Chapter 9.3 Cellular Respiration Mrs. Geist Biology Swansboro High School Fall 2010-2011

Chapter 9.3 Cellular RespirationMrs. GeistBiologySwansboro High SchoolFall 2010-2011

Warm-Up 9/28/2010

Given the equation for cellular respiration, explain it using words and relate it to the equation for photosynthesis.

C6H12O6 + 6 O2 6CO2 + 6H2O

Essential Questions 9/28/2010

How do light reactions relate to the overall process of photosynthesis?

How does the Calvin cycle relate to the overall process of photosynthesis?

How does the glycolysis relate to the overall process of aerobic cellular respiration?

Photosynthesis vs. Cellular Respiration

The energy flows in photosynthesis and cellular respiration take place in opposite directions. Photosynthesis removes carbon dioxide from the atmosphere and cellular respiration puts it back. Photosynthesis releases oxygen into the atmosphere and cellular respiration uses that oxygen to release energy from food.

Photosynthesis

Cellular Respiration

9-3 Getting Energy to Make ATP Food serves as a source of raw materials for the cells

in the body and as a source of energy.

Animal

Plant

Animal Cells

Plant Cells

Mitochondrion

Chemical Energy and Food

1g of glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories of heat energy.

A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

Cells don't “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds.

This process begins with a pathway called glycolysis. Glycolysis releases a small amount of energy. Takes place in the cytoplasm.

Overview of Cellular Respiration Glycolysis does not require oxygen. If oxygen is present, glycolysis is followed by the Krebs cycle and

the electron transport chain. 3 Stages of Cellular Respiration:

Glycolysis Occurs in the cytoplasm

the Krebs cycle Occurs in the mitochondria

the electron transport chain Occurs in the mitochondria Each of the 3 stages of cellular respiration captures some of the

chemical energy available in food molecules and uses it to produce ATP.

Copyright Pearson Prentice Hall

Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria.

Animal Cells

Plant Cells

MitochondrionOuter membrane Intermembrane

space

Inner membrane

Matrix

Mitochondria

Copyright Pearson Prentice HallOverview of Cellular Respiration

Cytoplasm

Pyruvicacid

Mitochondrion

Electrons carried in NADH

Electrons carried in NADH and FADH2

Glucose Glycolysis

Cellular Respiration Cellular respiration is the process that

releases energy by breaking down glucose and other food molecules in the presence of oxygen.

The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen + glucose → carbon dioxide + water +

energy

Glycolysis Glycolysis is the process in which one molecule of glucose is broken in

half, producing 2 molecules of pyruvic acid, a 3-carbon compound.

The cell uses up 2 molecules of ATP to start the reaction but produces 4 ATP molecules 2 net ATP.

2 ADP 4 ADP 4 ATP

2 Pyruvicacid

2 ATP

Glycolysis One reaction of glycolysis removes 4 high-energy electrons, passing

them to an electron carrier called NAD+ and becomes an NADH molecule.

The NADH molecule holds the electrons until they can be transferred to other molecules in the Electron Transport Chain.

2 Pyruvicacid

4 ADP 4 ATP2 ADP2 ATP

2NAD+ 2

To the electrontransport chain

Fermentation When oxygen is not present, glycolysis is followed by a

different pathway. The combined process of this pathway and glycolysis is

called fermentation.

Fermentation releases energy from food molecules by producing ATP in the absence of oxygen. Fermentation does not require oxygen—it is an

anaerobic process.

During fermentation, cells convert NADH to NAD+ by passing high-energy electrons back to pyruvic acid. This action converts NADH back into NAD+

It allows glycolysis to continue producing a steady supply of ATP.

2 Types of Fermentation1. Lactic Acid Fermentation

In many cells, pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid. Ex: muscle cells

Build-up of pyruvic acid causes muscle soreness Pyruvic acid + NADH → lactic acid + NAD+

2. Alcoholic Fermentation Yeasts and a few other microorganisms

Ex: Bakers Yeast Alcoholic fermentation gives off CO2, which causes bread

to rise Ex: Milk is converted to yogurt by microorganisms in milk

which undergo alcoholic fermentation producing acid pyruvic acid + NADH → ethyl alcohol + CO2 + NAD+

The raw materials required for cellular respiration are carbon dioxide and oxygen. glucose and water. glucose and oxygen. carbon dioxide and water.

9-3 Question 1


Glycolysis occurs in the mitochondria. cytoplasm. nucleus. chloroplasts.

9-3 Question 2


The net gain of ATP molecules after glycolysis is 3 ATP molecules. 2 ATP molecules. 3 pyruvic acid molecules. 4 pyruvic acid molecules.

9-3 Question 3


Fermentation releases energy from food molecules in the absence of oxygen. glucose. NADH. alcohol.

9-3 Question 4


The first step in fermentation is always lactic acid production. the Krebs cycle. glycolysis. alcohol production.

9-3 Question 5

The Krebs Cycle & Electron Transport Chain

Oxygen is required for the final steps of cellular respiration. Because the pathways of cellular respiration require oxygen,

they are aerobic.

In the presence of oxygen, pyruvic acid produced in glycolysis passes to the second stage of cellular respiration, the Krebs cycle.

Occurs in the mitochondria

pyruvic acid is broken down into carbon dioxide. The energy tally from 1 molecule of pyruvic acid is

3 NADH 1 FADH2 1 ATP

Electron Transport Chain (ETC)

What does the cell do with all those high-energy electrons in carriers like NADH?

In the presence of oxygen, those high-energy electrons can be used to generate huge amounts of ATP.

The ETC uses the high-energy electrons from the Krebs cycle to convert ADP into ATP.

High-energy electrons from NADH and FADH2 are passed along the electron transport chain from one carrier protein to the next.

Copyright Pearson Prentice HallElectron Transport Chain High-energy electrons from NADH and FADH2 are

passed along the electron transport chain from one carrier protein to the next.

As the final electron acceptor of the electron transport chain, oxygen gets rid of the low-energy electrons and hydrogen ions.

Net 32 ATP

Krebs Cycle & Electron Transport On average, each pair of high-energy electrons that

moves down the electron transport chain provides enough energy to produce three molecules of ATP from ADP.

Glycolysis produces just 2 ATP molecules per molecule of glucose. Fermentation yields only 2 ATP.

The complete breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP.


The Krebs cycle breaks pyruvic acid down into oxygen. NADH. carbon dioxide. alcohol.

9-2 Question 1


What role does the Krebs cycle play in the cell? It breaks down glucose and releases its stored energy.

It releases energy from molecules formed during glycolysis.

It combines carbon dioxide and water into high-energy molecules.

It breaks down ATP and NADH, releasing stored energy.

9-2 Question 2


In eukaryotes, the electron transport chain is located in the cell membrane. inner mitochondrial membrane. cytoplasm. outer mitochondrial membrane.

9-2 Question 3


To generate energy over long periods, the body must use stored ATP. lactic acid fermentation. cellular respiration. glycolysis.

9-2 Question 4


Which statement correctly describes photosynthesis and cellular respiration? Photosynthesis releases energy, while cellular

respiration stores energy. Photosynthesis and cellular respiration use the same

raw materials. Cellular respiration releases energy, while

photosynthesis stores energy. Cellular respiration and photosynthesis produce the

same products.

9-2 Question 5

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Chapter 9.3 Cellular Respiration Mrs. Geist Biology Swansboro High School Fall 2010-2011