Giant Molecules from Smaller Building Blocks Cells link monomers ...

Chapter 5-The Molecules of Life-Large Biological Molecules
Giant Molecules from Smaller Building Blocks
In biology, large molecules such as proteins, DNA, and some
carbohydrates (polysaccharides) are called macromolecules.
Polymer
Cells link monomers together to form polymers by a process
called dehydration synthesis.
Organisms not only form macromolecules, but they also break them down.
This process is called hydrolysis (the reverse of
dehydation synthesis).
Biological Molecules
Carbohydrates, Lipids, Proteins, and Nucleic Acids
Carbohydrates
Monosaccharides ( Mono = 1) (Sacchar = sugar)
Monosaccharides have the formula in multiples of
the chemical formula CH 2 O.
Triose sugars
(C 3 H 6 O 3 )
Pentose sugars
(C 5 H 10 O 5 )
Hexose sugars
(C 5 H 12 O 6 )
Glyceraldehyde
Ribose
Glucose
Galactose
Dihydroxyacetone
Ribulose
Fructose

Carbohydrates
Monosaccharides ( Mono = 1) (Sacchar = sugar)
Disaccharides ( Di = 2) (Sacchar = sugar)
Dehydration
reaction in the
synthesis of maltose
Glucose
Glucose
Maltose
Monomer + Monomer in the process
of dehydration synthesis.
Dehydration
reaction in the
synthesis of sucrose
Glucose
Fructose
Sucrose
Do you know what 2 plants are used in the
U.S. to produce sucrose, or table sugar?
Polysaccharides (poly=many) (Sacchar= sugar)
Complex carbohydrates
Long chains of sugar units
Examples of Polysaccharides
Chloroplast
Starch
Starch
Found in roots and other plant organs.
Glycogen granules
Mitochondria
Amylose
Amylopectin
Glycogen
Animals store excess sugar in this polysaccharide.
Glycogen is broken down in our bodies or hydrolyzed to
release glucose when it is needed.

Cellulose
Cellulose is the most abundant organic compound on Earth.
Cellulose is also a polymer of glucose units, but
the glucose monomers are linked together in different
orientation.
a Glucose
a and b glucose ring structures
b Glucose
Cell walls
Cellulose microfibrils
in a plant cell wall
Microfibril
Starch: 1–4 linkage of a glucose monomers.
Cellulose: 1–4 linkage of b glucose monomers.
b Glucose
monomer
Cellulose
molecules
•Enzymes that digest starch by hydrolyzing alpha linkages can’t
hydrolyze beta linkages in cellulose
Carbohydrates are hydrophilic (hydro=water; philic=loving) biological molecules.
In contrast to carbohydrates and other biological molecules,lipids do not mix with water.
Lipids are hydrophobic (hydro = water) (phobic=fearing)
Lipids
Examples of lipids are:
Fats
Dietary fats consist of the molecule triglyceride.
The triglyceride is made of a molecule of glycerol joined with
3 molecules of fatty acids.
Like the hydrocarbons in gasoline, the long hydrocarbon
chain of the fatty acid in a triglyceride stores a large
amount of energy.
A pound of fat packs more than twice as much energy as
a pound of carbohydrates.

“Saturated” fats versus “unsaturated” fats
he fatty acid is said to be unsaturated because it has less
han the maximum number of hydrogens at the location of
he double bond.
Fatty acids are saturated because they are bonded to
the maximum number of hydrogen atoms.
Saturated fats
Stearic acid
- Solid at room temperature
Saturated fat and fatty acid.
Unsaturated fats
- Usually liquid at room temperature
Unsaturated fat and fatty acid.
Phospholipids
•In a phospholipid, two fatty acids and a phosphate group
are attached to glycerol
cis double bond
causes bending
Choline
Phosphate
Glycerol
When phospholipids are added to water, they selfassemble
into a bilayer, with the hydrophobic tails
pointing toward the interior
Fatty acids
The structure of phospholipids results in a bilayer
arrangement found in cell membranes
WATER
Hydrophilic
head
Hydrophobic
tails
WATER

Steroids
Steroids are very different from fats in structure and function.
•Cholesterol, an important steroid, is a
component in animal cell membranes
Chapter 5-The Molecules of Life-Large Biological Molecules
-Know the four biological molecules: carbohydrates, lipids, proteins, and nucleic acids
-Know terms: macromolecule, polymer, monomer, dehydration synthesis, hydrolysis
-Know different carbohydrates and recognize examples of each:
monosaccharide, disaccharide, and polysaccharide
-Recognize examples and functions of three types of polysaccharides:
starch, glycogen, and cellulose
-Recognize the difference of two ring forms for glucose: alpha () and beta (b)
-Understand hydrophilic vs. hydrophobic
-Know examples of hydrophobic and hydrophilic biomolecules
-Understand the characteristics of a lipid
-Know terms and structure-fat, oil, triglyceride, glycerol
-Understand saturated vs. unsaturated and know examples of each
-Understand the structure of a steroid