FERMENTATION AND

CELLULAR RESPIRATION

A WAY TO OBTAIN ENERGYLICEO SCIENTIFICO «NICCOLO’ COPERNICO»

PROF. ANTONIO ROVELLI -2017

ENERGY FROM FOOD

EVERY CHEMICAL BONDS CONTAIN ENERGY.

ENERGY IS RELEASED WHEN CHEMICAL BONDS ARE BROKEN.

FOOD MOLECULES CONTAIN USEFUL ENERGY THAT WE CAN OBTAIN WHEN THEY ARE DIGESTED

(= DIVIDED IN SMALLER MOLECULES)

IF OXYGEN IS AVAILABLE, ENERGY IS PRODUCED BY CELLULAR RESPIRATION BUT IN THE ABSENCE

OF OXYGEN CELLS USE FERMENTATION.

CELLULAR RESPIRATION AND FERMENTATION PRODUCE ATP.

WHAT’S ATP (ADENOSINE TRIPHOSPHATE)?

ATP IS AN ENERGETICS MOLECULE FORMED BY:

* ADENINE ( NITROGENOUS BASE)

* RIBOSE (SUGAR)

* 3 PHOSPHATE GROUPS

FERMENTATION

* IS THE PROCESS THAT RELEASES ENERGY

FROM FOOD (SUCH AS GLUCOSE) IN THE

ABSENCE OF OXIGEN.

* GLUCOSE IS CONVERTED IN PIRUVIC

ACID AND THAN IN:

- ETHYL ALCOHOL (ALCOHOLIC FERMENTATION)

- LACITC ACID (LACTIC FERMENTATION)

ALCOHOLIC FERMENTATION

ACID LACTIC FERMENTATION

COMPARISONBETWEEN

ALCOHOLICAND

ACID LACTICFERMENTATION

LAB IN PAIR!

1. LABEL TWO TEST TUBES A AND B

2. PUT 10 ML OF WATER AND A FEW DROPS OF BROMTHYMOL BLUE SOLUTION IN EACH TEST TUBE.

3. YOUR PARTNER WILL TIME YOU DURING THIS STEP. WHEN YOUR PARTNER SAYS «GO», SLOWLY BLOW AIR THROUGH A STRAW

INTO THE BOTTOM OF TEST TUBE A. CAUTION: DON’T INHALE THROUGH THE STRAW.

4. WHEN THE SOLUTION CHANGES COLOUR, YOUR PARTNER SAY «STOP» AND THEN RECORD HOW LONG THE COLOR CHANGE

TOOK.

5. JOG IN PLACE FOR TWO MINUTES.

6. REPEAT STEPS 3-4 USING TEST TUBE B.

7. TRADE ROLES WITH YOUR PARTNER. REPEAT STEPS 1-6.

LAB IN GROUP!

The purpose of any leavener is to produce the gas that makes bread rise. Yeast

does this by feeding on the sugars in flour, and expelling carbon dioxide in the

process.

While there are about 160 known species of yeast, Saccharomyces cerevisiae,

commonly known as baker's yeast, is the one most often used in the kitchen.

Yeast is tiny: Just one gram holds about 25 billion cells. That amount of fungi can

churn out a significant amount of carbon dioxide, provided it has the simple

sugars it uses as food. Fortunately, yeast can use its own enzymes to break down

more complex sugars—like the granulated sugar in the activity below—into a form

that it can consume.

Make a yeast-air balloon to get a better idea of what yeast can do.

WHAT DO I NEED?• 1 packet of active dry yeast• 1 cup very warm water• 2 tablespoons sugar

• a large rubber balloon• a small empty water bottle

WHAT DO I DO?1. Stretch out the balloon by blowing it up repeatedly, and then lay it aside.

2. Once the yeast and sugar have dissolved, put the mixture into the bottle.

3. Attach the balloon to the mouth of the bottle, and set both aside.

4. After several minutes, you’ll notice the balloon standing upright.

WHAT’S GOING ON?

As the yeast feeds on the sugar, it produces carbon dioxide. With no place to go but up, this

gas slowly fills the balloon.

A very similar process happens as bread rises. Carbon dioxide from yeast fills thousands ofballoonlike bubbles in the dough. Once the bread has baked, this is what gives the loaf itsairy texture.

WHAT ELSE CAN I TRY?

Try the same experiment, but this time use about a tablespoon of baking powder instead

of yeast, and leave out the sugar. What differences do you notice? Which leavener takes

longer to fill up the balloon?

Also, try the same experiment using hotter and colder water. Use a thermometer tomeasure the temperature of the water. At what temperature is the yeast most active?

CELLULAR RESPIRATION

IS THE PROCESS THAT RELEASE ENERGY FROM FOOD IN THE PRESENCE OF OXYGEN.

CELLULAR RESPIRATION INVOLVES DOZENS OF SEPARATE REACTIONS THAT WE CAN RESUME AS YOU SEE IN THE TABLE.

MITOCHONDRIAL STRUCTURE

QUESTION TIME

1. HOW MANY CARBON ATOMS ARE THERE IN GLUCOSE?

2. HOW MANY CARBON ATOMS ARE THERE IN EACH MOLECULE OF PIRUVIC ACID?

3. WHAT ARE THE PRODUCT OF GLYCOLYSIS?

4. WHERE DO THESE PRODUCTS GO?

5. WHICH STAGE(S) OF CELLULAR RESPIRATION OCCURS IN MITOCHONDRION?

6. HOW MANY MOLECULES OF ATP WE FIND IN FERMENTATION AND CELLULAR RESPIRATION?

7. WHAT IS THE MOST USEFUL OF THESE PROCESSES? WHY?

YOU ARE WHAT

YOU EAT

- ORGANISMS GET ENERGY FROM THE FOOD THEY EAT, BUT THE ENERGY CONTAINED IN FOODS VARIES GREATLY.

- MOST FOODS CONTAIN A COMBINATION OF CARBOHYDRATES, FATS AND PROTEINS.

- ONE GRAM OF CARBOHYDRATES OR PROTEINCONTAINS ROUGHLY 4 KCAL;

- ONE GRAM OF FATS CONTAINS 9 KCAL.

ANSWER THE QUESTIONS

1. PER SERVING, WHICH OF THE FOODS INCLUDED IN THE TABLE HAS MOST PROTEIN?

2. WHICH HAS THE MOST CARBOHYDRATES?

3. WHICH HAS THE MOST FAT?

COMPOSITION OF SOME COMMON FOODS

FOOD PROTEIN (g) CARBOHYDRATE (g) FAT (g)

Apple, 1 medium 0 22 0

Bacon, 2 slices 5 0 6

Chocolate, 1 bar 3 23 13

Eggs, 2 whole 12 0 9

2% milk, 1 cup 8 12 5

Potato chips, 15 chips 2 14 10

Skinless roasted turkey, 3 slices 11 3 1

4. APPROXIMATELY HOW MANY MORE KCAL ARE THERE IN 2 SLICES OF BACON THAN IN 3 SLICES OF ROASTED TURKEY?

WHY IS THERE A DIFFERENCE?

5. WALKING AT A MODERATE PACE CONSUMES AROUND 300 KCAL PER HOUR. AT THAT RATE, HOW MANY MINUTES

WOULD YOU HAVE TO WALK TO BURN THE KCAL IN ONE CHOCOLATE BAR?

COMPOSITION OF SOME COMMON FOODS

FOOD PROTEIN (g) CARBOHYDRATE (g) FAT (g)

Apple, 1 medium 0 22 0

Bacon, 2 slices 5 0 6

Chocolate, 1 bar 3 23 13

Eggs, 2 whole 12 0 9

2% milk, 1 cup 8 12 5

Potato chips, 15 chips 2 14 10

Skinless roasted turkey, 3 slices 11 3 1