CHPTR 9: CELLULAR RESPIRATION & FERMENTATION

9.1: CELLULAR RESPIRATION: AN OVERVIEW

Key Questions Where do organisms get energy? What is cellular Respiration? What is the relationship between photosynthesis

and cellular respiration Vocab:

Calorie Cellular Respiration Aerobic Anaerobic

WHERE DO WE GET ENERGY?

Autotrophs vs. Heterotrophs

Autotroph: Makes own food through Photosynthesis

Heterotroph: rely on other organisms for food

WHY IS FOOD GOOD? HOW MUCH ENERGY IS STORED IN FOOD?

When we digest food…we are breaking the chemical bonds with the molecules = Calories!

Calorie is the measure of energy within food Technically: A calorie is the amount of energy needed

to raise the temperature of 1 gram of water 1 degree celsius. On labels, the Cal # is a kilocalorie / 1000calories

All macromolecules can be used for fuels! However, the value depends on its structure

(pg 45-48) 1 gram of glucose= 3811 calories of heat (3.8 C) 1 gram of beef fat = 8893 calories of heat (8.9 C) Protein = 4 Carbo = 7 Fat = 9

CELLULAR RESPIRATION

The process that releases energy from food in the presence of O2.

Example: 6O2+C6H12O66CO2+6H20+Energy Oxygen+glucoseCarbon Dioxide+water+Energy

STAGES OF CELLULAR RESPIRATION

1. Glycolysis: poor yield of energy1. Anaerobic: without O22. Aerobic: with O2

2. *Krebs Cycle: Better yield3. *Electron chain: High yield of energy

*happens within Mitochondrion

PHOTO VS. RESPIRATION

Opposite processes feed each other

REVIEW

Why do all organisms need food?

Why do macromolecules differ in the amount of energy produced?

Cellular respiration?

How are photosynthesis and cellular respiration considered oposite?

9.2 THE PROCESS OF CELLULAR RESPIRATION

Key Questions: What happens during the process of glycolysis? What happens during the krebs cycle? How does the electron transport chain use high-

energy electrons from glycolysis and the krebs cycle

How much energy does cellular respiration generate?

Vocab: Glycolysis NAD+ Krebs Cycle Matrix

GLYCOLYSIS: Definition: First step of cellular respiration “sugar

breaking” Where: in the cytoplasm! During Glycolysis: 1 molecule of Glucose (6-carbon

compound) is transformed into 2 molecules of Pyruvic acid (a 3-carbon compound)

The end result of Glycolysis is: 2 ATP 2 NADH 2 Pyruvic acid

ATP: unit of energy NAD+: Electron carrier (nicotinamide adenine dinucleotide)

GLYCOLYSIS CONTINUED…

Key points:2 ATP to start

produces 4 ATP

Net gain of only 2ATP

What happens to the NADH?

http://www.youtube.com/watch?v=x-stLxqPt6E

Glycolysis:ATP: 2

NADH: 2

GLYCOLYSIS CONTINUED…

Advantages: Speed Can repeat quickly Does not require O2

Disadvantages: Needs ATP to get ATP! Small yield of ATP

KREBS CYCLE

Definition: second stage of respiration Where: in the Matrix of the Mitochondria

Matrix: innermost compartment of the mitochondrion and the site of the kreb cycle reactions.

What happens: Pyruvic acid is broken down into carbon dioxide in a series of energy extracting reactions.

**because Citric acid is the first compound formed, the kreb is also called the “citric acid cycle.”

KREBS CYCLE…CONTINUED

The process:1. Each Pyruvic acid (2) enters Matrix

2. Releases NADH!

3. Converts to Acetyl-CoA

4. Enters Krebs, becoming citric acid (6-carbon)

5. O2 removed carbon through Co2 (5-carbon)

6. NADH!

7. Another CO2 released (4-carbon)

8. NADH!

9. ATP!!!!

10. FAD

11. NADH!!!

12. This happened again with second pyruvic Acid

http://www.youtube.com/watch?v=aCypoN3X7KQ

Krebs cycle:ATP=2

NADH= 8FADH=2CO2=4

1

2

10

11

3

4

6

5

8

7

9

ELECTRON TRANSPORT CHAIN

Last step of cellular respiration

The electron transport chain uses the high-energy electrons from glycolysis and the krebs cycle to convert ADP to ATP

http://www.youtube.com/watch?v=Idy2XAlZIVA

ELECTRON TRANSPORT CHAIN1. NADH and FADH pass their pair of high-energy electrons through the chain

2. High-energy electrons are passed from one carrier to the next

3. Transferring of HE electrons through the carriers shifts Hions into the intermembrane space

4. O2 is final acceptor forming Water

5. Build up H+ outside membrane

6. Pressure forces H+ through ATP synthase

7. Formation of ATP

1

5

4

2

3

6

7

Each pair of electrons

yield 3 ATP

Electron chain

=32

ATP!!!

THE TOTALS…

For each Glucose Molecule:Glycolysis = 2 ATP

Krebs = 2 ATP

ETC = 32 ATP

36 ATP per each molecule of Glucose!!

9.2 REVIEW

1. What are the products of glycolysis?

2. What happens to Pyruvic acid in the Krebs?

3. What are the products of the Krebs?

4. How does the ETC use the high-energy electrons from glycolysis and krebs?

5. How does the cell memebrane use the H+ build up to create ATP?

6. How many molecules of ATP are produced in the entire breakdown of glucose?

LESSON OVERVIEW9.3 Fermentation

THINK ABOUT IT

We use oxygen to release chemical energy from the food we eat, but what if oxygen is not around?

Is there a pathway that allows cells to extract energy from food in the absence of oxygen?

http://www.5min.com/Video/How-Fermentation-Works-83226972

FERMENTATION

How do organisms generate energy when oxygen is not available?

FERMENTATION

How do organisms generate energy when oxygen is not available?

In the absence of oxygen, fermentation releases energy from food

molecules by producing ATP.

FERMENTATION

Fermentation is a process by which energy can be released from food molecules in the absence of oxygen. Fermentation occurs in the cytoplasm of cells.

FERMENTATION

Under anaerobic conditions, fermentation follows glycolysis. During fermentation, cells convert NADH produced by glycolysis back into the electron carrier NAD+, which allows glycolysis to continue producing ATP.

ALCOHOLIC FERMENTATION

Yeast and a few other microorganisms use alcoholic fermentation that produces ethyl alcohol and carbon dioxide.

This process is used to produce alcoholic beverages

and causes bread dough to rise.

ALCOHOLIC FERMENTATION

Chemical equation:

Pyruvic acid + NADH Alcohol + CO2 + NAD+

LACTIC ACID FERMENTATION

Most organisms, including humans, carry out fermentation using a chemical reaction that converts pyruvic acid to lactic acid.

Chemical equation:

Pyruvic acid + NADH Lactic acid + NAD+

ENERGY AND EXERCISE

How does the body produce ATP during different stages of exercise?

ENERGY AND EXERCISE

How does the body produce ATP during different stages of exercise?

For short, quick bursts of energy, the body uses ATP already in muscles as

well as ATP made by lactic acid fermentation.

For exercise longer than about 90 seconds, cellular respiration is the only

way to continue generating a supply of ATP.

QUICK ENERGY

Cells normally contain small amounts of ATP produced during cellular respiration, enough for a few seconds of intense activity.

Lactic acid fermentation can supply enough ATP to last about 90 seconds. However, extra oxygen is required to get rid of the lactic acid produced. Following intense exercise, a person will huff and puff for several minutes in order to pay back the built-up “oxygen debt” and clear the lactic acid from the body.

LONG-TERM ENERGY

For intense exercise lasting longer than 90 seconds, cellular respiration is required to continue production of ATP.

Cellular respiration releases energy more slowly than fermentation does.

The body stores energy in the form of the carbohydrate glycogen. These glycogen stores are enough to last for 15 to 20 minutes of activity. After that, the body begins to break down other stored molecules, including fats, for energy.

LONG-TERM ENERGY

Hibernating animals like this brown bear rely on stored fat for energy when they sleep through the winter.