceride,
phospholipids, fats, and steroids, and describe
the structural composition, characteristics, and
biological functions of each.
•Explain the meaning of the terms primary
structure, secondary structure, tertiary structure
and quaternary structure of proteins, and
describe the types of bonding which hold the
molecules in shape.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

4. Learning Outcomes
•Describe the general structure of an amino acid
and the formation and breakage of peptide
bond.
•Describe the components of a nucleotide and
identify their molecular structures.
•Describe the structure and composition of
nucleic acids (DNA and RNA), and discuss the
importance of base pairing and hydrogen
bonding.
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5. Rearrange these in the
correct order:

6. 1.
2.
3.
4.
5.
6.
7.
8.

7. Overview: Carbon: The Backbone of Life
•Although cells are 70–95% water, the rest
consists mostly of carbon-based compounds
•Carbonis unparalleled in its ability to form
large, complex, and diverse molecules
•Proteins, DNA, carbohydrates, and other
molecules that distinguish living matter are all
composed of carbon compounds
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8. Concept 4.1: Organic chemistry is the study of
carbon compounds
•Organic chemistryis the study of compounds
that contain carbon
•Organic compounds range from simple
molecules to colossal ones
•Most organic compounds contain hydrogen
atoms in addition to carbonatoms
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9. The Chemical Groups Most Important in the
Processes of Life
•Functional groupsare the components of
organic molecules that are most commonly
involved in chemical reactions
•The numberand arrangementof functional
groups give each molecule its unique
properties
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10. •The seven functional groups that are most
important in the chemistry of life:
–Hydroxyl group
–Carbonyl group
–Carboxyl group
–Amino group
–Sulfhydryl group
–Phosphate group
–Methyl group
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11. Fig. 2-16
 +
+

+
+
+
Water (H
2O)
Ammonia (NH
3)
Hydrogen bond
•A hydrogen bond forms
when a hydrogen atom
covalently bonded to
one electronegative
atom is also attracted to
another electronegative
atom
•In living cells, the
electronegative
partners are usually
oxygen or nitrogen
atoms

12. Overview: The Molecules of Life
•All living things are made up of four classes of
large biological molecules: carbohydrates,
lipids, proteins, and nucleic acids
•Within cells, small organic molecules are joined
together to form larger molecules
•Macromolecules are large molecules
composed of thousands of covalently
connected atoms
•Molecular structure and functionare
inseparable
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13. Concept 5.1: Macromolecules are polymers, built
from monomers
•A polymer is a long molecule consisting of
many similar building blocks
•These small building-block molecules are
called monomers
•Three of the four classes of life’s organic
molecules are polymers:
–Carbohydrates
–Proteins
–Nucleic acids
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14. The Synthesis and Breakdown of Polymers
•A condensation reaction or more specifically
a dehydration reaction occurs when two
monomers bond together through the loss of a
water molecule
•Enzymes are macromolecules that speed up
the dehydration process
•Polymers are disassembledto monomers by
hydrolysis, a reaction that is essentially the
reverse of the dehydration reaction
Animation: Polymers
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15. Fig. 5-2a
Dehydrationremoves a water
molecule, forming a new bond
Short polymer Unlinked monomer
Longer polymer
Dehydration reaction in the synthesis of a polymer
HO
HO
HO
H
2O
H
HH
4321
1 2 3
(a)

16. Fig. 5-2b
Hydrolysisadds a water
molecule, breaking a bond
Hydrolysis of a polymer
HO
HO HO
H
2O
H
H
H321
1 2 3 4
(b)

17. dehydration
synthesis
hydrolysis
Which diagram represents…
Is water removed or added?
Are polymers or monomers
formed?

18. The Diversity of Polymers
•Each cell has thousands of different kinds of
macromolecules
•Macromolecules vary among cells of an
organism, vary more within a species, and vary
even more between species
•An immense variety of polymers can be built
from a small set of monomers
23
HOH
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19. The Principle of Redox
•In oxidation, a substance loseselectrons, or is
oxidized
•In reduction, a substance gainselectrons, or is
reduced (the amount of positive charge is
reduced)
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Fig. 9-UN1
becomes oxidized
(loses electron)
becomes reduced
(gains electron)

20. •The electron donor is called the reducing agent
•The electron receptor is called the oxidizing
agent
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Fig. 9-UN2
becomes oxidized
becomes reduced
Self-study:

21. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
A B
Donates:
electron(s)/ H+
Receives:
electron(s)/ H+
Receives:
O
Donates:
O
Is called a:
A reducing agent
Is called:
An oxidizing agent
Has been:
Oxidized by B
Has been:
Reduced by A
If A reduces B…

22. CARBOHYDRATES

23. Concept 5.2: Carbohydrates serve as fuel and
building material
•Carbohydrates include sugarsand the
polymers of sugars
•The simplest carbohydrates are
monosaccharides, or single sugars
•Carbohydrate macromolecules are
polysaccharides, polymers composed of many
sugar building blocks
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24. Carbonyl
Ketonesif the carbonyl group
is within a carbon skeleton
Aldehydesif the carbonyl
group is at the end of the
carbon skeleton
The carbonyl group ( CO)
consists of a carbon atom
joined to an oxygen atom by a
double bond.
Acetone, the simplest ketone
Propanal, an aldehyde

25. Sugars
•Monosaccharides have molecular formulas
that are usually multiples of CH
2O
•Glucose (C
6H
12O
6) is the most common
monosaccharide
•Monosaccharides are classified by
–The location of the carbonyl group (as aldose
or ketose)
–The number of carbons in the carbon skeleton
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26. Fig. 5-3
Dihydroxyacetone
Ribulose
Fructose
Glyceraldehyde
Ribose
Glucose Galactose
Hexoses (C
6H
12O
6)Pentoses (C
5H
10O
5)Trioses (C
3H
6O
3)

27. Fig. 5-3a
Glyceraldehyde
Ribose
Glucose Galactose
Hexoses (C
6H
12O
6)Pentoses (C
5H
10O
5)Trioses (C
3H
6O
3)
What type of molecules are these?
How many carbons per molecule?

28. Fig. 5-3a
Glyceraldehyde
Ribose
Glucose Galactose
Hexoses (C
6H
12O
6)Pentoses (C
5H
10O
5)Trioses (C
3H
6O
3)
What type of molecules are these? Monosaccharide
How many carbons per molecule?

29. Fig. 5-3b
Dihydroxyacetone
Ribulose
Fructose
Hexoses (C
6H
12O
6)Pentoses (C
5H
10O
5)Trioses (C
3H
6O
3)
How are these molecules different from aldoses?

30. Fig. 5-3b
Dihydroxyacetone
Ribulose
Fructose
Hexoses (C
6H
12O
6)Pentoses (C
5H
10O
5)Trioses (C
3H
6O
3)
How are these molecules different from aldoses?
Location of the carbonyl group

31. •Though often drawn as linear skeletons, in
aqueous solutions many sugars form rings
•Monosaccharides serve as a majorfuel for
cells and as raw material for building molecules
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32. Fig. 5-4a
(a) Linear and ring forms
•Only sugars in solution which exist in linear form
are able to reduceother molecules because of
free aldehydegroup
•Circle the free aldehydegroups in diagram.

33. Fig. 5-4a
(a) Linear and ring forms
•Only sugars in solution which exist in linear form
are able to reduceother molecules because of
free aldehydegroup
•Circle the free aldehydegroups in diagram.

34. Fig. 5-4b
(b) Abbreviated ring structure

35. •A disaccharideis formed when a dehydration
reaction joins two monosaccharides
•This covalent bond is called a glycosidic
linkage
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36. •Which is a
–Monosaccharide?
–Disaccharide?
•What is the name of the bond formed between
monomers?
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37. Fig. 5-5
(b) Dehydration reaction in the synthesis of sucrose
Glucose Fructose Sucrose
MaltoseGlucoseGlucose
(a) Dehydration reaction in the synthesis of maltose
1–4
glycosidic
linkage
1–2
glycosidic
linkage

38. Why is sucrose non-reducing?
•Is there any free
aldehyde or keto
group in the
sucrose diagram?
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39. Why is maltose reducing?
•Is there any free
aldehyde or keto
group in the
maltose diagram?
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40. Polysaccharides
•Polysaccharides, the polymers of sugars,
have storageand structuralroles
•The structure and function of a polysaccharide
are determined by its sugar monomers and the
positions of glycosidic linkages
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41. Fig. 5-7a
(a) and glucose ring structures
Glucose Glucose

42. What is the difference between and glucose ring
structures?
•When the hydroxyl (-OH) group attached to
carbon 1 is on the same side of the plane of
the ring as the hydroxymethyl (-CH
2OH) group,
the glucose is designated glucose
•When (-OH) group is on the other side of the
plane as the (-CH
2OH) group, the glucose is
designated glucose
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43. •Polymers with glucose are helical
•Polymers with glucose are straight
•In straight structures, H atoms on one
strand can bond with OH groups on other
strands
•Parallel cellulose molecules held together
this way are grouped into microfibrils, which
form strong building materials for plants
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44. Storage Polysaccharides (alpha glucose)
•Starch, a storage polysaccharide of plants,
consists entirely of glucose monomers
•Plants store surplus starch as granules within
chloroplasts and other plastids
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45. •Glycogen is a storage polysaccharide in
animals
•Humans and other vertebrates store glycogen
mainly in liver and muscle cells
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46. Fig. 5-6
(b) Glycogen: an animal polysaccharide
Starch
GlycogenAmylose
Chloroplast
(a) Starch: a plant polysaccharide
Amylopectin
MitochondriaGlycogen granules
0.5 µm
1 µm
•What shapes do these polymers have?

47. Raven
•What type of linkage branching do starch &
glycogen share in common?
•Which is more branched?

48. Structural Polysaccharides (beta glucose)
•The polysaccharide cellulose is a major
component of the tough wall of plant cells
•Like starch, cellulose is a polymer of glucose,
but the glycosidic linkages differ
•The difference is based on two ring forms for
glucose: alpha () and beta ()
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49. Fig. 5-8
bGlucose
monomer
Cellulose
molecules
Microfibril
Cellulose
microfibrils
in a plant
cell wall
0.5 µm
10 µm
Cell walls
•What shape does cellulose have?

50. Fig. 5-7bc
(b) Starch: 1–4 linkage of αglucose monomers
(c) Cellulose: 1–4 linkage of βglucose monomers
•Why are the glycosidic bonds called: ? 1, 4?
•Why are the glycosidic bonds called: β? 1, 4?

51. •Enzymesthat digest starch by hydrolyzing 
linkages can’t hydrolyze linkages in cellulose
•Cellulosein human food passes through the
digestive tract as insoluble fiber
•Some microbes use enzymes to digest
cellulose
•Many herbivores, from cowsto termites, have
symbiotic relationships with these microbes
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52. Fig. 5-9

53. •Chitin, another structural polysaccharide, is
found in the exoskeleton of arthropods
•Chitin also provides structural supportfor the
cell walls of many fungi
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54. Fig. 5-10
The structure
of the chitin
monomer.
(a) (b) (c)Chitin forms the
exoskeleton of
arthropods.
Chitin is used to make
a strong and flexible
surgical thread.

55. LIPIDS

56. Hydrocarbons
•Hydrocarbonsare organic molecules
consisting of only carbon and hydrogen
•Many organic molecules, such as fats, have
hydrocarbon components
•Hydrocarbons can undergo reactions that
release a large amount of energy
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57. Fig. 4-6
(a) Mammalian adipose cells (b) A fat molecule
Fat droplets (stained red)
100 µm
(Chp 4)
Exam self-study:

58. Concept 5.3: Lipids are a diverse group of
hydrophobic molecules
•Lipids are the one class of large biological
molecules that do not form polymers
•The unifying feature of lipids is having little or
no affinity for water
•Lipids are hydrophobicbecausethey consist
mostly of hydrocarbons, which form nonpolar
covalent bonds
•The most biologically important lipids are fats,
phospholipids, and steroids
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59. Fats
•Fats are constructed from two types of smaller
molecules: glyceroland fatty acids
•Glycerol is a three-carbon alcohol with a
hydroxyl group attached to each carbon
•A fatty acid consists of a carboxyl group
attached to a long carbon skeleton
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60. Fig. 5-11a
Fatty acid
(palmitic acid)
Glycerol
•What is the type of reaction above?

61. Fig. 5-11b
•What is this linkage?
•Name this fat molecule.

62. •Fats separate from water because water
molecules form hydrogen bondswith each
other and exclude the fats
•In a fat, three fatty acids are joined to glycerol
by an ester linkage, creating a triacylglycerol,
or triglyceride
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63. •Fatty acids vary in length(number of carbons)
and in the number and locations of double
bonds
•Saturated fatty acids have the maximum
number of hydrogen atoms possible and no
double bonds
•Unsaturated fatty acids have one or more
double bonds
Animation: Fats
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64. Fig. 5-12a
Structural
formula of a
saturated fat
molecule
Stearic acid
•Is this fat saturated or unsaturated?

65. Fig. 5-12b
Structural formula
of an unsaturated
fat molecule
Oleicacid
cisdouble
bond causes
bending
•Is this fat saturated or
unsaturated?

66. •Fats made from saturated fatty acids are called
saturated fats, and are solid at room
temperature
•Most animal fats are saturated
•Fats made from unsaturated fatty acids are
called unsaturated fats or oils, and are liquid at
room temperature
•Plant fats and fish fats are usually unsaturated
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67. •A diet rich in saturated fats may contribute to
cardiovascular disease through plaque deposits
•Hydrogenationis the process of converting
unsaturated fats to saturated fats by adding
hydrogen
•Hydrogenating vegetable oils also creates
unsaturated fats with transdouble bonds
•These trans fats may contribute more than
saturated fats to cardiovascular disease
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68. •Why is glycerol, on its own, hydrophilic?
•If glycerol is hydrophilic, what causes fat to be
hydrophobic?

69. •The major function of fats is energy storage
•Humans and other mammals store their fat in
adipose cells
•Adipose tissue also cushions vital organs and
insulates the body
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70. Phospholipids
•In a phospholipid, two fatty acids and a
phosphate group are attached to glycerol
•The two fatty acid tails are hydrophobic, but the
phosphate group and its attachments form a
hydrophilichead
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71. Fig. 5-13ab
(b)Space-filling model(a)Structural formula
Fatty acids
Choline
Phosphate
Glycerol
Hydrophobic tails
Hydrophilic head

72. •When phospholipids are added to water, they
self-assemble into a bilayer, with the
hydrophobictails pointing toward the interior
•The structure of phospholipids results in a
bilayer arrangement found in cell membranes
•Phospholipids are the major component of all
cell membranes
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73. Fig. 5-14
Hydrophilic
head
Hydrophobic
tail
WATER
WATER

74. Steroids
•Steroids are lipids characterized by a carbon
skeleton consisting of four fused rings
•Cholesterol, an important steroid, is a
componentin animal cell membranes
•Although cholesterol is essential in animals,
high levels in the blood may contribute to
cardiovascular disease
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75. Fig. 5-15
progesterone
cholesterol
testosterone
estrogen

76. PROTEINS

77. Concept 5.4: Proteins have many structures,
resulting in a wide range of functions
•Proteinsaccount for more than 50% of the dry
massof most cells
•Protein functions include structural support,
storage, transport, cellular communications,
movement, and defense against foreign
substances
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78. Table 5-1

79. •Enzymesare a type of protein that acts as a
catalystto speed up chemical reactions
•Enzymes can perform their functions
repeatedly, functioning as workhorses that
carry out the processes of life
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80. Fig. 5-16
Enzyme
(sucrase)
Substrate
(sucrose)
Fructose
Glucose
OH
HO
H
2O

81. Polypeptides
•Polypeptides are polymers built from the
same set of 20 amino acids
•A protein consists of one or more polypeptides
•What shape do most proteins have? Globular
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82. Amino Acid Monomers
•Amino acids are organic molecules with
carboxyl and amino groups
•Amino acids differ in their properties due to
differing side chains, called R groups
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83. Fig. 5-UN1
Amino
group
Carboxyl
group
αcarbon

84. Fig. 4-10c: Is this functional group soluble in water or lipids?
STRUCTURE
EXAMPLE
NAME OF
COMPOUND
FUNCTIONAL
PROPERTIES
Carboxyl
Acetic acid, which gives vinegar
its sour taste
Carboxylic acids, or organic
acids
Has acidic properties
because the covalent bond
between oxygen and hydrogen
is so polar; for example,
Found in cells in the ionized
form with a charge of 1–and
called a carboxylate ion (here,
specifically, the acetate ion).
Acetic acid Acetate ion

85. Fig. 4-10d : Is this functional group soluble in water or lipids?
STRUCTURE
EXAMPLE
NAME OF
COMPOUND
FUNCTIONAL
PROPERTIES
Amino
Because it also has a
carboxyl group, glycine
is both an amine and
a carboxylic acid;
compounds with both
groups are called
amino acids.
Amines
Acts as a base; can
pick up an H
+
from
the surrounding
solution (water, in
living organisms).
Ionized, with a
charge of 1+, under
cellular conditions.
(ionized)(nonionized)
Glycine

86. Fig. 4-10e :
STRUCTURE
EXAMPLE
NAME OF
COMPOUND
FUNCTIONAL
PROPERTIES
Sulfhydryl
(may be
written HS—)
Cysteine
Cysteine is an important
sulfur-containing amino
acid.
Thiols
Two sulfhydryl groups
can react, forming a
covalent bond. This
“cross-linking” helps
stabilize protein
structure.
Cross-linking of
cysteines in hair
proteins maintains the
curliness or straightness
of hair. Straight hair can
be “permanently” curled
by shaping it around
curlers, then breaking
and re-forming the
cross-linking bonds.

87. Frederick Sanger (born 1918)
Englishbiochemistand a two-timeNobel laureate in
chemistry
1958 -structure of proteins, especially that of insulin
1980 -determination of base sequences in nucleic acids

88. Fig. 5-17a
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)
Tryptophan
(Trp or W)
Proline
(Pro or P)

89. Fig. 5-17b
Polar
Asparagine
(Asn or N)
Glutamine
(Gln or Q)
Serine
(Ser or S)
Threonine
(Thr or T)
Cysteine
(Cys or C)
Tyrosine
(Tyr or Y)

90. Fig. 5-17c
Acidic
Arginine
(Arg or R)
Histidine
(His or H)
Aspartic acid
(Asp or D)
Glutamic acid
(Glu or E)
Lysine
(Lys or K)
Basic
Electrically
charged

91. Amino Acid Polymers
•Amino acids are linked by peptide bonds
•A polypeptide is a polymer of amino acids
•Polypeptides range in length from a few to
more than a thousand monomers
•Each polypeptide has a unique linear sequence
of amino acids
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92. Peptide
bond
Fig. 5-18
Amino end
(N-terminus)
Peptide
bond
Side chains
Backbone
Carboxyl end
(C-terminus)
(a)
(b)

93. W
Fig. 5-18
Amino end
(N-terminus)
W
Side chains
Backbone
Carboxyl end
(C-terminus)
(a)
(b)
•What type of
reaction is this?
•What is the name
of bond W?
•Which is an
example of a
‘dipeptide’ &
‘tripeptide’?

94. Protein Structure and Function
•A functional protein consists of one or more
polypeptidestwisted, folded, and coiled into a
unique shape
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•The sequence of amino acids determines a
protein’s three-dimensional structure
•A protein’s structure determines its function

95. Fig. 5-19
A ribbon model of lysozyme(a) (b)A space-filling model of lysozyme
Groove
Groove

96. Four Levels of Protein Structure
•Primary structure
•Secondary structure
•Tertiary structure
•Quaternary structure
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97. Four Levels of Protein Structure
•The primarystructure of a protein is its unique
sequence of amino acids
•Secondarystructure, found in most proteins,
consists of coils and folds in the polypeptide
chain
•Tertiarystructure is determined by interactions
among various side chains (R groups)
•Quaternarystructure results when a protein
consists of multiple polypeptide chains
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98. •The primary structureof a protein is its unique
sequence of amino acids
•Primary structure, the sequence of amino
acids in a protein, is like the order of letters in a
long word
•Primary structure is determined by inherited
genetic information
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99. Fig. 5-21a
Amino acid
subunits
+
H
3
N
Amino end
25
20
15
10
5
1
Primary Structure

100. •What bondsare involved in primary structure?
•Which parts of two amino acids are involved per
bond?

101. •The coils and folds of secondary structure
result from hydrogen bonds between repeating
constituents of the polypeptide backbone
•Typical secondary structures are a coil called
an helix and a foldedstructure called a 
pleated sheet
Animation: Secondary Protein Structure
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102. Fig. 5-21c
Secondary Structure
βpleated sheet
Examples of
amino acid
subunits
αhelix
•What bonds are
responsible for
producing such
shapes?

103. Fig. 5-21d
Abdominal glands of the
spider secrete silk fibers
made of a structural protein
containing pleated sheets.
The radiating strands, made
of dry silk fibers, maintain
the shape of the web.
The spiral strands (capture
strands) are elastic, stretching
in response to wind, rain,
and the touch of insects.

104. •Tertiary structure is determined by
interactions between R groups, rather than
interactions between backbone constituents
•These interactions between R groups include
hydrogen bonds, ionic bonds, hydrophobic
interactions, and van der Waals interactions
•Strong covalent bonds called disulfide
bridges may reinforce the protein’s structure
Animation: Tertiary Protein Structure
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105. Fig. 5-21f
Polypeptide
backbone
Hydrophobic
interactions and
van der Waals
interactions
Disulfide bridge
Ionic bond
Hydrogen
bond

106. Fig. 5-21e
Tertiary StructureQuaternary Structure

107. •What type of bonds or interactions produce
tertiary structure?
•Which component of an amino acid contribute
to those bonds or interactions that produce
tertiary structure?
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108. •Quaternary structure results when two or
more polypeptide chainsform one
macromolecule
•Collagenis a fibrous protein consisting of
three polypeptides coiled like a rope
•Hemoglobinis a globular protein consisting of
four polypeptides: two alpha and two beta
chains
Animation: Quaternary Protein Structure
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109. Fig. 5-21g
Polypeptide
chain
Chains
Heme
Iron
αChains
Collagen
Hemoglobin
Which levels of protein structure are represented above?

110. •How many polypeptides are involved?
•What type of bonds give rise to Quaternary
Structure?
•Are these intra-or inter-polypeptide bonds?
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111. Fig. 5-21
Primary
Structure
Secondary
Structure
Tertiary
Structure
pleated sheet
Examples of
amino acid
subunits
+
H
3N
Amino end
helix
Quaternary
Structure

112. Sickle-Cell Disease: A Change in
Primary Structure
•A slight change in primary structure can affect
a protein’s structureand ability to function
•Sickle-cell disease, an inherited blood
disorder, results from a single amino acid
substitutionin the protein hemoglobin
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113. Fig. 5-22a
Primary
structure
Secondary
and tertiary
structures
Function
Quaternary
structure
Molecules do
not associate
with one
another; each
carries oxygen.
Normal
hemoglobin
(top view)
subunit
Normal hemoglobin
7654321
β
α
α
β
GluValHisLeuThrPro Glu

114. Fig. 5-22b
Primary
structure
Secondary
and tertiary
structures
Function
Quaternary
structure
Molecules
interact with
one another and
crystallize into
a fiber; capacity
to carry oxygen
is greatly reduced.
Sickle-cell
hemoglobin
subunit
Sickle-cell hemoglobin
7654321
β
α
α
β
ValValHisLeuThrPro Glu
Exposed
hydrophobic
region

115. Fig. 5-22c
Normal red blood
cells are full of
individual
hemoglobin
molecules, each
carrying oxygen.
Fibers of abnormal
hemoglobin deform
red blood cell into
sickle shape.
10 µm 10 µm

116. What Determines Protein Structure?
•In addition to primary structure, physical and
chemical conditionscan 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
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117. Fig. 5-23
Normal protein Denatured protein
Denaturation
Renaturation

118. Although polypeptide and protein are often used
interchangeably…
Terms Match terms (left) with definitions (below)
Protein?
Polypeptide?
Peptide?
1.two or more amino acids joined
2.linear polymer composed of multiple
amino acids
3.not-yet functional product
4.large polypeptides.
5.a functional product after undergoing
subsequent chemical modification
(discussed later).

119. Concept 5.5: Nucleic acids store and transmit
hereditary information
•If the primary structure of polypeptide
determines a protein’s shape, what determines
the primary structure?
•The amino acid sequence of a polypeptide is
programmed by a unit of inheritance called a
gene
•Genes are made of DNA, a nucleic acid
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120. Extra information
•Each chromosomecontain one long DNA
molecule, carrying few hundreds genes.
•Coded in the structure of DNA is the
information that program all the cell’s activities.
•DNA determines the primary structure of
proteins.
•mRNA convey the genetic information for
building protein from nucleus (DNA) to
cytoplasm(ribosome, site of protein synthesis)
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121. The Roles of Nucleic Acids
•There are two types of nucleic acids:
–Deoxyribonucleic acid (DNA)
–Ribonucleic acid (RNA)
•DNA provides directions for its own replication
•DNA directs synthesisof messenger RNA
(mRNA) and, through mRNA, controls protein
synthesis
•Protein synthesis occurs in ribosomes
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122. The Structure of Nucleic Acids
•Nucleic acids are polymers called
polynucleotides
•Each polynucleotide is made of monomers
called nucleotides
•Each nucleotide consists of a nitrogenous
base, a pentose sugar, and a phosphate group
•The portion of a nucleotide without the
phosphate group is called a nucleoside
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123. Fig. 5-27ab
5'end
5'C
3'C
5'C
3'C
3'end
(a) Polynucleotide, or nucleic acid
(b) Nucleotide
Nucleoside
Nitrogenous
base
3'C
5'C
Phosphate
group
Sugar
(pentose)

124. Fig. 5-27
5end
Nucleoside
Nitrogenous
base
Phosphate
group
Sugar
(pentose)
(b) Nucleotide
(a) Polynucleotide, or nucleic acid
3end
3C
3C
5C
5C
Nitrogenous bases
Pyrimidines
Cytosine (C)Thymine (T, in DNA)Uracil (U, in RNA)
Purines
Adenine (A) Guanine (G)
Sugars
Deoxyribose (in DNA) Ribose (in RNA)
(c) Nucleoside components: sugars

125. Nucleotide Monomers
•Nucleoside = nitrogenous base + sugar
•There are two families of nitrogenous bases:
–Pyrimidines (cytosine, thymine, and uracil)
have a single six-membered ring
–Purines (adenine and guanine) have a six-
membered ring fusedto a five-membered ring
•In DNA, the sugar is deoxyribose; in RNA, the
sugar is ribose
•Nucleotide = nucleoside + phosphate group
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126. Fig. 5-27c-1
(c) Nucleoside components: nitrogenous bases
Purines
Guanine (G)Adenine (A)
Cytosine (C)Thymine (T, in DNA)Uracil (U, in RNA)
Nitrogenous bases
Pyrimidines

127. Fig. 5-27c-2
Ribose (in RNA)Deoxyribose (in DNA)
Sugars
(c) Nucleoside components: sugars

128. Nucleotide Polymers
•Nucleotide polymers are linked together to build
a polynucleotide
•Adjacent nucleotides are joined by covalent
bonds–phosphodiester bondthat form
between the –OH group on the 3carbon of one
nucleotide and the phosphate on the 5carbon
on the next
•These links create a backbone of sugar-
phosphateunits with nitrogenous bases as
appendages
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

129. Fig. 5-27ab
5'end
5'C
3'C
5'C
3'C
3'end
(a) Polynucleotide, or nucleic acid
(b) Nucleotide
Nucleoside
Nitrogenous
base
3'C
5'C
Phosphate
group
Sugar
(pentose)
•Circle a nucleotide in diagram (a)
•Name the bond between
nucleotides.

130. Fig. 5-27ab
5'end
5'C
3'C
5'C
3'C
3'end
(a) Polynucleotide, or nucleic acid
(b) Nucleotide
Nucleoside
Nitrogenous
base
3'C
5'C
Phosphate
group
Sugar
(pentose)
•At which carbon of pentose is
•Phosphate attached?
•Base attached?

131. •Which bases pair
up?
•What bond is
formed in base-
pairing?

132. The DNA Double Helix
•A DNA molecule has two polynucleotides spiraling
around an imaginary axis, forming a double helix
•In the DNA double helix, the two backbones run in
opposite 5→ 3directions from each other, an
arrangement referred to as antiparallel
•One DNA molecule includes many genes
•The nitrogenous bases in DNA pair up and form
hydrogen bonds: adenine (A) always with thymine
(T), and guanine (G) always with cytosine (C)
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133. Fig. 5-28
Sugar-phosphate
backbones
3' end
3' end
3' end
3' end
5' end
5' end
5' end
5' end
Base pair (joined by
hydrogen bonding)
Old strands
New
strands
Nucleotide
about to be
added to a
new strand

134. 1953

135. Fig. 5-UN2a

136. Fig. 5-UN2b