Download (a) (c)

Chemistry of
Organic Molecules
Ch. 3
Essential Knowledge (AP
Exam)
• Organisms must exchange matter with the
environment to grow, reproduce and
maintain organization. EK 2.A.3
• Evidence of understanding:
– Carbon  carbohydrates, proteins, lipids,
nucleic acids
– Nitrogen  proteins, nucleic acids
– Phosphorus  nucleic acids, some lipids
Activity
• Draw a simple diagram of how the
following is cycled through the
environment so that it is exchanged with
living organisms.
• Pages 876-878 in textbook
3.1 Organic Molecules
• Organic molecules contain carbon and
hydrogen atoms.
• Four classes of organic molecules
(biomolecules) exist in living organisms:
– Carbohydrates
– Lipids
– Proteins
– Nucleic Acids
4
Carbon: The Atom
• Carbon has 4 valence
electrons
– Therefore, it can form 4
covalent bonds
– can bond with up to 4
different atoms
– can form double and
triple bonds
The structure of the carbon atom
determines its function!
Carbon Skeleton Diversity
• Organic molecules are diverse in large part due to
the variation in carbon skeletons
• Which is more flexible- double or single bonds?
The Carbon Skeleton and Functional Groups
• The carbon chain of an organic molecule is
called its skeleton or backbone.
• Hydrogen and Carbon have similar
electronegativity = non-polar
• Functional groups are clusters of specific
atoms bonded to the carbon skeleton
– have characteristic structures and functions
– determine the polarity of organic molecules
and the types of reactions the molecule will
undergo
• See handout Figure 4.9
7
Isomers
• Isomers are organic molecules that have
identical molecular formulas but a different
arrangement of atoms.
• Name the two different functional groups:
glyceraldehyde
H
H
H
O
C
C
C
OH OH
H
dihydroxyacetone
H
H
O
H
C
C
C
OH
H
OH
• Will these react differently? Why?
8
Biomolecules
• Carbohydrates, lipids, proteins, and nucleic
acids are called biomolecules.
– Usually consist of many repeating units
• Each repeating unit is called a monomer.
• A molecule composed of monomers is
called a polymer (many parts).
9
Essential Knowledge (AP
Exam)
• The subcomponents of biological
molecules and their sequence determine
the properties of that molecule. (EK4.A.1)
– The structure and function of polymers are
derived from the way their monomers are
assembled.
Activity
• Making Models of Macromolecules
Glucose is a monomer
• Make a ball and stick glucose model.
• C6H O6
12
• Combine your glucose model with another
glucose model at the #1 Carbon of one
model and the #4 Carbon of the other
model.
• What must occur?
The Synthesis of Polymers
• A condensation reaction or dehydration
reaction occurs when two monomers bond
together through the loss of a water molecule
Fig. 5-2a
HO
1
2
3
H
Short polymer
HO
Unlinked monomer
Dehydration removes a water
molecule, forming a new bond
HO
1
2
H
3
H2O
4
H
Longer polymer
(a) Dehydration reaction in the synthesis of a polymer
The Breakdown of Polymers
• Polymers are disassembled to monomers
by hydrolysis, a reaction that is
essentially the reverse of the dehydration
reaction
Fig. 5-2b
HO
1
2
3
4
Hydrolysis adds a water
molecule, breaking a bond
HO
1
2
3
(b) Hydrolysis of a polymer
H
H
H2O
HO
H
Synthesis and Degradation
• Enzymes are required for cells to carry out
dehydration synthesis and hydrolysis reactions.
– An enzyme is a molecule that speeds up a
chemical reaction.
• Enzymes are not consumed in the reaction.
• Enzymes are not changed by the reaction.
18
3.2 Carbohydrates
• Functions:
– Immediate energy source
– Provide building material (structural role)
• Contain carbon, hydrogen and oxygen in a 1:2:1
ratio
• Varieties: monosaccharides, disaccharides, and
polysaccharides
Essential Knowledge (AP
Exam)
EK4.A.1.a.4
• Carbohydrates are composed of sugar
monomers whose structures and bonding with
each other by dehydration synthesis determine
the properties and functions of the molecules.
• You must demonstrate an understanding of the above
and the example of cellulose versus starch
• You must be able to explain and use models to justify
the connection between the structure and function of
the polymers.
Monosaccharides
• A monosaccharide is a single sugar molecule.
• Also called simple sugars
• Have a backbone of 3 to 7 carbon atoms
• Examples:
– Glucose (blood), fructose (fruit) and galactose
• Hexoses - six carbon atoms
– Ribose and deoxyribose (in nucleotides)
• Pentoses – five carbon atoms
21
•
What 2 functional groups are the
trademarks of a sugar molecule?
•
Functional groups of sugars:
– Carbonyl groups
– Hydroxyl groups
Fig. 5-4a
•In aqueous solutions many sugars form rings
(a) Linear and ring forms
Monosaccharide Function
• Monosaccharides serve as a major fuel for
cells and as raw material for building
molecules
Disaccharide Structure
• A disaccharide is formed when a
dehydration reaction joins two
monosaccharides
• This covalent bond is called a glycosidic
linkage
Fig. 5-5
1–4
glycosidic
linkage
Glucose
Glucose
Maltose
1–2
glycosidic
linkage
Glucose
Fructose
Lactose = glucose + galactose
Sucrose
Polysaccharides
• Polysaccharides
– polymers of sugars
– Function: energy storage and structural
• The structure and function of a polysaccharide
are determined by
– its sugar monomers
– the positions of glycosidic linkages
Storage Polysaccharides
• Starch
– An energy storage polysaccharide in plants
– consists entirely of glucose monomers
• Plants store surplus starch as granules
within chloroplasts and other plastids
Storage Polysaccharides
• Glycogen
– An energy storage polysaccharide in animals
• Humans and other vertebrates store
glycogen mainly in liver and muscle cells
Fig. 5-6
Chloroplast
Mitochondria Glycogen granules
Starch
0.5 µm
1 µm
Glycogen
Amylose
Amylopectin
(a) Starch: a plant polysaccharide
(b) Glycogen: an animal polysaccharide
What is the difference? How is glucose released?
Structural Polysaccharides
• Cellulose
–major component of the tough wall of
plant cells
–a polymer of glucose
• the glycosidic linkages differ from that of
starch
• difference is based on two ring forms for
glucose: alpha () and beta ()
Fig. 5-7
(a)  and B glucose
ring structures
 Glucose
(b) Starch: 1–4 linkage of  glucose monomers
B Glucose
(b) Cellulose: 1–4 linkage of B glucose monomers
• Polymers with  glucose are helical
• Polymers with  glucose are straight
• The differing glycosidic linkages give the two
molecules their distinct shapes.
• In Cellulose the straight molecules can form
hydrogen bonds with each other  greater
strength
isomers of glucose
 structure determines function…

Fig. 5-8
Cell walls
Cellulose
microfibrils
in a plant
cell wall
Microfibril
10 µm
0.5 µm
Cellulose
molecules
b Glucose
monomer
• Enzymes that digest starch can’t hydrolyze
cellulose
– Cellulose in human food passes through the
digestive tract as insoluble fiber
• Some microbes use enzymes to digest
cellulose
– Many herbivores, from cows to termites, have
symbiotic relationships with these microbes
Helpful bacteria
• How can herbivores digest cellulose so well?
– BACTERIA live in their digestive systems & help digest
cellulose-rich (grass) meals
Ruminants
• Chitin, another structural polysaccharide, is
found in the exoskeleton of arthropods
• Chitin also provides structural support for
the cell walls of many fungi
The structure
of the chitin
monomer.
Chitin forms the
exoskeleton of
arthropods.
Chitin is used to make
a strong and flexible
surgical thread. It has
anti viral and anti fungal
Properties.
Chitin
Essential Knowledge AP Exam
• (EK4.A.a.a.3) In general lipids are
nonpolar. Phospholipids exhibit structural
properties, with polar regions that interact
with polar molecules (water) and with
nonpolar regions where differences in
saturation determine the structure and
function of lipids.
3.3 Lipids
• Lipids are varied in structure.
• Large nonpolar molecules that are insoluble in water
• Functions:
 Long-term energy storage
 Structural components
 Cell communication and regulation
 Protection
• Varieties: fats, oils, phospholipids, steroids, waxes
Triglycerides: Long-Term
Energy Storage
– Also called fats and oils
– Functions: long-term energy storage and
insulation
– Consist of one glycerol molecule linked to
three fatty acids by dehydration synthesis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H
C
C
H
H
H
C
C
C
C
C
H
H
H
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
OH
H
H
H
H
H
H
H
H
H
H
C
C
C
O
C
HO
O
C
H
C
OH
H
glycerol
a Formation of a fat
.
H
HO
OH
+
H
H
O
C
H
H
HO
H
H
H
C
C
H
H
3 fatty acids
H
H
in
What is the process that causes fat to form?
Fig. 5-11
Fatty acid
(palmitic acid)
Glycerol
(a) Dehydration reaction in the synthesis of a fat
Ester linkage
(b) Fat molecule (triacylglycerol)
What is the Difference?
Triglycerides: Long-Term Energy Storage
• Fatty acids are either unsaturated or saturated.
– Unsaturated - one or more double bonds between
carbons
• Tend to be liquid at room temperature
– Example: plant oils
– Saturated - no double bonds between carbons
• Tend to be solid at room temperature
– Examples: butter, lard
Why are unsaturated fats liquid at room
temperature?
45
Saturated vs Unsaturated
Mostly animal products
Mostly plant products
• A diet rich in saturated fats may contribute to
cardiovascular disease through plaque
deposits
• Hydrogenation is the process of converting
unsaturated fats to saturated fats by adding
hydrogen
• Hydrogenating vegetable oils also creates
unsaturated fats with trans double bonds
• These trans fats may contribute more than
saturated fats to cardiovascular disease
Fat Function
• 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
Phospholipids
• Phospholipid
– two fatty acids and a phosphate group
are attached to glycerol
• the two fatty acid tails are hydrophobic
• the phosphate group and its
attachments form a hydrophilic head
• The molecule is amphipathic
Hydrophilic head
Fig. 5-13
Choline
Phosphate
Hydrophobic tails
Glycerol
Fatty acids
Hydrophilic
head
Hydrophobic
tails
(a) Structural formula
(b) Space-filling model
What causes the tails to be nonpolar?
(c) Phospholipid symbol
Function of Phospholipids
• Phospholipids are the major component of all
cell membranes
• When phospholipids are added to water, they
self-assemble into a bilayer, with the
hydrophobic tails pointing toward the interior
What causes the
phospholipids to
arrange this way?
Phospholipids Form
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Membranes
glycerol
O
Polar
Head
1
O
CH2
2
CH2
3
R O P O CH2
O
Fig. 3.11
CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH
CH2 CH2
2 CH2 CH3
CH
2
C
fatty acids
O
C CH2 CH
2 CH2 CH2 CH2 CH2 CH2 CH
O
Nonpolar Tails
phosphate
b.. Plasma membrane of a cell
outside cell
inside cell
a. Phospholipid structure
Steroids
• Steroids are lipids characterized by a carbon
skeleton consisting of four fused rings
• Cholesterol, an important steroid, is a
component in animal cell membranes
• Examples: cholesterol, testosterone, estrogen
• Although cholesterol is essential in animals,
high levels in the blood may contribute to
cardiovascular disease
Steroid Diversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
OH
CH3
CH3
O
b. Testosterone
CH3
HC
CH3
(CH2)3
HC
CH3
OH
CH3
CH3
CH3
HO
c. Estrogen
HO
a. Cholesterol
© Ernest A. Janes/Bruce Coleman/Photoshot
Compare the testosterone and estrogen molecules.
Demonstration
• Grape demonstration:
• Why is this occurring?
Waxes
• Long-chain fatty acid bonded to a long-chain
alcohol
• Solid at room temperature
• Waterproof
• Resistant to degradation
• Function: protection
• Examples: earwax, plant cuticle, beeswax,
fruit covering
Essential Knowledge AP Exam
• (EK 4.A.1.a.2) In proteins, the specific
order of animo acids in a polypeptide
interacts with the environment to
determine the overall shape of the protein,
which also involves secondary and
quaternary structure and, thus, its function.
3.4 Proteins
• Proteins are polymers of amino acids linked
together by peptide bonds.
 A peptide bond is a covalent bond between amino
acids.
• Two or more amino acids joined together are
called peptides.
 Long chains of amino acids joined together are
called polypeptides.
• A protein is a polypeptide that has folded into
a particular shape and has function.
58
Functions of Proteins
• Metabolism
 Most enzymes are proteins that act as catalysts to accelerate
chemical reactions within cells.
• Support
 Keratin and collagen
• Transport
 Hemoglobin and membrane proteins
• Defense
 Antibodies
• Regulation
 Hormones are regulatory proteins that influence the metabolism of
cells.
• Motion
 Muscle proteins and microtubules
59
Amino Acids: Protein Monomers
• There are 20 different common amino acids.
• Amino acids differ by their R groups.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
amino
group
H2N
H
C
R
R = rest of molecule
acidic
group
COOH
(EK4.A.1.2) The R group of an amino acid
can be categorized by chemical
properties and these R groups determine
structure and function of that region of
the protein.
• Amino acids can be classified according
to the properties of their side chains (R
groups):
– Nonpolar
– Polar
– electrically charged (acidic or basic)
Fig. 5-17a
Nonpolar
Glycine
(Gly or G)
Methionine
(Met or M)
Alanine
(Ala or A)
Valine
(Val or V)
Phenylalanine
(Phe or F)
Leucine
(Leu or L)
Tryptophan
(Trp or W)
Isoleucine
(Ile or I)
Proline
(Pro or P)
Fig. 5-17b
Polar
Serine
(Ser or S)
Threonine
(Thr or T)
Cysteine
(Cys or C)
Tyrosine
(Tyr or Y)
Asparagine Glutamine
(Asn or N) (Gln or Q)
Fig. 5-17c
Electrically
charged
Acidic
Aspartic acid Glutamic acid
(Glu or E)
(Asp or D)
Basic
Lysine
(Lys or K)
Arginine
(Arg or R)
Histidine
(His or H)
Synthesis and Degradation of a Peptide
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
amino group
amino acid
Fig. 5-18
Peptide
bond
What type of
reaction is this?
(a)
Side chains
Peptide
bond
Backbone
(b)
Amino end
(N-terminus)
Carboxyl end
(C-terminus)
Levels of Protein Structure
• Proteins cannot function properly unless they
fold into their proper shape.
– When a protein loses it proper shape, it said
to be denatured.
• Exposure of proteins to certain chemicals,
a change in pH, or high temperature can
disrupt protein structure.
• Proteins can have up to four levels of structure:
–
–
–
–
Primary
Secondary
Tertiary
Quaternary
67
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H3N+
Primary Structure
This level of structure
is determined by the
sequence of amino
acids coded by a
gene that joins to
form a polypeptide.
amino acid
C
O
C
CH
R
N R
H
O
O
C
CH
N
H
H
O
O
CH
R
R
hydrogen bond
C
C
C
N H
O
H
C
R C
O H
N
N
C
C
N
R C
N
CH
N R
H
C
hydrogen bond
O
C
O
O
R
H
N R
H
C
Hydrogen bonding
between amino
acids causes the
polypeptide
to form an alpha
helix or a pleated
sheet.
N
CH
CH
Secondary Structure
CH
C
O
COO–
peptide bond
C R
C
N H
R C
O C
R C
C O
H
H N
N
CH
R C
C O
C R
N H
H
O
R C
C
α alpha) helix
O
N
H
Β (beta) sheet = pleated sheet
disulfide bond
Quaternary Structure
This level of structure
occurs when two or more
folded polypeptides interact
to perform a biological function.
H
C O
N
C
C
N
C
O
Tertiary Structure
Interactions of amino
acid side chains with
water, covalent bonding
between R groups, and
other chemical interactions
determine the folded
three-dimensional shape
of a protein.
C
C
N
O
R
Four Levels of Protein Structure
1. 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
2. Secondary structure
• coils and folds resulting from hydrogen
bonds between repeating constituents of
the polypeptide backbone
• Typical secondary structures are a coil
called an  helix and a folded structure
called a  pleated sheet
Fig. 5-21c
Secondary Structure
B pleated sheet
Examples of
amino acid
subunits
 helix
3. Tertiary structure
– determined by interactions between R groups,
rather than interactions between backbone
constituents
•
•
•
•
hydrogen bonds
ionic bonds
hydrophobic interactions
van der Waals interactions
– Strong covalent bonds called disulfide
bridges may reinforce the protein’s structure
Fig. 5-21f
Hydrophobic
interactions and
van der Waals
interactions
Polypeptide
backbone
Hydrogen
bond
Disulfide bridge
Ionic bond
Fig. 5-21e
Tertiary Structure
Quaternary Structure
4.Quaternary structure results when two or
more polypeptide chains form one
macromolecule
• Collagen is a fibrous protein consisting of
three polypeptides coiled like a rope
• Hemoglobin is a globular protein consisting
of four polypeptides: two alpha and two beta
chains
Fig. 5-21g
Polypeptide
chain
B Chains
 Chains
Hemoglobin
Collagen
Fig. 5-22
Normal hemoglobin
Primary
structure
Val His Leu Thr Pro Glu Glu
1
2
3
4
5
6
7
Secondary
and tertiary
structures
B subunit
Normal
hemoglobin
(top view)
1
2
3
Normal red blood
cells are full of
individual
hemoglobin
molecules, each
carrying oxygen.
6
7
B subunit
B
Sickle-cell
hemoglobin
a
Function
a
Molecules
interact with
one another and
crystallize into
a fiber; capacity
to carry oxygen
is greatly reduced.
10 µm
Red blood
cell shape
5
Exposed
hydrophobic
region
B
Molecules do
not associate
with one
another; each
carries oxygen.
4
a
Quaternary
structure
B
Function
Secondary
and tertiary
structures
Val His Leu Thr Pro Val Glu
B
a
Quaternary
structure
Sickle-cell hemoglobin
Primary
structure
10 µm
Red blood
cell shape
Fibers of abnormal
hemoglobin deform
red blood cell into
sickle shape.
Why are these two hemoglobin structures different?
Essential Knowledge AP Exam
• Alterations in a DNA sequence can lead to
changes in the type and amount of the
protein produced and the consequent
phenotype.
• A change in the order of amino acids could
lead to different R groups and interactions
between those R groups. This could
change the shape of the molecule  &
may change its function.
What Can Change 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
Fig. 5-23
Denaturation
Normal protein
Renaturation
Denatured protein
If the denatured protein remains dissolved it may be able
to renature once the environment is returned to normal.
Animation of Denaturation
• http://www.sumanasinc.com/webcontent/a
nimations/content/proteinstructure.html
Fig. 5-24
•Chaperonins are protein molecules that assist the proper
folding of other proteins
Polypeptide
Correctly
folded
protein
Cap
Hollow
cylinder
Chaperonin
(fully assembled)
Steps of Chaperonin 2
Action:
1 An unfolded polypeptide enters the
cylinder from one end.
The cap attaches, causing the 3 The cap comes
cylinder to change shape in
off, and the properly
such a way that it creates a
folded protein is
hydrophilic environment for
released.
the folding of the polypeptide.
Defects in chaperone proteins may play a role in
several human diseases such as Alzheimer disease
and cystic fibrosis.
Protein-Folding Diseases
• Prions are misfolded proteins that have been
implicated in a group of fatal brain diseases
known as TSEs.
– Mad cow disease is one example of a TSE disease.
83
• Enzymes are a type of protein that acts as a
catalyst to speed up chemical reactions
• Enzymes can perform their functions repeatedly,
functioning as workhorses that carry out the
processes of life
Fig. 5-16
Substrate
(sucrose)
Glucose
OH
Fructose
HO
Enzyme
(sucrase)
H2O
Essential Knowledge AP Exam
• Alterations in a DNA sequence can lead to
changes in the type and amount of the
protein produced and the consequent
phenotype.
• A change in the order of amino acids could
lead to different R groups and interactions
between those R groups. This could
change the shape of the molecule  &
may change its function.
Essential Knowledge AP Exam
• (EK3.A.1.a.1) Genetic information is
stored in and passed to subsequent
generations through DNA molecules and
in some cases RNA molecules.
3.5 Nucleic Acids
• Nucleic acids are polymers of nucleotides.
• Two varieties of nucleic acids:
– DNA (deoxyribonucleic acid)
• Genetic material that stores information for its own
replication and for the sequence of amino acids in
proteins.
– RNA (ribonucleic acid)
• Perform a wide range of functions within cells
which include protein synthesis and regulation of
gene expression
88
Structure of a Nucleotide
• Each nucleotide is composed of three parts:
– A phosphate group
– A pentose sugar
– A nitrogen-containing (nitrogenous) base
• There are five types of nucleotides found in nucleic
acids.
– DNA contains adenine, guanine, cytosine, and thymine.
– RNA contains adenine, guanine, cytosine, and uracil.
• Nucleotides are joined together by a series of
dehydration synthesis reactions to form a linear
molecule called a strand.
89
Nucleotides
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
phosphate
P
C
O
5'
4'
S
1'
2'
3'
pentose sugar
nitrogencontaining
base
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
O
–O
P
O
C
phosphate P
O–
O
5'
4'
S
1'
2'
3'
pentose sugar
a. Nucleotide structure
nitrogencontaining
base
Structure of DNA and RNA
• The backbone of the nucleic acid strand is
composed of alternating sugar-phosphate
molecules.
– RNA is predominately a single-stranded molecule.
– DNA is a double-stranded molecule.
• DNA is composed of two strands
– held together by hydrogen bonds between the
nitrogen-containing bases.
– Why Hydrogen Bonds?????
– The two strands twist around each other to
form a double helix.
93
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
RNA Structure
Fig. 3.19
N
O
N
P
G N
N
NH2
S
H
N
O
P
N
S
Nitrogen-containing
bases
O
U
CH3
Backbone
NH2
N
P
N
N
S
S Ribose
C Cytosine
A
Guanine
G
Adenine
P Phosphate U Uracil
A N
N
O
P
N
S
C
NH2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
T
A
C
G
T
A
Adenine hydrogen
bonds with thymine
G
C
Cytosine hydrogen
bonds with guanine
C CCytosine S Sugar
Guanine A AAdenine
GG
P Phosphate T TThymine
b. Double helix
a. Space-filling model
N
O
H
N
―
N
―
―
N
N
H
O
H
N
N
sugar
N
sugar
cytosine (C)
H
guanine (G)
H
N
N
―
The bonding is
complementary
H
CH3
O
H
C
N
suga r
N
H
N
N
N
O
adenine (A)
sugar
thymine (T)
c. Complementary base pairing
© Photodisk Red/Getty RF
A Special Nucleotide: ATP
• ATP (adenosine triphosphate) is composed of adenine,
ribose, and three phosphates.
• ATP is a high-energy molecule due to the presence of
the last two unstable phosphate bonds.
• Hydrolysis of the terminal phosphate bond yields:
– The molecule ADP (adenosine diphosphate)
– An inorganic phosphate
– Energy to do cellular work
• ATP is called the energy currency of the cell.
98
ATP
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a.
adenosine
triphosphate
c.
NH2
NH2
N
N
N
H2O
P
N
adenosine
b.
P
P
triphosphate
ATP
N
N
N
P
N
adenosine
P
diphosphate
ADP
c: © Jennifer Loomis / Animals Animals / Earth Scenes
+
P
phosphate
+
ENERGY
Can DNA help to demonstrate
the Theory of Evolution?
• The linear sequences of nucleotides in DNA
molecules are passed from parents to
offspring
• Two closely related species are more similar
in DNA than are more distantly related
species
• Molecular biology can be used to assess
evolutionary kinship (DNA Sequencing)