Biomolecules and
Biofuels
Laura Penman
Q. Why Biofuel?
What are the sources of biofuel?
• A Biofuel can be any renewable organic
molecule that releases usable energy
– Renewable: able to be generated repeatedly
– Organic: based on carbon skeletons
» From living things or once-living things
Four different kinds of organic molecules
• Carbohydrates
– Sugar-based (starches, glycogen, cellulose)
• Proteins
– Amino acid based (actin, keratin, collagen)
• Lipids
– Don’t mix well with water (oils and fats)
• Nucleic Acids
– Nucleotide-based (DNA and RNA)
Molecules can be put together
OH
HO
H
O-H
O
Dehydration Synthesis!!
Molecules can also be broken down
O
H
O-H
OH
Hydrolysis
HO
Note that water (H20) is involved in both!
• Dehydration synthesis removes H+ and OH- from
two different molecules to synthesize (put
together) a polymer
• Hydrolysis uses a water molecule to split (lyse) a
big molecule into two smaller ones
Connections to biofuel
• Hydrolysis is often used to release energy
from molecules
(Dehydration synthesis is used to build complex
polymers)
Your body uses organic
molecules as fuel
Calorie : a measure of energy in
a molecule
• 9 calories /gram lipids
• 4 calories/gram carbohydrate
• 4 calories / gram protein
So do your automobile
engines
• Biodiesel
• Oil-based
• plant or animal sources
• Ethanol
• Sugar-based
• Plant sources
Q. What is “ethanol”?
• Aka. ethyl alcohol
• Clear, colorless liquid
• Flammable
Q. How is
alcohol/ethanol made?
• By fermenting sugars
– Fructose
– Maltose
– Sucrose
What do you suppose
“-ose” means?
Q. How does the
sugar get fermented?
• By yeast, when oxygen
isn’t present
BASIC ethanol production
Carbohydrate source  sugars  ethanol
The challenge
EASY
Been there, done that
Does ethanol production from
carbohydrates involve
Hydrolysis
or
Dehydration synthesis?
BASIC ethanol production
Carbohydrate source  sugars  ethanol
The challenge
EASY
Been there, done that
“Major players” in biofuel ethanol
(NOT grape juice)
• Corn sugars/starches
• PRO: fermentation technique is established
– Starchsugar ethanol
• CON: $ to plant each year, irrigate, fertilize
• Sugar cane
• PRO: fermentation technique is established
– Sugar ethanol
• CON: doesn’t grow in the USA
• Switchgrass and willow
• PRO: native perennial to most of USA, easy to grow
• CON: processing is not worked out yet
– Cellulose-->sugar?????
Which leads us to today’s lab…
• Switchgrass (Panicum virgatum) --a low-cost
and low-labor source of cellulose in this region
– Perennial (harvest biomass yearly)
– Minimal nutrient requirements
– Able to handle a range of water conditions
Cellulose is in the cell walls of each
plant cell
Cellulose Molecule
Cellulose fibers
Fiber
Microfibers
Cellulose +
Cellulose +
Plant cell
Hemicellulose +Hemicellulose
Lignin
Switchgrass
Cell wall
Switchgrass provides a great
source of biomass (potential fuel)
• BIG organic molecules (like cellulose) are
called polymers
– Made from small subunit molecules called
monomers
Cellulose structure
Cellulose is a chain molecule made of small units of glucose (sugar):
Choose one: Cellulose is a monomer or polymer?
Choose one: Glucose is a monomer or polymer?
glucose
A special chemical was found that breaks down
cellulose polymers into glucose!
AccelLerase
• If we maximize this breakdown process, we will
have plenty of glucose to ferment!
• Your challenges are :
– To determine what kind of molecule “accellerase” is
(Part 1)
– To determine the effect of pH on this process! (Part 2)
• Accellerase is an organic molecule
• You will learn which type in lab (Part II)
– Indicators change colors in the presence of certain
molecules
•
•
•
•
Benedicts turns blue-- if it is a sugar
Iodine turns black-- if it is a starch
Biurets turns purple-- if it is a protein
Sudan IV turns red-- if it is a lipid
• What kind of molecule is Accellerase?
Sugar
Carbohydrate
Test name
Color of negative
control
Material in
positive control
Color or positive
control
Color of
Accellerase after
test
Starch
Carbohydrate
Protein
Lipid
Maximizing “Accellerase”
• What can we control in order to get the most
“bang for our buck”?
– Prepare experiment to study two factors
• 1)
• 2)
pH
size of switchgrass material
Size of switchgrass material
• Your group will be assigned one of the
following types of switchgrass
– Cut switchgrass leaves
– Pelletized switchgrass leaves
– Powdered switchgrass leaves
Every group will
examine the effect of pH
on “accellerase” activity
• Treatment series 1 (Tubes 1, 2, 3, and 4)
– 4 tubes containing 15 ml of the following solutions
pH 3, pH 5, pH 7, pH 9
– Add 5 g switchgrass to each tube
– Add 0.5 ml Accellerase
• Treatment series 2 (Tubes 5, 6, 7, and 8)
– 4 tubes containing 15 ml of the following solutions
pH 3, pH 5, pH 7, pH 9
– Add 5 g switchgrass to each tube
– DO NOT add Accellerase
pH ___3____
Switchgrass +
Accellerase
Switchgrass
without
Accellerase
pH ___5____
pH ___7____
pH ____9___
ASSIGNMENT for next lab period:
• Complete questions in handout for part I
• Also form hypotheses regarding pH and
pretreatment of switchgrass
• Did accellerase increase glucose production?
• Were the effects of accellerase similar for all pH
levels?
• Which pH helped accellerase work the best?
Prepare a graph showing your results.
• Based on your graph, which pH range would you
want to test as you “iron out” the technique?
“Accellerase” & Cellulose breakdown
•Some enzymes are used by organisms to break down (digest) polymers
(Other enzymes are used by organisms to build polymers)
•Enzymes end with “-ase”
•Cellulase enzymes can break down cellulose into its sugar molecules.
Conversion of cellulose
Cellulose molecule
1- The enzyme recognizes the
cellulose molecule
2- The enzyme cuts the atomic
bond
3- One molecule of glucose is
released
4- The enzyme advances to the
other unit
The enzyme processes along the
cellulose molecule
Cellulase (enzyme)
The cellulose is converted into
fermentable sugars
Enzymes are proteins
The function of enzymes relies on their shape.
Denaturation: permanent loss of enzyme function by
permanently altering its shape
Temperature – too high
pH— too high or too low
Biomolecule Review
• Remember that
– Ethanol is “sugar-based”
– Biodiesel is “lipid-based”
Source for ethanol or biofuel?
Source for ethanol or biofuel?
Source for ethanol or biofuel?
Source for ethanol or biofuel?
Source for ethanol or biofuel?
Source for ethanol or biofuel?
Source for ethanol or biofuel?
Source for ethanol or biofuel?