Introduction to Cell Respiration

Energy and redox reactions

The Pathway of energy in living organisms

Light energy from the sun

Chemical energy stored in glucose, fats, or carbohydrates

Chemical energy for use in the form of ATP

photosynthesis cellular respiration

All living organisms must perform cellular respiration (plants and animals) to get ATP.

Only photosynthetic organisms like plants or blue-green alga can transform light energy into chemical energy

MMMMM…..

Non-photosynthetic organisms (like humans) must consume glucose, fats, and carbohydrates to obtain the energy to produce ATP

Autotrophs = Organisms that make their own food (usually from photosynthesis).

Heterotrophs = Organisms that can't make their own food so they take in food produced by autotrophs (by eating autotrophs or organisms that eat autotrophs)

Energy flow and chemical recycling in ecosystems

Catabolism

Anabolism

Overview of Cellular Respiration

The energy released from the catabolism of glucose is used to make ATP from ADP

ADP + P + energy

ATP

• A series of reduction-oxidation reactions allow for the slow release of energy in glucose so that it can be harnessed to fuel the production of ATP.

energy

energy energy

Vs.

One large reaction Several smaller reactions

Redox Reactions: LEO the lion goes GER

• Loss of Electrons = Oxidation

• Gain of Electrons = Reduction

• Reduced compounds have higher energy because they gain the energy associated with the electrons they gain

Burning methane: an exergonic reaction

Your turn: Which molecule is reduced and which is oxidized?

CO O H HEnergy

Carbon dioxide Water

2 Hydrogen Formaldehyde

O H HOC

H

H

Reduction(takes energy)

Oxidation(releasesEnergy)

NADH(electron carrier)

Redox reactions transfer electrons and energy from carrier molecules during cellular respiration

NAD+ (oxidized, lower energy)

NADH(reduced, higher energy)

NAD+

GLYCOLYSIS KREBS CYCLEELECTRON TRANSPORT AND OXIDATIVE PHOSPHORYLATION

ATP ATP ATP

KrebsCycle

Glucose

NADH

NADH

NADH FADH2

CO2

CO2

H2O

Electron transport chain...

Py

ruva

te

Cell Respiration is separated into 3 stages

Energy/electrons are transferred from glucose to convert NAD+ to NADH, which is used in the ETC to make ATP

Figure 9.6 An overview of cellular respiration (Layer 1)

Figure 9.6 An overview of cellular respiration (Layer 2)

Figure 9.6 An overview of cellular respiration (Layer 3)

Cellular respiration is carefully regulated:

when ATP is abundant, respiration slows down

when ATP is needed, respiration speeds up