Transcript video slide - Human Anatomy

Chapter 3
Carbon and the Molecular Diversity
of Life
http://youtu.be/PYH63o10iTE
1
Carbon Chemistry
• Carbon is the Backbone of Biological
Molecules (macromolecules)
• All living organisms Are made up of chemicals
based mostly on the element carbon
Video
Figure 4.1
2
There are 4 types of Biological
Macromolecules
Carbohydrates like sugar, starch, chiton, cellulose,
potatoes and candy!
Lipids like fat, butter, cream and olive oil (all other oils
as well including motor oil)
Proteins like steak, collagen (jello), hair and the
machinery that runs your cellular metabolism
Nucleic Acids – these are DNA and RNA which are
responsible for storing information about how to build
proteins
3
Carbon Chemistry
• Organic chemistry is the study of carbon
compounds
• Carbon atoms can form diverse molecules by
bonding to four other atoms or molecules
• Carbon compounds range from simple
molecules to complex ones
• Carbon has four valence electrons and may
form single, double, triple, or quadruple
bonds
4
• The bonding versatility of carbon allows
it to form many diverse molecules,
including carbon skeletons
Name and
Comments
(a) Methane
Molecular Structural
Formula
Formula
Ball-andStick
Model
SpaceFilling
Model
H
CH4
H C
H
H
(b) Ethane
C2H
6
(c) Ethene
Figure 4.3 A-C (ethylene)
C2H4
H H
H C C H
H H
H
H
C C
H
H
5
• The electron configuration of carbon gives it
covalent compatibility with many different
elements
Hydrogen
Oxygen
Nitrogen
Carbon
(valence = 1)
(valence = 2)
(valence = 3)
(valence = 4)
H
O
N
C
Figure 4.4
6
• Carbon may bond to itself forming carbon chains
• Carbon chains form the skeletons of most organic
molecules
• Carbon chains vary in length and shape
• The following diagrams show the atoms and their
bonds
H H H H
H C C C C
H H H H
Butane
(b) Branching
(c) Double bonds
(d) Rings
Figure 4.5 A-D
H H H
H H
H C C H
H H
Ethane
(a) Length
H
H
H
H
H
H H H H
H C C C C
H H
1-Butene
H
H
H
C
C
C H
C
C H
H
C
Cyclohexane
H C C C H
H H H
Propane
H
H C H
H
H
H C C C H
H H H
isobutane
H
H H H H
H C C C C H
H
H
2-Butene
H
H
C C H
C
C
C
Benzene
7
Notice that the way the methane is drawn bears no resemblance to
the actual shape of the molecule. Methane isn't flat with 90° bond
angles. This mismatch between what you draw and what the
molecule actually looks like can lead to problems if you aren't
careful.
8
Hydrocarbons
• Hydrocarbons are molecules consisting of only
carbon and hydrogen
• Hydrocarbons Are found within many of a cell’s organic
molecules
Fat droplets (stained red)
Figure 4.6 A, B
(a) A fat molecule
100 µm
(b) Mammalian adipose cells
9
Functional Groups
• Functional groups are
the parts of
molecules involved in
chemical reactions
• They Are the
chemically reactive
groups of atoms
within an organic
molecule
• Give organic
molecules distinctive
chemical properties
Estradiol
HO
Female lion
OH
CH3
CH3
O
Figure 4.9
OH
CH3
Testosterone
Male lion
10
Macromolecules
– Are large molecules composed of smaller molecules
– Are complex in their structures
Figure 5.1
11
Macromolecules
•Most macromolecules are polymers, built from monomers
•A monomer is a single unit of a polymer like legos!
• Four classes of life’s organic
molecules are polymers
– Carbohydrates (include sugars, starches etc)
– Proteins
– Nucleic acids
– Lipids (fats)
12
• A polymer
– Is a long molecule consisting of many similar
building blocks called monomers
– Specific monomers make up each
macromolecule
– E.g. amino acids are the monomers for
proteins
13
The Synthesis and Breakdown of
Polymers
• Monomers form larger molecules by condensation reactions called
dehydration synthesis
• DRAW THIS AND CHECK WITH YOUR GROUP THAT IT IS
RIGHT!
HO
1
2
3
H
Unlinked monomer
Short polymer
Dehydration removes a water
molecule, forming a new bond
HO
1
2
H
HO
3
H 2O
4
H
Longer polymer
Figure 5.2A (a) Dehydration reaction in the synthesis of a polymer
14
The Synthesis and Breakdown of
Polymers
• Polymers can disassemble by
– Hydrolysis (addition of water molecules)
– DRAW THIS AND COMPARE IT WITH YOUR GROUP TO
MAKE SURE IT’S RIGHT!
HO
1
2
3
4
Hydrolysis adds a water
molecule, breaking a bond
HO
1
2
3
H
H
H 2O
HO
H
Figure 5.2B (b) Hydrolysis of a polymer
15
• Although organisms share the same
limited number of monomer types,
each organism is unique based on the
arrangement of monomers into
polymers
• An immense variety of polymers can be
built from a small set of monomers
16
Carbohydrates
• Serve as fuel and building material
• Include both sugars and their polymers
(starch, cellulose, etc.)
• Carbohydrates are either:
• Monosaccharides – a single monomer
Disaccharides - two monomers
• Polysaccharides – three or more monos
17
Sugars
• Monosaccharides
– Are the simplest sugars
– Can be used for fuel
– Can be converted into other organic
molecules
– Can be combined into polymers
18
• Examples of monosaccharides
Triose sugars Pentose sugars
(C3H6O3)
(C5H10O5)
Aldoses
H
C
O
H
O
C
H
O
C
H
C
OH
H
C
OH
H
C
OH
H
C
OH
H
C
OH
HO
C
H
C
OH
H
H
C
OH
H
Glyceraldehyde
H
H
H
H
C
OH
H
HO
C
H
C
OH
HO
C
H
H
C
OH
H
C
OH
H
C
OH
H
C
OH
H
H
Glucose
Galactose
H
C OH
C
O
H
C OH
C
O
O
C OH
H
C OH
HO
H
H
C OH
H
C OH
Dihydroxyacetone H C OH
H
C OH
H
C OH
H
H
O
H
H
C OH
C
Ketoses
H
C
Ribose
Figure 5.3
Hexose sugars
(C6H12O6)
Ribulose
C H
H
Fructose
19
• Monosaccharides
– May be linear
– Can form rings
H
H
HO
H
H
H
O
1C
2
6CH
C
OH
C
H
C
OH
3
4
5
C
6
C
OH
OH
2OH
5C
H
4C
OH 3
H
OH
C
H
6CH
O
H
2C
OH
H
1C
H
O
H
4C
OH
2OH
5C
H
OH
3C
H
CH2OH
O
H
H
1C
2C
OH
OH
6
H
5
4
HO
H
OH
3
H
O
H
1
2
OH
OH
H
Figure 5.4 (a) Linear and ring forms. Chemical equilibrium between the linear and ring
structures greatly favors the formation of rings. To form the glucose ring,
carbon 1 bonds to the oxygen attached to carbon 5.
20
• Disaccharides
– Consist of two monosaccharides
– Are joined by a glycosidic linkage
– a glycosidic bond is a type of covalent
bond that joins a carbohydrate (sugar)
molecule to another group, which may or may
not be another carbohydrate.
21
(a) Dehydration reaction
in the synthesis of
maltose. The bonding
of two glucose units
H
forms maltose. The
glycosidic link joins
the number 1 carbon
of one glucose to the HO
number 4 carbon of
the second glucose.
Joining the glucose
monomers in a
different way would
result in a different
disaccharide.
H
(b) Dehydration reaction
H
in the synthesis of
O
sucrose. Sucrose is
a disaccharide formed
from glucose and fructose.
Notice that fructose,
though a hexose like
glucose, forms a
five-sided ring.
CH2OH
CH2OH
O
H
OH H
H
H
H
OH
HO
H
OH
H 2O
H
O
H
Glucose
CH2OH
H
O
H
HO
H 2O
O
H
H
OHOH
H
HO
H
O
H
H
OH
O
H
CH2OH
H
1–4
1 glycosidic
linkage
HO
OH
H
Fructose
H
O
H
H
O
H
H
OH
OH
Maltose
H
H
4
O
CH2OH
O
H
OH
Glucose
Glucose
CH2O
H
O
H
O
H
H
H
OH
CH2OH
CH2OH
H
HO
H
O
H
O
H
OH
H
1–2
H
glycosidic
1
linkage
O
CH2OH
O
2
H HO
H
CH2OH
OH H
Sucrose
Figure 5.5
22
Polysaccharides
• Polysaccharides (poly = many)
– Are polymers of sugars
– Serve many roles in organisms
23
Storage Polysaccharides
• Starch
Chloroplast
Starch
– Is a polymer consisting
entirely of glucose monomers
– Is the major storage form of
glucose in plants
1 m
Amylose
Amylopectin
Figure 5.6(a) Starch: a plant polysaccharide
24
• Glycogen
– Consists of glucose monomers
– Is the major storage form of glucose in animals
Mitochondria Giycogen
granules
0.5 m
Glycogen
Figure 5.6(b) Glycogen: an animal polysaccharide
25
•
Structural
Polysaccharides
Cellulose
– Is a polymer of glucose
26
– Has different glycosidic linkages than starch
H
4
H
O
CH2O
H
O
HO
H H
H
O
H
H
H
O
H
 glucose
O
C
H
H
O
H
C
H
C
H
C
O
H
H
O
H
O
H
O
H
C
C
CH2O
H
O
H
O
H
H
H
4
H
O
O
H
H
O
H
1
H
 glucose
(a)  and  glucose ring structures
H
O
CH2O
H
O
O
H
1
O
4
CH2O
H
O
O
H
1
O
4
CH2O
H
O
O
H
1
O
4
CH2O
H
O
O
H
H
O
Figure 5.7 A–C
O
H
1
O
4
O
H
O
CH2O
H
O
O
H
O
O
H
O
O
O
H
H
H
(b) Starch: 1– 4 linkage of  glucose monomers
CH2O
H
O
O
H
1
O
H
O
O
H
O
O
CH2O
CH2O
O
O
H
H
H
H
(c) Cellulose: 1– 4 linkage of  glucose monomers
O
H
27
The formulae for both glucose and fructose are
identical. How do they differ?
28
– Is a major component of the tough walls that enclose plant
cells
Cell walls
Cellulose microfibrils
in a plant cell wall
Microfibril
About 80 cellulose
molecules associate
to form a microfibril, the
main architectural unit
of the plant cell wall.
0.5 m
Plant cells
Parallel cellulose molecules are
held together by hydrogen
bonds between hydroxyl
groups attached to carbon
atoms 3 and 6.
Figure 5.8
OH CH2OH
OH
CH2OH
O O
O O
OH
OH
OH
OH
O
O O
O O
O CH OH
OH
CH2OH
2
H
CH2OH
OH CH2OH
OH
O O
O O
OH
OH
OH
OH
O
O O
O O
O CH OH
OH
CH
2
2OH
H
CH2OH
OH
OH CH2OH
O O
O O
OH
OH
OH O
O OH
O O
O
O CH OH
OH CH2OH
2
H
 Glucose
monomer
Cellulose
molecules
A cellulose molecule
is an unbranched 
glucose polymer.
29
• Cellulose is difficult to digest
– Cows have microbes in their stomachs to facilitate this
process
Figure 5.9
30
• Chitin, another important structural polysaccharide
– Is found in the exoskeleton of arthropods
– Can be used as surgical thread
CH2O
H
O OH
H
H
OH H
OH
H
H
NH
C
O
CH3
(b) Chitin forms the exoskeleton
(a) The structure of the
of arthropods. This cicada
chitin monomer.
is molting, shedding its old
exoskeleton and emerging
Figure 5.10 A–C
in adult form.
(c) Chitin is used to make a
strong and flexible surgical
thread that decomposes after
the wound or incision heals.
31
Lipids
• Lipids are a diverse group of
hydrophobic molecules
• Lipids
– Are the one class of large biological
molecules that do not consist of polymers
– Share the common trait of being
hydrophobic
32
Fats
– Are constructed from two types of smaller molecules, a single
glycerol and usually three fatty acids
– Vary in the length and number and locations of double bonds they
contain
33
Fats
– Are constructed from two types of smaller molecules, a single
glycerol and usually three fatty acids
– Vary in the length and number and locations of double bonds they
contain
34
Fats
• Are constructed from two types of smaller molecules, a single
glycerol and usually three fatty acids
35
Fats
• Vary in the length and number and locations of double bonds
they contain
36
• Saturated fatty acids
– Have the maximum number of hydrogen atoms
possible
– Have no double bonds
Stearic acid
(a) Saturated fat and fatty acid
Figure 5.12
37
• Unsaturated fatty acids
– Have one or more double bonds
Oleic acid
Figure 5.12 (b) Unsaturated fat and fatty acid
cis double bond
causes bending
38
• Phospholipids
– Have only two fatty acids
– Have a phosphate group instead of a third fatty acid
39
• Phospholipid structure
– Consists of a hydrophilic “head” and hydrophobic
“tails”
CH2
CH2
O
O
P
O–
+
N(CH3)3
Choline
Phosphate
O
CH2
CH
O
O
C
O C
CH2
Glycerol
O
Fatty acids
Hydrophilic
head
Hydrophobic
tails
Figure 5.13
(a) Structural formula
(b) Space-filling model
(c) Phospholipid
symbol
40
• The structure of phospholipids
– Results in a bilayer arrangement found in cell membranes
WATER
Hydrophilic
head
WATER
Hydrophobic
tail
Figure 5.14
41
Steroids
• Steroids
– Are lipids characterized by a carbon skeleton
consisting of four fused rings
42
• One steroid, cholesterol
– Is found in cell membranes
– Is a precursor for some hormones
H 3C
CH3
CH3
CH3
CH3
Figure 5.15
HO
43
Proteins
• Proteins have many structures,
resulting in a wide range of functions
• Proteins do most of the work in cells
and act as enzymes
• Proteins are made of monomers called
amino acids
44
• An overview of protein functions
Table 5.1
45
• Enzymes
– Are a type of protein that acts as a catalyst, speeding up
chemical reactions
1
Active site is available for
a molecule of substrate, the
reactant on which the enzyme acts.
Substrate
(sucrose)
2 Substrate binds to
enzyme.
Glucose
OH
Enzyme
(sucrase)
H 2O
Fructose
H O
4 Products are released.
Figure 5.16
3 Substrate is converted
to products.
46
Polypeptides
• Polypeptides
– Are polymers (chains) of amino acids
• A protein
– Consists of one or more polypeptides
47
• Amino acids
– Are organic molecules possessing both carboxyl and
amino groups
– Differ in their properties due to differing side chains,
called R groups
48
Twenty Amino Acids
• 20 different amino acids make up proteins
CH3
CH3
H
H3N+
C
CH3
O
H3N+
C
H
Glycine (Gly)
O–
C
H3N
C
H
+
O–
C
CH2
CH2
O
H 3N
C
H
Valine (Val)
Alanine (Ala)
CH
CH3
CH3
O
CH3
CH3
C
+
O–
O
C
H
Leucine (Leu)
H3C
H3N
+
O–
CH
C
O
C
H
Isoleucine (Ile)
O–
Nonpolar
CH3
CH2
S
NH
CH2
CH2
H3N+
C
H
H3N+
C
O–
Methionine (Met)
Figure 5.17
CH2
O
C
H
CH2
O
C
O–
Phenylalanine (Phe)
H3N+
C
H
O
C
H2C
CH2
H2
N
C
O
C
H
O–
O–
Tryptophan (Trp)
Proline (Pro)
49
OH
OH
Polar
H3N
+
CH2
C
O
C
H
CH
H3N
O–
Serine (Ser)
C
+
O
C
H3N
O–
H
+
CH2
C
H
O
C
CH2
H3N
O–
C
+
O
C
H
Electrically
charged
H3N
+
C
+
O–
O–
O
NH3+
NH2
C
CH2
C
CH2
CH2
CH2
CH2
CH2
CH2
O
H
O–
H3N
+
CH2
C
O
C
H
O–
H3N
+
CH2
C
H
Aspartic acid
(Asp)
O–
+
CH2
C
O
C
H
O–
Glutamine
(Gln)
Asparagine
(Asn)
C
C
C
H3N
Basic
O
C
CH2
O
H
Acidic
–O
CH2
H3N
Tyrosine
(Tyr)
Cysteine
(Cys)
Threonine (Thr)
C
NH2 O
C
SH
CH3
OH
NH2 O
Glutamic acid
(Glu)
O–
Lysine (Lys)
NH2+
H3N
+
CH2
O
C
NH+
H3N
+
CH2
C
H
NH
CH2
O
C C
O–
H
O
C
O–
Arginine (Arg)
Histidine (His)
50
Amino Acid Polymers
• Amino acids
– Are linked by peptide bonds
51
Protein Conformation and
Function
• A protein’s specific conformation (shape)
determines how it functions
52
•
Four Levels of Protein
Structure
Primary structure
–
Is the unique sequence
of amino acids in a
polypeptide
+H
3N
Amino
end
Amino
acid
subunits
Gly ProThrGly
Thr
Gly
Glu
Cys LysSeu
LeuPro
Met
Val
Lys
Val
Leu
Asp
AlaVal ArgGly
Ser
Pro
Ala
Glu Lle
Leu Ala
Gly
Asp
Thr
Lys
Ser
Lys TrpTyr
lle
Ser
Pro Phe
His Glu
AlaThrPhe Val
Asn
His
Ala
Glu
Val
Thr
Asp
Tyr
Arg
Ser
Arg
Gly Pro
lle
Ala
Ala
Leu
Leu
Ser
Pro
SerTyr
Tyr
Ser
Thr
Thr
Ala
Val
Val
Glu
Thr Pro Lys
Asn
Figure 5.20
c
o
o–
Carboxyl end
53
• Secondary structure
– Is the folding or coiling of the polypeptide into a repeating
configuration
– Includes the  helix and the  pleated sheet
– Be sure that you can identify what this structure looks like!
 pleated sheet
Amino acid
subunits
O H H
C C N
C N
H
R
R
C C N
O H H
C
C
R
N H
C
H
R
O C
O C
N H
N H
N H
O C
O C
H C R H C R
H C R H C
R
N H O C
N H
O C
O C
H
C
O
N H
N
C
C
H
R
R H
C
R
R
O H H
C C N
C C N
OH H
R
R
R
O
O H H
C C N
O
H
O H H
C C N
C C N
OH H
R
O
C
H
H
N HC N H C N H C N
C
H
H
C
O
C
O
R
R
C
R
O
C
H
H
NH C N
C
H
O C
R
R
C C
O
R
H
C
N HC N
H
O C
H
 helix
Figure 5.20
54
• Tertiary structure
– Is the overall three-dimensional shape of a polypeptide
– Results from interactions between amino acids and R
groups
Hyrdogen
bond
CH22
CH
O
H
O
H 3C
CH
CH3
H 3C
CH3
CH
Hydrophobic
interactions and
van der Waals
interactions
Polypeptide
backbone
HO C
CH2
CH2 S S CH2
Disulfide bridge
O
CH2 NH3+-O C CH2
Ionic bond
55
• Quaternary structure
– Is the overall protein structure that results from the
aggregation of two or more polypeptide subunits
Polypeptide
chain
Collagen
 Chains
Iron
Heme
 Chains
Hemoglobin
56
Review of Protein
Structure
+H
3N
Amino end
Amino acid
subunits
helix
57
Sickle-Cell Disease: A Simple Change
in Primary Structure
• Sickle-cell disease
– Results from a single amino acid
substitution in the protein hemoglobin
58
Primary
structure
Normal hemoglobin
Val
His Leu Thr Pro Glul Glu
1 2 3 4 5 6 7
Secondary
and tertiary
structures
Red blood
cell shape
Figure 5.21
Val
His
Leu Thr Pro


Molecules do
not associate
with one
another, each
carries oxygen.
Normal cells are
full of individual
hemoglobin
molecules, each
carrying oxygen


Val
Glu
structure 1 2 3 4 5 6 7
Secondary
 subunit and tertiary
structures
Quaternary Hemoglobin A
structure
Function
Sickle-cell hemoglobin
. . . Primary
Quaternary
structure
Function
10 m
...
Exposed
hydrophobic
region
 subunit




10 m
Hemoglobin S
Molecules
interact with
one another to
crystallize into a
fiber, capacity
to carry oxygen
is greatly
reduced.
Red blood
cell shape
Fibers of
abnormal
hemoglobin
deform cell into
sickle shape.
59
What Determines Protein
Conformation?
• Protein conformation Depends on the
physical and chemical conditions of the
protein’s environment
• Temperature, pH, etc. affect protein
structure
60
•Denaturation is when a protein
unravels and loses its native
conformation
(shape)
Denaturation
Normal protein
Figure 5.22
Denatured protein
Renaturation
61
The Protein-Folding
Problem
• Most proteins
– Probably go through several intermediate states on their way to a
stable conformation
– Denaturated proteins no longer work in their unfolded condition
– Proteins may be denaturated by extreme changes in pH or
temperature
62
• Chaperonins
– Are protein molecules that assist in the proper folding of
other proteins
Cap
Polypeptide
Correctly
folded
protein
Hollow
cylinder
Steps of Chaperonin
Chaperonin
(fully assembled) Action:
An unfolded poly1
peptide enters the
cylinder from one
Figure 5.23
end.
The cap attaches, causing
The cap comes
3
the cylinder to change shape off, and the
in
properly
such a way that it creates a
folded protein is
hydrophilic environment for
released.
the folding of the polypeptide.
2
63
• X-ray crystallography
–
Is used to determine a protein’s three-dimensional
structure
Photographic
film
Diffracted
X-
rays
X-ray
source
X-ray
diffraction
pattern
X-ray
beam
Crystal Nucleic acid Protein
Figure 5.24
(b) 3D computer model
(a) X-ray diffraction pattern
64
Nucleic Acids
• Nucleic acids store and transmit
hereditary information
• Genes
– Are the units of inheritance
– Program the amino acid sequence of
polypeptides
– Are made of nucleotide sequences on DNA
65
•
The Roles of Nucleic
Acids
There are two types of nucleic acids
– Deoxyribonucleic acid (DNA)
– Ribonucleic acid (RNA)
66
Deoxyribonucleic Acid
• DNA
– Stores information for the synthesis of
specific proteins
– Found in the nucleus of cells
67
DNA Functions
– Directs RNA synthesis (transcription)
– Directs protein synthesis through RNA (translation)
DNA
1 Synthesis of
mRNA in the nucleus
NUCLEUS
2 Movement of
mRNA into cytoplasm
via nuclear pore
mRNA
CYTOPLASM
mRNA
Ribosome
3 Synthesis
of protein
Figure 5.25
Polypeptide
Amino
acids
68
The Structure of Nucleic
Acids
• Nucleic acids
– Exist as polymers called
polynucleotides
5’ end
5’C
O
3’C
O
O
5’C
O
3’C
(a) Polynucleotide,
or nucleic acid
Figure 5.26
OH
3’ end
69
70
• Each polynucleotide
– Consists of monomers called nucleotides
– Sugar + phosphate + nitrogen base
Nucleoside
Nitrogenous
base
O

O
P
5’C
O
CH2
O
O
Phosphate
group
Figure 5.26
3’C
Pentose
sugar
(b) Nucleotide
71
Nucleotide Monomers
• Nucleotide monomers
– Are made up of
nucleosides (sugar + base)
NH
and phosphate groups
C
Nitrogenous bases
Pyrimidines
O
O
2
C
C
CH3
N
CH
C
CH HN
HN
CH
C
CH
C
C
CH
N
N
O
N
O
O
H
H
H
Cytosine Thymine (in DNA)Uracil
(in RNA)
RNA)
Uracil (in
U
C
U
T
Purines
O
NH2
N C C
N C C
NH
N
HC
HC
C
CH
N C
N
NH2
N
N
H
H
Adenine
Guanine
A
G
5”
Pentose sugars
HOCH2 O
4’
OH
H H
1’
5”
HOCH2 O OH
4’
H H
1’
H
H
H 3’ 2’ H
3’ 2’
OH H
OH OH
Deoxyribose (in DNA) Ribose (in RNA)
Figure 5.26
(c) Nucleoside components
72
Nucleotide Polymers
• Nucleotide polymers
– Are made up of nucleotides linked by the–OH
group on the 3´ carbon of one nucleotide and
the phosphate on the 5´ carbon on the next
73
74
75
Be sure that you can
recognize a single
strand of DNA
76
Gene
• The sequence of bases along a nucleotide
polymer
– Is unique for each gene
77
The DNA Double Helix
• Cellular DNA molecules
– Have two polynucleotides that spiral around an
imaginary axis
– Form a double helix
– Check this out
78
• The DNA double helix
– Consists of two antiparallel nucleotide strands
5’ end
3’ end
Sugar-phosphate
backbone
Base pair (joined by
hydrogen bonding)
Old strands
A
3’
end
Nucleotide
about to be
added to a
new strand
5’ end
3’ end
Figure 5.27
5’ end
New
strands
3’ end
79
A,T,C,G
• The nitrogenous bases in DNA
– Form hydrogen bonds in a complementary fashion (A
with T only, and C with G only)
80
DNA and Proteins as Tape
Measures of Evolution
• Molecular comparisons
– Help biologists sort out the
evolutionary connections among species
81
The Theme of Emergent Properties
in the Chemistry of Life: A Review
• Higher levels of organization
– Result in the emergence of new properties
•
Organization
– Is the key to the chemistry of life
82
Large biological
molecules
Carbohydrates
Functions
Components
Examples
Monosaccharides:
glucose, fructose
Disaccharides:
lactose, sucrose
Polysaccharides:
starch, cellulose
Dietary energy;
storage; plant
structure
Monosaccharide
Lipids
Long-term
energy storage
fats;
hormones
steroids
Fatty acid
Glycerol
Components of
a triglyceride
Amino
group
Proteins
Enzymes, structure,
storage, contraction,
transport, and others
Fats triglycerides;
Steroids
testosterone,
estrogen
Carboxyl
group
Side
group
Lactase
an enzyme,
hemoglobin
a transport protein
Amino acid
Phosphate
Base
Nucleic acids
Information
storage
DNA, RNA
Sugar
Nucleotide
Figure UN3-2
83