Download Macromolecule Lecture

Macromolecules
Honors Biology
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• The building materials of the body are known as
macromolecules because they can be very large
• There are four types of macromolecules:
1. Proteins
2. Nucleic acids
3. Carbohydrates
4. Lipids
• Large macromolecules are actually assembled
from many similar small components, called
monomers
– the assembled chain of monomers is known as
a polymer
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Assembling Polymers
• All polymers are assembled the same way
• A molecule of water (H2O) is removed
• Process is called dehydration synthesis
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Figure 3.3(a) Dehydration synthesis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H2 O
HO
H
H HO
Energy
HO
(a) Dehydration synthesis
H
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Disassembling Polymers
• essentially the reverse of dehydration
synthesis
• a molecule of water is added to break the
covalent bond between the monomers
• this process is known as hydrolysis
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Figure 3.3(b) Hydrolysis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H 2O
H
HO
Energy
HO
(b) Hydrolysis
H HO
H
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What are Proteins
• subunits called amino acids
• the covalent bond linking two amino acids
together is called a peptide bond
• the assembled polymer is called a
polypeptide
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Figure 3.5 The formation of a peptide bond
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Amino acid
H
Amino acid
H
R
N
C
C
H
O
H
OH
H
R
N
C
C
H
O
OH
H2O
Polypeptide chain
H
H
R
N
C
C
H
O
H
R
N
C
C
H
O
OH
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Four Levels of Protein Structure
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
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Structure vs. Function
• The shape of a protein affects its function
• changes to the environment of the protein
may cause it to unfold or denature (become
inactive)
– increased temperature
– lower pH
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3.3 Nucleic Acids
•
Function: store information
•
Monomers: nucleotides
•
Each nucleotide has 3 parts
1. a five-carbon sugar
2. a phosphate group
3. an organic nitrogen-containing base
• There are five different types of nucleotides
– information is encoded in the nucleic acid by
different sequences of these nucleotides
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Figure 3.9 The structure of a nucleotide
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Structure of nucleotide
7N
Phosphate group
P
N
9
O
4
O
NH2
N
1
H
N C C
N
N C
C H
C
2
N
3
H
N
C
H
CH2
5
4
1
3
2
OH
H C
OH in RNA
H C
R
Sugar
C
N
N C
NH2
N
C
O
N
C O
H
H in DNA
H
Guanine
NH2
O
N C C N
H
Adenine
O–
(a)
5
NH2
6
8
O
–O
Nitrogenous bases
Nitrogenous base
Cytosine
H3C
C
H C
C
N
O
N H
H
C
C
H
C
H
Thymine (DNA only)
O
C
N
N
H
C O
H
Uracil (RNA only)
(b)
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3.3 Nucleic Acids
• There are two types of nucleic acids
– Deoxyribonucleic acid (DNA)
– Ribonucleic acid (RNA)
• RNA is similar to DNA except that
– it uses uracil instead of thymine
– it is comprised of just one strand
– it has a ribose sugar
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What are Carbohydrates?
• Carbohydrates are monomers that make up the
structural framework of cells and play a critical
role in energy storage
• A carbohydrate is any molecule that contains the
elements C, H, and O in a 1:2:1 ratio
• The sizes of carbohydrates varies
– simple carbohydrates—consist of one or two
monomers
– complex carbohydrates—are long polymers
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3.4 Carbohydrates
• Simple carbohydrates are small
– monosaccharides consist of only one
monomer subunit
• an example is the sugar glucose (C6H12O6)
– disaccharides consist of two monosaccharides
• an example is the sugar sucrose, which is
formed by joining together glucose and
fructose
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Figure 3.13 Formation of sucrose
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3.4 Carbohydrates
• Complex carbohydrates are long
polymer chains
– because they contain many C-H bonds, these
carbohydrates are good for storing energy
• these bond types are the ones most often
broken by organisms to obtain energy
– the long chains are called polysaccharides
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3.4 Carbohydrates
• Plants and animals store energy in
polysaccharide chains formed from glucose
– plants form starch
– animals form glycogen
• Some polysaccharides are structural and
resistant to digestion by enzymes
– plants form cellulose cell walls
– some animals form chitin for exoskeletons
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3.5 Lipids
• Lipids—fats and other molecules that are
not soluble in water
– lipids are nonpolar molecules
– there are many different types of lipids
• fats
• oils
• steroids
• rubber
• waxes
• pigments
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3.5 Lipids
• Fats are converted from glucose for longterm energy storage
• Fats have two subunits
– 1. fatty acids
– 2. glycerol
– Fatty acids are chains of C and H atoms,
known as hydrocarbons
• the chain ends in a carboxyl (—COOH)
group
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Figure 3.15 Saturated and unsaturated fats
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H
Because there
are 3 fatty acids
attached to a
glycerol,
another name
for a fat is
triglyceride
H
H
H
O H
H
H
H
H
H
H
H
C O
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
O H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
O H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
C O
C O
H
Glycerol
backbone
H
H
H
Fatty acids
(a) Fat molecule (triacylglycerol)
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3.5 Lipids
• Fatty acids have different chemical
properties due to the number of hydrogens
that are attached to the non-carboxyl
carbons
– if the maximum number of hydrogens are
attached, then the fat is said to be
saturated
– if there are fewer than the maximum
attached, then the fat is said to be
unsaturated
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Figure 3.15 Saturated and unsaturated fats
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H
H
H
H
C
C
C
C
H
H
(b) Hard fat (saturated): Fatty
acids with single bonds
between all carbon pairs
(c) Oil (unsaturated): Fatty acids
that contain double bonds
between one or more pairs
of carbon atoms
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• Biological membranes involve lipids
– phospholipids make up the two layers of the
membrane
– cholesterol is embedded within the membrane
Figure 3.17 Lipids are a key component of biological membranes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Outside of cell
Carbohydrate chains
Cell
membrane
Membrane proteins
Phospholipid
Cholesterol
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Inside of cell
Inquiry & Analysis
How Does pH Affect a Protein’s
Function?
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• In the graph, what is the
dependent variable?
Effects of pH on Hemoglobin O2Binding
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pH 7.60
pH 7.40
pH 7.20
• Which of the three pH values
represents the highest
concentration of hydrogen
ions?
• How does pH affect the
release of oxygen from
hemoglobin?
Percent hemoglobin bound to O2
90
80
70
60
50
40
30
20
10
0
0
20
40
60
80
100
120
140
Oxygen levels (measured in mm Hg)
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