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●GE Survey-available on Blackboard
●Tutoring Center
SCI I, 407
M 12-3, 5:30-6:30; W 8-9, 5:30-6:30,
Th 8-12, 6-7; F 8-9
●MasteringBiology Assignment
Review
●Process of Science
●Chemistry of Life
atoms, elements, chemical bonding
●Properties of Water
Carbon and Organic Chemistry
– Carbon is a versatile atom.
– Carbon forms large, complex, and diverse molecules
necessary for life’s functions.
– Organic compounds are carbon-based molecules.
Structural
formula
Ball-and-stick
model
Space-filling
model
Hydrocarbons
– Larger hydrocarbons form fuels for engines.
– Hydrocarbons of fat molecules fuel our bodies.
Carbon and Organic Chemistry
• Variations in Carbon
skeletons
Carbon skeletons vary in length
Carbon skeletons may be unbranched or branched
Carbon skeletons may have double bonds,
which can vary in location
Carbon skeletons may be arranged in rings
Carbon and Organic Chemistry
• The unique properties of an organic compound
depend not only on its carbon skeleton but also on the
atoms attached to the skeleton
– These atoms are called functional groups
– Some common functional groups include:
Hydroxyl group
Carbonyl group
Amino group
Carboxyl group
Found in alcohols
and sugars
Found in sugars
Found in amino acids
and urea in urine (from
protein breakdown)
Found in amino acids,
fatty acids, and some
vitamins
Macromolecules
– On a molecular scale, many of life’s molecules are
gigantic, earning the name macromolecules.
– Three categories of macromolecules are
• Carbohydrates
• Proteins
• Nucleic acids
Macromolecules
*most macromolecules are polymers
polymer
monomer
The making and breaking of polymers:
Dehydration reaction:
Hydrolysis:
Carbohydrates
• Carbohydrates include
– Small sugar molecules in soft drinks
• Monosaccharides & Disaccharides
– Long starch molecules in pasta and potatoes
• Polysaccharides
Monosaccharides
• Monosaccharides are simple sugars
– Glucose, found
in sports drinks
– Fructose, found
in fruit
• Honey contains
both glucose and
fructose
Glucose
Fructose
Isomers
Monosaccharides
• In aqueous solutions, monosaccharides form
rings
(b) Abbreviated ring
structure
Disaccharides
• A disaccharide is a double sugar
• Disaccharides are joined by the process of dehydration
synthesis
Glucose
Glucose
Maltose
Disaccharides
• The most common disaccharide is sucrose,
common table sugar
– It consists of a glucose
linked to a fructose
– Sucrose is extracted
from sugar cane and the
roots of sugar beets
Polysaccharides
– They are long chains of sugar units
– They are polymers of monosaccharides
Glucose
monomer
Starch granules in
potato tuber cells
(a) Starch
Glycogen
Granules
In muscle
tissue
(b) Glycogen
Cellulose fibril in
a plant cell wall
Cellulose molecules
(c) Cellulose
Polysaccharides
• Most animals cannot derive nutrition from
fiber
– How do grazing animals survive
on a diet of cellulose?
Proteins
• Proteins perform most of the tasks the body
needs to function
– They are the most elaborate of life’s molecules
MAJOR TYPES OF PROTEINS
Structural Proteins
Storage Proteins
Contractile Proteins
Transport Proteins
Enzymes
The Monomers: Amino Acids
• All proteins are constructed from a common
set of 20 kinds of amino acids
Amino Carboxyl
group
group
Side
group
Proteins as Polymers
• Cells link amino acids
together by
dehydration synthesis
– The resulting bond
between them is
called a peptide
bond
Carboxyl
group
Amino
group
Side
group
Side
group
Amino acid
Amino acid
Dehydration
synthesis
Side
group
Side
group
Peptide bond
Protein Structure
– The arrangement of
amino acids makes
each protein different
• Primary
structure
– The specific
sequence of amino
acids in a protein
5
1
15
10
30
35
20
25
45
40
50
55
65
60
70
85
80
75
95
90
100
110
105
115
120
125
129
Amino acid
Protein Structure
• A slight change in the primary structure of a protein
affects its ability to function
– The substitution of one amino acid for another in
hemoglobin causes sickle-cell disease
1
2
(b) Sickled red blood cell
6
7. . . 146
4
5
Normal hemoglobin
(a) Normal red blood cell
1
3
2
3
6
7. . . 146
4
5
Sickle-cell hemoglobin
Protein Structure
• Proteins have four levels of structure
Hydrogen bond
Pleated sheet
Polypeptide
(single subunit)
Amino acid
(a) Primary structure
Complete
protein,
with four
polypeptide
subunits
Hydrogen bond
Alpha helix
(b) Secondary
structure
(c) Tertiary
structure
(d) Quaternary structure
Nucleic Acids
● Include DNA and RNA
Information storage molecules
They provide the directions for building proteins
Gene
DNA
Nucleic acids
Amino acid
RNA
Protein
Nucleic Acids
●Nucleic acids are polymers of nucleotides
Nitrogenous base
(A,G,C, or T)
– DNA, deoxyribonucleic acid
– RNA, ribonucleic acid
Nitrogenous base
A, G, C, or U
Thymine (T)
Phosphate
group
Sugar
(deoxyribose)
Uracil U
Phosphate
Phosphate
group
Base
Sugar
Sugar ribose
Nucleic Acids
●Each DNA nucleotide has one of the following bases:
Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)
Adenine A
Guanine G
Thymine T
Cytosine C
Nucleic Acids
●Nucleic Acid Structure
Sugar-phosphate
backbone
Base
Nucleotide pair
Hydrogen
bond
Bases
a DNA strand
polynucleotide
b Double helix
two polynucleotide strands
Lipids
●Lipids are:
Neither macromolecules nor polymers
Hydrophobic, unable to mix with water
Oil (hydrophobic)
Vinegar (hydrophilic)
Figure 3.10
Lipids
●FATS
● Dietary fat consists largely of the molecule triglyceride
– A combination of glycerol and three fatty acids
Fatty acid
Glycerol
(a) A dehydration reaction linking a fatty acid to glycerol
(b) A fat molecule with a glycerol “head” and three
energy-rich hydrocarbon fatty acid “tails”
Lipids (Fats)
●Unsaturated fatty acids
– Have less than the maximum number of hydrogens
bonded to the carbons
●Saturated fatty acids
– Have the maximum number of hydrogens bonded to
the carbons
Lipids (Fats)
TYPES OF FATS
Saturated Fats
Unsaturated Fats
Margarine
INGREDIENTS: SOYBEAN OIL, FULLY HYDROGENATED
COTTONSEED OIL, PARTIALLY HYDROGENATED
COTTONSEED OIL AND SOYBEAN OILS, MONO AND
DIGLYCERIDES, TBHO AND CITRIC ACID
Plant oils
Trans fats
ANTIOXIDANTS
Omega-3 fats
Lipids
●STEROIDS
Steroids are very different from fats in structure and
function.
Cholesterol
Testosterone
A type of estrogen
Biological Molecules
Visual
Summary 3.2