Chapter 9 Cellular Respiration

Chapter 9 Cellular

Respiration

Ms. Martinez

Glucose

Glycolysis

Cytoplasm

Pyruvic acid

Electrons carried in NADH

Krebs Cycle

Electrons carried in NADH and

FADH_{2 Electron}

Transport Chain

Mitochondrion

Mitochondrion

Athletes get the energy they need

from the breakdown of glucose during

cellular respiration.

Respiration Overview

Living things get most of the

energy they need from glucose.

 Autrotrophs make glucose using photosynthesis

 Heterotrophs get glucose from food they eat

How? 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:

6O

+ C

H

O

→ 6CO

+ 6H

O + Energy

→

There are three stages of cellular

respiration:

 Glycolysis

 Krebs Cycle

 Electron Transport

Each of the three stages captures some of the chemical energy available in food molecules and uses it to produce ATP.

Glycolysis—Stage #1

The process begins with a pathway

called glycolysis.

Glycolysis is the process in which a

glucose molecule is split in half.

Glycolysis takes place in the

cytoplasm of a cell.

This forms

two molecules of

pyruvic acid,

a 3-carbon

compound.

Through

glycolysis,

the cell gains

4 ATP

molecules or

2”net”

molecules.

How? 4ATP –

2ATP= 2

“net” ATP

produced

In addition, the electron carrier NAD+ accepts a

pair of high-energy electrons,

producing NADH.

By doing this,

NAD+ helps pass energy from

glucose to other pathways in the cell.

Glycolysis Summary

Occurs in the cytoplasm

2 “net” ATP molecules

are produced

2 pyruvic acid, 3-

carbon, molecules are

produced

Does not require

oxygen to occur

Mitochondria

The mitochondrion

(singular) is the organelle of Cellular Respiration.

Mitochondria combine oxygen with food

molecules to obtain

energy, ATP molecule, for the cell.

In plant and animal cells, the second and third

stages of cellular

respiration take place in mitochondria.

Mitochondria contain

some DNA, the molecule that carries genetic

information.

A mitochondrion has two membranes.

The second stage of cellular respiration, the Krebs Cycle,

take place in the matrix.

The matrix is the inner compartment of the mitochondrion filled with about half water and half

protein.

The third stage of

cellular respiration,

Electron Transport,

takes place in the

cristae.

The cristae is the

folded up inner

membrane.

Mitochondrion Summary

The mitochondrion is the only place in the cell where oxygen can be combined with food molecules to release the energy in them for use by the cell.

Mitochondria contain some DNA.

The second stage of cellular respiration, the Krebs Cycle, take place in the matrix.

The third stage of cellular respiration, Electron Transport, takes place in the cristae.

Krebs Cycle—Stage #2

Because the pathways of cellular

respiration require oxygen, they are

said to be aerobic.

The term cellular respiration to refer

to energy-releasing pathways within

the cell that require oxygen.

During the Krebs cycle, pyruvic acid, 3 carbon molecule, is broken down into carbon dioxide in a series of energy- extracting reactions.

The Krebs cycle is also known as the citric acid cycle, because citric acid is one of its first products.

The Krebs cycle occurs in the matrix.

The matrix is the inner compartment of the mitochondrion filled with about half water and half protein.

Here are the stages of the Krebs cycle.

• The Krebs cycle starts when pyruvic acid formed by glycolysis enters the mitochondrion.

• This step requires

oxygen. ^CO2

• The pyruvic acid is

broken down into

carbon dioxide.

• The carbon dioxide is

released as a waste

product.

• The Krebs cycle

continues in a series

of reactions.

CO²

•In these reactions, two energy carriers, NAD+

and FAD+, accept high- energy electrons.

•NAD+ is changed to NADH, and FAD+ is changed to FADH².

•These molecules carry the high-energy electrons to the electron transport

chain.

Krebs Cycle Summary

Requires oxygen.

Pyruvic acid is the starting 3-carbon

molecule.

Carbon dioxide is the waste product.

Occurs in the matrix.

Produces some ATP.

Electron Transport—Stage #3

The electron transport

chain uses the high-energy electrons, NADH and

FADH², to change ADP into ATP.

Electron Transport is known as the Energy Extraction phase since many ATP molecules are produced.

It occurs in the cristae.

In the

electron

transport

chain, high

energy

electrons

move from

one carrier

protein to

the next.

At the end of the chain, oxygen pulls electrons from the electron chain.

Oxygen is the final electron acceptor.

These electrons join with hydrogen ions, H+, forming water.

Each transfer

along the chain

releases a

small amount

of energy.

ATP synthase

uses the

energy to

produce ATP.

Electron Transport Summary

Requires Oxygen.

Uses the high-energy electrons,

NADH and FADH

, to change ADP into

ATP.

Water is produced.

Occurs in the cristae.

Produces many ATP molecules.

Cellular Respiration Flowchart

*From 1 molecule of glucose, up to 36

ATP molecules are made.

1 Glucose (C₆H₁₂0₆)

+ Oxygen

(0₂)

Glycolysis

CYTOPLASM

Krebs Cycle MATRIX

Carbon Dioxide

(CO²) Released

Electron Transport

Chain CRISTAE

Water (H2O) Formed

36 ATP

produced

Glucose _Glycolysis

Cytoplasm

Pyruvic acid

Electrons carried in NADH

Krebs Cycle

Electrons carried in NADH and

FADH₂

Electron Transport

Chain

Mitochondrion

Mitochondrion

CO2

H2O

Respiration vs. Photosynthesis

The energy flows in photosynthesis and cellular respiration occur in opposite

directions.

On a global level, photosynthesis and cellular respiration are also opposites.

Photosynthesis removes carbon dioxide from the atmosphere and puts back

oxygen.

Cellular respiration removes oxygen from the atmosphere and puts back carbon

dioxide.