AP Bio Ch 9, part 1

An Overview of Cellular

Respiration

An Overview of Cellular

RespirationChapter 9Chapter 9

He’s getting

chemical

energy from

his food!

DO NOW

• Take out a piece of binder paper & fold it into thirds

1.1. Top third – furthest place Top third – furthest place you’ve ever traveledyou’ve ever traveled

2.2. Middle third – name of your Middle third – name of your first pet first pet

3.3. Bottom third – last person Bottom third – last person you huggedyou hugged

Ankara, Turkey

Tiger Tiger

MitchMitch

The Big PictureThe Big Picture• All cells require energy to do their work

• Cellular respiration produces this energy

• All cells require energy to do their work

• Cellular respiration produces this energy

What is cellular respiration?

What is cellular respiration?

• It is the main way that chemical energy is harvested from food

• Food molecules have LOTS of energy – but that energy can’t be used all at once

• Food energy is stored as ATP energy

• It is the main way that chemical energy is harvested from food

• Food molecules have LOTS of energy – but that energy can’t be used all at once

• Food energy is stored as ATP energy

Breathing

Cellularrespiration

Musclecells

Cellular respiration releases energy

Cellular respiration releases energy

• Cellular respiration is catabolic and exergonic

C6H12O6 + 6O2 --> 6CO2 + 6H2O + Energy (ATP and heat)

∆G = -686 kcal/mol of glucose broken down

• Cellular respiration is catabolic and exergonic

C6H12O6 + 6O2 --> 6CO2 + 6H2O + Energy (ATP and heat)

∆G = -686 kcal/mol of glucose broken down

• The energy released is stored in molecules of ATP

• ATP is then used to power the cell

• The energy released is stored in molecules of ATP

• ATP is then used to power the cell

• Catabolic reactions are not directly used to power the cell

• Catabolic reactions are not directly used to power the cell

Quick Think 1 – hug buddies

Quick Think 1 – hug buddies

• Why don’t organisms use the metabolic breakdown of food directly to power the cell?

• In other words, why bother making ATP?

• Why don’t organisms use the metabolic breakdown of food directly to power the cell?

• In other words, why bother making ATP?

General Information about redox reactions

General Information about redox reactions

• Redox = oxidation-reduction reactions

• Cellular respiration is a series of redox reactions

• Redox = oxidation-reduction reactions

• Cellular respiration is a series of redox reactions

Many chemical reactions involve the transfer of electrons from

one molecule to another

Many chemical reactions involve the transfer of electrons from

one molecule to another

• These kinds of reactions are called redox reactions

• These kinds of reactions are called redox reactions

• The loss of electrons from a substance = oxidation

• The addition of electrons to a substance = reduction

• The loss of electrons from a substance = oxidation

• The addition of electrons to a substance = reduction

• The electron donor = reducing agent (it reduced the other substance)

• The electron acceptor = oxidizing agent

• The electron donor = reducing agent (it reduced the other substance)

• The electron acceptor = oxidizing agent

Quick Think 2 – travel buddy

Quick Think 2 – travel buddy

• In the following redox reaction, which compound is oxidized and which is reduced?

C4H6O5 + NAD+ C4H4O5 + NADH + H+

• In the following redox reaction, which compound is oxidized and which is reduced?

C4H6O5 + NAD+ C4H4O5 + NADH + H+

Oxygen is a powerful oxidizing agent

Oxygen is a powerful oxidizing agent

• Oxygen is very electronegative

• The more electronegative an atom is, the more energy it takes to pull away its electrons

• Oxygen is very electronegative

• The more electronegative an atom is, the more energy it takes to pull away its electrons

When electrons move from a less electronegative atom to a more electronegative atom, it releases

energy

When electrons move from a less electronegative atom to a more electronegative atom, it releases

energy

• A reaction that puts electrons closer to oxygen releases energy

• A reaction that puts electrons closer to oxygen releases energy

Respiration - the oxidation of glucose by oxygen

Respiration - the oxidation of glucose by oxygen

• During cellular respiration, hydrogen and its bonding electrons change partners

• Hydrogen and its electrons go from sugar to oxygen, forming water

• During cellular respiration, hydrogen and its bonding electrons change partners

• Hydrogen and its electrons go from sugar to oxygen, forming water

Oxidation[Glucose loses electrons (and hydrogens)]

Reduction[Oxygen gains electrons (and hydrogens)]

The Overall Equation for Cellular Respiration

Oxidation:Glucose loses electrons(and hydrogens)

Glucose Carbon dioxide

Electrons(and hydrogens) Energy

Oxygen

Reduction:

Oxygen gainselectrons (andhydrogens)

• Why does transferring electrons to oxygen release energy?

• Why does transferring electrons to oxygen release energy?When electrons move from glucose to oxygen, it is as though they were fallingThis “fall” of electrons releases energy during cellular respiration

Releaseof heatenergy

Glucose is a good fuelGlucose is a good fuel

• It has a lot of hydrogens• Makes it a reservoir of

electrons• Those electrons want to go

to a lower energy state by moving toward the more electronegative oxygen

• It has a lot of hydrogens• Makes it a reservoir of

electrons• Those electrons want to go

to a lower energy state by moving toward the more electronegative oxygen

Quick Think 3 – pet buddyQuick Think 3 – pet buddy• Redox reactions involve ___________.

• Oxygen is very __________ so it is a good _________.

• In cellular respiration, oxygen is used to _________ glucose, thereby releasing __________ due to the fall of ___________ from glucose to ____.

• Redox reactions involve ___________.

• Oxygen is very __________ so it is a good _________.

• In cellular respiration, oxygen is used to _________ glucose, thereby releasing __________ due to the fall of ___________ from glucose to ____.

• Enzymes help glucose get oxidized in a series of controlled steps

• So that the energy being released is released in a controlled, useful way

• Enzymes help glucose get oxidized in a series of controlled steps

• So that the energy being released is released in a controlled, useful way

Overall redox summary of

cellular respiration

Overall redox summary of

cellular respiration• Cellular respiration = electrons in

glucose --> NADH --> electron transport chain --> oxygen

• Cellular respiration = electrons in glucose --> NADH --> electron transport chain --> oxygen