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

Dehydration Synthesis!!

OH HO

O

O-HH

Molecules can also be broken down

O

OH HO

O-HH

Hydrolysis

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– SucroseWhat 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

EASYBeen there, done that

The challenge

Does ethanol production from carbohydrates involve

Hydrolysis or

Dehydration synthesis?

BASIC ethanol production

Carbohydrate source sugars ethanol

EASYBeen there, done that

The challenge

“Major players” in biofuel ethanol(NOT grape juice)

• Corn sugars/starches• PRO: fermentation technique is established

– Starchsugar 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

Plant cell

Cell wall

Cellulose fibers

Fiber

Cellulose +

Hemicellulose +

Lignin

Microfibers

Cellulose +

Hemicellulose

Cellulose Molecule

Switchgrass

Cellulose is in the cell walls of each plant cell

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

glucose

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?

A special chemical was found that breaks down cellulose polymers into glucose!

• 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

• 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

StarchCarbohydrate

Protein Lipid

Test name

Color of negative controlMaterial in positive control

Color or positive controlColor of Accellerase after test

Maximizing “Accellerase”

• What can we control in order to get the most “bang for our buck”?

– Prepare experiment to study two factors• 1) pH • 2) 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____ pH ___5____ pH ___7____ pH ____9___Switchgrass + Accellerase

Switchgrass without Accellerase

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

Cellulase (enzyme)

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

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 highpH— 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?