AP Biology Introduction to Cellular Respiration Ch. 7

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 – middle nameMiddle third – middle name3.3. Bottom third – last person Bottom third – last person

you huggedyou hugged

Ankara, Turkey

Ruth Ruth

My momMy mom

An Overview of Cellular

RespirationChapter 7

He’s getting

chemical

energy from

his food!

Big DiagramDiagrams – 1 per team• Phase 1: Glycolysis – glucose

enters cell and is broken in half to make pyruvate

• Phase 2: Formation of Acetyl-CoA – pyruvate enters mitochondria and acetyl-CoA is formed

• Phase 3: Kreb’s Cycle (aka citric acid cycle) – complete breakdown of acetyl-CoA

• Phase 4: Electron Transport Chain – the formation of a hydrogen ion gradient

• Phase 5: Chemiosmosis – formation of ATP

Include• Everything!• Be consistent with colors

with other teams• Be consistent with size with

other teams

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

• Cellular respiration produces this energy

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

Breathing

Cellularrespiration

Musclecells

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

• 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

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?

General Information about 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• 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 electron donor = reducing agent (it reduced the other substance)

• The electron acceptor = oxidizing agent

Quick Think 2 – travel buddy

• 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 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

• A reaction that puts electrons closer to oxygen releases energy

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

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?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 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

Quick Think 3 – middle 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 ____.

• 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• Cellular respiration = electrons in

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

Big DiagramDiagrams – 1 per team• Phase 1: Glycolysis – glucose

enters cell and is broken in half to make pyruvate

• Phase 2: Formation of Acetyl-CoA – pyruvate enters mitochondria and acetyl-CoA is formed

• Phase 3: Kreb’s Cycle (aka citric acid cycle) – complete breakdown of acetyl-CoA

• Phase 4: Electron Transport Chain – the formation of a hydrogen ion gradient

• Phase 5: Chemiosmosis – formation of ATP

Include• Everything!• Be consistent with colors

with other teams• Be consistent with size with

other teams