How To Make Biological Molecules
Adapted from Kim Fogia and David Knuffke work
How to build a polymer
• Synthesis
– joins monomers by “taking” H2O out
• one monomer donates OH–
• other monomer donates H+
• together these form H2O
H 2O
– requires energy & enzymes
HO
H
Dehydration synthesis
HO
H
enzyme
Condensation reaction
HO
H
How to break down a polymer
• Digestion
– use H2O to breakdown polymers
• reverse of dehydration synthesis
• cleave off one monomer at a time
• H2O is split into H+ and OH–
– H+ & OH– attach to ends
– requires enzymes
– releases energy
HO
H2O
enzyme
H
Hydrolysis
Digestion
HO
H
HO
H
Dehydration and Hydrolysis
• http://www.youtube.com/watch?v=b7TdWLN
hMtM&feature=related
CH2OH
H
O
H
OH
H
H
OH
HO
H
OH
Carbohydrates
energy
molecules
Carbohydrates
• Carbohydrates are composed of C, H, O
• Ratio of 1:2:1
(CH2O)x
• Function:
– energy
– energy storage
– raw materials
– structural materials
• Monomer: sugars
C6H12O6
• ex: sugars,
starch, cellulose
sugar sugar sugar sugar sugar sugar sugar
Sugars
• Most names for sugars end in -ose
• Classified by number of carbons
– 6C = hexose (glucose)
– 5C = pentose (ribose)
– 3C = triose (glyceraldehyde)
CH2OH
H
O
H
OH
6H
HO
H
OH
Glucose
H
CH2OH
OH
C
O
H
HO
H
5
OH
O
H
HO
H
Ribose
H
H
H
C
OH
C
3OH
H
Glyceraldehyde
Functional groups determine function
carbonyl
aldehyde
carbonyl
ketone
Sugar structure
5C & 6C sugars form rings in solution
Carbons are numbered
Numbered carbons
C 6'
5' C
O
4' C
C1'
energy stored in C-C bonds
C3'
C2'
Simple & complex sugars
CH2OH
H
• Monosaccharides
– simple 1 monomer sugars
– glucose
• Disaccharides
– 2 monomers
– sucrose
• Polysaccharides
– large polymers
– starch
O
H
OH
H
H
OH
HO
Glucose
H
OH
Glucose vs. Fructose vs. Galactose
Isomers?
main source of energy
• Formula:
C6H12O6
• Sources: nectar,
sap, blood
•Formula:
C6H12O6
•Sources:
Fruits
• Formula:
C6H12O6
• Sources:
Milk
Types of Isomers
(examples can be found on page 35)
• Stereoisomers: differ in 3D orientation
• Structural: same chemical formula but differ in the
order they are covalently bonded
• Geometric (diastereomers): have same chemical
formula but differ in the way they are arranged on
either side of double bond or ring.
• Optical: (enantiomers):same chemical formula but
the arrangement around the Carbon that has four
different groups around it (mirror images)
Building sugars
• Dehydration synthesis
monosaccharides
|
glucose
H2O
|
glucose
disaccharide
|
maltose
glycosidic linkage
Building sugars
• Dehydration synthesis
monosaccharides
|
glucose
H2O
|
fructose
disaccharide
|
sucrose
(table sugar)
Building sugars
• Dehydration synthesis
monosaccharides
|
glucose
H2O
|
galactose
disaccharide
|
lactose
glycosidic linkage
Polysaccharides
• Polymers of sugars
– costs little energy to build
– easily reversible = release energy
• Function:
– energy storage
• starch (plants)
• glycogen (animals)
– in liver & muscles
– structure
• cellulose (plants)
• chitin (arthropods & fungi)
Linear vs. branched polysaccharides
slow release
starch
(plant)
Straight chain:
amylose
Branched:
amylopectin
http://cnx.org/content/m46008/latest/?collection=col11496/latest
energy
storage
glycogen
(animal)
fast release
Cellulose not
digestible by us
Bacteria cell wall
Fungi ,arthropods
http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/imag
es/u1fig8b.jpg
http://academic.brooklyn.cuny.edu/biology/bio4fv/page/chitin.jpg
Polysaccharide diversity
• Molecular structure determines function
in starch
in cellulose
isomers of glucose
 structure determines function…

Digesting starch vs. cellulose
starch
easy to
digest
enzyme
cellulose
hard to
digest
enzyme
Chitin, a different structural
polysaccharide
H
OH
CH2OH
O OH
H
OH H
H
H
NH
C
O
CH3
(a) The structure of the
chitin monomer.
(b) Chitin forms the exoskeleton of arthropods. This
cicada is molting, shedding its
old exoskeleton and emerging
in adult form. It is also found in
Fungal Cell Walls.
(c) Chitin is used to make a
strong and flexible surgical
thread that decomposes after
the wound or incision heals.
Cellulose
• Most abundant organic
compound on Earth
– herbivores have evolved a mechanism to digest
cellulose
– most carnivores have not
• that’s why they
eat meat to get
their energy &
nutrients
• cellulose = undigestible roughage
Cow
can digest cellulose well;
no need to eat other sugars
Gorilla
can’t digest cellulose well; must
add another sugar source, like
fruit to diet
Helpful bacteria
• How can herbivores digest cellulose so well?
– BACTERIA live in their digestive systems & help digest celluloserich (grass) meals
Ruminants- 4 compartments
Longer
digestion
process
Ruminant: any even-toed,
hoofed mammal of the suborder
Ruminantia, being comprised of
cloven-hoofed, cud-chewing
quadrupeds, and including,
besides domestic cattle, bison,
buffalo, deer, antelopes, giraffes,
camels, and chevrotains.
Dictionary.com
• What elements are Carbohydrates composed
of?
• What are the functions of Carbohydrates?
• How are carbohydrates broken down in our
bodies?
2. Which of the following is a polymer?
A. Simple sugar (aka monosaccharide)
B. Carbon atoms
C. Glucose
D. Cellulose
E. deoxyribose
3. Starch and Glycogen both
I. Serve as energy storage for
organisms
II. Provide structure and support
III. Are structural isomers of glucose
A. I only
B. II only
C. I and II only
D. I and III only
E. I, II, and III