Molecules of Life I
CHAPTER 3
Carbon/Organic Chemistry
• Bonding in hydrocarbons
• Functional groups
• Monomers and Polymers, Linking and Breaking
Carbohydrates
• Monosaccharides
• Disaccharides
• Polysaccharides
Lipids
• Fats and Oils
• Steroids
• Phospholipids
Relevance of Biomolecules in Everyday Life
completely
Organic Molecules
•
•
•
A cell is mostly water.
–
The rest of the cell consists mostly of carbon-based molecules.
–
Organic chemistry is the study of carbon compounds.
Carbon is a versatile atom.
–
It has four electrons in an outer shell that holds
eight.
–
Carbon can share its electrons with other atoms
to form up to four covalent bonds.
Carbon can use its bonds to:
–
Attach to other carbons.
–
Form an endless diversity of carbon skeletons.
Each Carbon Atom Makes Four Covalent Bonds to Other Atoms
Figure 3.2
Carbon Connects With Hydrogens to Form Hydrocarbons
Methane (CH4) is the simplest hydrocarbon
Figure 3.3
Other Hydrocarbons in Our Lives
Figure 3.4
Molecules of Life I
CHAPTER 3
Carbon/Organic Chemistry
• Bonding in hydrocarbons
• Functional groups
• Monomers and Polymers, Linking and Breaking
Carbohydrates
• Monosaccharides
• Disaccharides
• Polysaccharides
Lipids
• Fats and Oils
• Steroids
• Phospholipids
Structure Gives Rise to Function
• Each type of organic molecule has a unique threedimensional shape that defines its function in an
organism.
– The molecules of your body recognize one
another based on their shapes.
– Even slight differences in molecular arrangement
effects the chemical behavior of a molecule
– Certain groups of atoms confer chemical
reactivity to a molecule (functional groups)
Isomers
Functional Groups That Contribute to Molecular Behavior
Figure 3.5
Molecules of Life I
CHAPTER 3
Carbon/Organic Chemistry
• Bonding in hydrocarbons
• Functional groups
• Monomers and Polymers, Linking and Breaking
Carbohydrates
• Monosaccharides
• Disaccharides
• Polysaccharides
Lipids
• Fats and Oils
• Steroids
• Phospholipids
Giant Molecules from Smaller Building Blocks
• On a molecular scale, many of life’s molecules are
gigantic.
– Biologists call them macromolecules.
– Examples: DNA, carbohydrates
• Most macromolecules are polymers.
– Polymers are made by stringing together many
smaller molecules called monomers.
– Cells link monomers by dehydration reactions.
monomers
polymer
Dehydration/Condensation Synthesis of a Polymer
Figure 3.6a
Hydrolytic Breakdown of a Polymer
Figure 3.6b
Biological Molecules
• There are four categories of large molecules
in cells:
– Carbohydrates
– Lipids
– Proteins
– Nucleic acids
Molecules of Life I
CHAPTER 3
Carbon/Organic Chemistry
• Bonding in hydrocarbons
• Functional groups
• Monomers and Polymers, Linking and Breaking
Carbohydrates
• Monosaccharides
• Disaccharides
• Polysaccharides
Lipids
• Fats and Oils
• Steroids
• Phospholipids
Carbohydrates
• Carbohydrates are composed of:
– Simple sugars (monosaccharides) found in table
sugar, fruit, and soft drinks.
– Complex sugars (polysaccharides) found in
pasta and potatoes as well as the cells of plants
Simple Sugars: Monosaccharides
• Monosaccharides are simple sugars.
– Glucose is found in sports drinks.
– Fructose is found in fruit.
• Honey contains both glucose and fructose.
Glucose and Fructose are Structural Isomers
Hydroxyl
groups
make
these
sugars
polar and
water
soluble
Carbonyl
functional
groups
makes
these
sugars
reactive
(can lose
electrons)
Same molecular formula but different structural formulas
Simple Sugars Usually “Round up” into Rings
Glucose
Fructose
Straight chain form
Ring form
Disaccharides
• A disaccharide is a
double sugar.
– It is constructed from
two monosaccharides.
• Disaccharides are joined
through a dehydration
reaction.
Disaccharides
Lactose is a disaccharide that some people cannot
digest as adults
Figure 3.11
Table Sugar (Sucrose) is a Disaccharide
Polysaccharides
• Complex carbohydrates are called polysaccharides.
– They are long chains of sugar units.
– They are polymers of monosaccharides.
• Polysaccharides can be classified by function
– Energy storage polysaccharides
– Structural support polysaccharides
Polysaccharides
Three Polysaccharides
Energy storage
Energy storage
Structural support in plants
Figure 3.13
Cellulose Cannot Be Broken into Glucose
Monosaccharides By Mammals
Plant-eaters have resident bacteria and protozoa that break the
cellulose into glucose within their digestive system
Molecules of Life I
CHAPTER 3
Carbon/Organic Chemistry
• Bonding in hydrocarbons
• Functional groups
• Monomers and Polymers, Linking and Breaking
Carbohydrates
• Monosaccharides
• Disaccharides
• Polysaccharides
Lipids
• Fats and Oils
• Steroids
• Phospholipids
Lipids
• Lipids are not water soluble (hydrophobic)
– Lipids are mostly composed of hydrocarbon
chains or rings
– They do not mix with water.
• Important lipid polymers that we will study are:
– Fats and Oils
– Phospholipids
– Steroids
Fats and Oils (Triglycerides)
• Fats perform essential functions in the human
body:
– Energy storage
– Cushioning
– Insulation
• A fat or oil consists of a four part chain of
hydrocarbons (a triglyceride)
– Triglyceride is a combination of glycerol and
three fatty acids.
A Fat or Oil is Made From Three Fatty Acids and One Glycerol
Dehydration reactions
Fats
Saturated and Unsaturated Fats (Triglycerides)
•
•
Unsaturated fatty acids (One or more C=C bonds)
–
Have less than the maximum number of hydrogens bonded to the
carbons.
–
Tend to be solid at room temperature, e.g.. butter
Saturated fatty acids (Only C-C bonds)
–
Have the maximum number of hydrogens bonded to the carbons.
–
Tend to be liquid at room temperature, e.g. corn oil
Healthy Triglycerides
• Not all fats are unhealthy.
– Some fats perform important functions in the body and are
essential to a healthy diet.
– Many unsaturated fats and cis-fats are good for you
Steroids
• Steroids are very different from fats in structure
and function.
– The carbon skeleton is bent to form four fused
rings.
• Cholesterol is the “base steroid” from which your
body produces other steroids.
– Example: sex hormones
Steroids Consist of Four Joined Rings
Biological role: Helps
keep cell wrappers
(membranes) fluid
and flexible
Biological
role: Act as
chemical
messengers
(hormones) to
stimulate
certain body
parts
Phospholipids: Barrier-forming molecules
Phospholipids
organize into
double-layered
spheres in water
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
Molecules of Life I
CHAPTER 3
Carbon/Organic Chemistry
• Bonding in hydrocarbons
• Functional groups
• Monomers and Polymers, Linking and Breaking
Carbohydrates
• Monosaccharides
• Disaccharides
• Polysaccharides
Lipids
• Fats and Oils
• Steroids
• Phospholipids
Proteins and Nucleic Acids
will be discussed next time