CELLULAR RESPIRATION

CHAPTER 9

9-1 CHEMICAL PATHWAYS CHEMICAL ENERGY and FOOD

3811 calories of heat energy are produced per gram of glucose burned.

This is quite a lot of energy.

1 CALORIE = amount of energy needed to raise the temperature of 1 gram of water by 1 degree C.

Chemical Energy and Food

Food labels display the number of Calories and other nutritional information about a particular product.

These Calories (CAPITAL C) are actually kilocalories.

9-1 How much energy is in food?

when glucose is broken down completely in the presence of oxygen, then water and carbon dioxide are produced

Glycolysis is a series of enzymes catalyzes chemical reactions that change glucose one step at a time into different molecules

One molecule of glucose is broken in half producing two molecules of pyruvic acid

Pyruvic Acid is a 3-C compound

Chemical Energy and Food

Also called “sugar breaking”

occurs in the cytoplasm and does not need oxygen

Glycolysis only releases a small amount of energy.

Let’s find out how our cells can produce the large amounts of energy we require to perform our everyday functions.

SECTION 9-1: AN OVERVIEW of Cellular Respiration

When oxygen is present, the products of glycolysis enter the KREBS CYCLE and the ELECTRON TRANSPORT CHAIN.

This process is called CELLULAR RESPIRATION

GLYCOLYSIS

Process in which one molecule of glucose is broken in half producing two molecules of pyruvic acid.◦ Pyruvic Acid is a 3-C compund.

Where does the need energy in Glycolysis?To split the Glucose molecule.

Cell spends 2 ATP to begin process.Makes a TOTAL of 4 ATP NET GAIN = 2 ATP

What is the electron carrier in Glycolysis?

Glycolysis and NADH Production

NAD+ is the electron carrier.◦Nicotinamide adenine dinucleotide

4 HEe- are removed and passed to NAD+

Each NAD+ accepts 2 HEe- NADH

NAD+ helps pass energy from glucose to other cellular pathways.

Energy yield is only 2 ATP but the cell can make thousands of ATP in a short time.

FERMENTATIONWhy is this a problem for the cell?NAD+ is limited and they quickly fill up with e-

NAD+ is required to continue Glycolysis.

FERMENTATION releases energy from food molecules in the absence of oxygen.

Cells convert NADH back to NAD+Passes electrons back to Pyruvic AcidTWO TYPESAlcoholic and Lactic Acid

What does anaerobic mean?

Question of the DAY NOV 12

What are the reactants of fermentation?A. ADP and NADHB. Glucose and NADHC. Pyruvic Acid and Carbon DioxideD. Pyruvic Acid and NADH

DO NOW Nov 12

Why is NAD+ essential to a cell’s ability to produce ATP?

ANSWER

It transports energy from glucose to other pathways.

FERMENTATION

ALCOHOLIC LACTIC ACID

Yeast and microorganisms

Pyruvic acid + NADH yields

Ethyl Alcohol + Carbon Dioxide + NAD+

Why does bread dough rise?

Performed in most cells

Pyruvic acid + NADH yields

Lactic Acid + NAD+

Why do your muscles burn when engaging in strenuous activity?

REVIEW OF GLYCOLYSIS

What are the advantages of GLYCOLYSIS?

Are there any disadvantages to GLYCOLYSIS?

9-2: KREBS CYCLE and ETC

DRAW Figure 9-6 in your NOTESLabel all the parts and write down the STEPS

ANSWER the following Questions.Write down the question and the answer.1. Where does the KREBS CYCLE take place?2. How many ATP molecules are generated in one turn

of the cycle?3. How many ATP are generated per one molecule of

glucose?4. Where is most of the energy in pyruvic acid

transferred to in this cycle?5. What is FAD? What is its role in the cycle?

The Krebs Cycle

90% of energy in pyruvic acid still unused

Locked in the HE electrons

Discovered by Hans Krebs◦British Biochemist in 1937

Pyruvic acid from glycolysis travels into the mitochondrion

KREBS CYCLE occurs here

The Krebs Cycle

Respiration is a synonym for breathing.

Oxygen is the final electron acceptor.

This is why organisms need to breathe in oxygen.

The Krebs Cycle

Pyruvic Acid is broken down into carbon dioxide in a series of energy-extracting reactions.

Second stage of cellular respiration.

Also called the Citric Acid Cycle.

Citric Acid is the first compound fromed in this process.

The Krebs Cycle: STEP A

1. PA from Glycolysis enters mitochondria

2. One C from PA becomes part of CO2◦Released into air

3. Remaining 2 C joined with Coenzyme A

4. Forms Acetyl Coenzyme A (CoA)

5. Acetyl CoA joins with 4 C molecule to produce Citric Acid

The KREBS CYCLE: STEP B

1. Citric Acid (6-C) broken down to a 4-C molecule◦ 2 molecules of CO2 released

2. Electrons transferred to e- carriers.◦ Occurs 5 times throughout cycle.◦ NAD+ NADH FAD FADH2

3. ADP molecule ATP

One turn produces 4 NADH, 1 FADH2, 1 ATPOne turn = 1 Pyruvic acid

How many turns are made for 1 molecule of glucose?

PRODUCTS of KREBS CYCLEWhat are the products of the KREBS Cycle?ATP, NADH, FADH2, and Carbon Dioxide

How are these products used?ATP for Cellular ActivitiesCarbon Dioxide is exhaledNADH and FADH2 carry HEe- to ETC

◦Used to make huge amounts of ATP

HOMEWORK REVIEW

TEXTBOOK Page 237 and 238Answer questions 20-24 and 29-30

TEXTBOOK Page 239Answer questions 1-9

Question of the Day Nov 13

Which of the following are electron carriers?

A. NAD+B. FADC. NADHD. All of the above

DO NOW Nov 13

What are the products of the Krebs Cycle for 1 Molecule of glucose?

ANSWER

The KREBS Cycle produces

8 NADH, 2 FADH2, and 2 ATP

Per molecule of Glucose

These products are from 2 turns of the KREBS Cycle.

AGENDA NOV 13

BIG Question: How do organisms produce energy?

1. QotD and DO NOW2. Chapter 93. Electron Transport Chain4. STUDY GUIDES5. Tomorrow – Review6. TEST on FRIDAY – CHAPTER 9

ELECTRON TRANSPORT CHAIN

HEe- from KREBS are carried to ETC.◦Delivered by NADH and FADH2

STEP A: HEe- passed along the ETC◦Series of Carrier Proteins◦Inner membrane of Mitochondria◦Electrons lose a small amount of energy for each “jump” it they make along ETC.

Electron Transport ChainWhat happens to the electrons when

they reach the end of ETC?

Oxygen is the final electron acceptor.

Enzymes combine these LEe- with H ions and Oxygen to form water.

ETC: ENERGY MAKING STEPSSTEP B: For every 2 HEe- that pass

along ETC, their energy is used to transport H+ ions from the matrix to the inner-membrane space.

How many membranes does the mitochondria have?

Concentration gradient is formed.

ETC: ENERGY MAKING STEPS

STEP C: ATP SYNTHASE allows the movement of H+ ions back across the inner membrane.

This movement produces energy used to make ADP + P ATP

Each pair of HEe- that “jump” along ETC produce enough energy to produce 3 ATP

TOTALS

FOR 1 Molecule of GLUCOSE

GLYCOLYSIS produces2 NADH and 4 ATP (2 ATP SPENT)

KREBS CYCLE produces (2 Turns)8 NADH, 2 FADH2, and 2 ATP

ETC produces32 ATP

TOTALS

The overall process of Cellular Respiration produces available to the cell.

38 ATP – 2 ATP SPENT = 36 ATP

This is 38% of the energy available in Glucose.

Where does the rest of the energy go?It is lost as heat.This is why we feel hot after strenuous

activity.

ENERGY and EXERCISE

Short Term Energy◦Small amounts of ATP in muscles◦Lactic Acid Fermentation takes over◦Enough energy to last approximately 90

secondsLong Term Energy

◦Cellular respiration is needed◦Releases energy slower than fermentation◦Stored in the carbohydrate Glycogen◦15 – 20 minutes of energy (then breaks down

fats and other molecules)◦Even the most conditioned athletes must pace

themselves.