Cellular Respiration

Cellular Respiration

• Process that makes energy for all life on earth• It is the transfer of chemical bond energy of

organic molecules to the chemical bond energy of ATP

• Remember:– Making chemical bonds stores energy– Breaking chemical bonds releases energy

• Respiration breaks the bonds of glucose, so it releases energy

Harvesting energy stored in food• Cellular respiration– breaking down food to produce ATP• in mitochondria• using oxygen

– “aerobic” respiration

– usually digesting glucose• but could be other sugars,

fats, or proteins

C6H12O6 6O2 ATP 6CO2 6H2O+ + +

glucose + oxygen energy + carbon + water dioxide

O2

food ATP

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

Plantl Cells

Animal Cells

MitochondrionOuter membrane Intermembrane

space

Inner membrane

Matrix

Can’t store ATP too unstableonly used in cell

that produces itonly short term

energy storagecarbohydrates & fats

are long term energy storage

Using ATP to do work?

A working muscle recycles over 10 million ATPs per second

ATP

ADP

work

Adenosine DiPhosphate

Adenosine TriPhosphate

make energy

A Body’s Energy Budget

eatfood

synthesis(building)

• energy needed even at rest

• activity• temperature

control{• growth• reproduction• repair{

storage• glycogen

(animal starch)• fat{

ATP

1

2

3

ADP vs. ATP

ATP Factoid

• On average, the human body contains 250 grams of ATP

• The amount of ATP used by the human body in a day equals the body weight of the individual.

Cellular Respiration

• Occurs in 3 Distinct Phases– The first stage, glycolysis, is anaerobic—no oxygen is

required.– The last two stages are aerobic and require oxygen to be

completed.

SUMMARY EQUATION:

STAGES OF CELLULAR RESPIRATION

• Respiration occurs in three main stages

GLYCOLYSIS KREBSCYCLE

ELECTRONTRANSPORT CHAIN

High-energy electrons carried by NADH

MitochondrionCytoplasmicfluid

Glycolysis Glyco=sweet, sugar lysis = to splitGlycolysis: a series of chemical reactions in the cytoplasm of a cell that break down glucose, a six-carbon compound, into two molecules of pyruvic acid, a three-carbon compound• produces two ATP molecules for each glucose molecule

broken down.

• 2 molecules of NADH are formed

The Transition Phase *(we’ll include this as part of Kreb’s)

• Before Krebs Cycle and electron transport chain can begin, pyruvic acid undergoes a series of reactions in which it gives off a molecule of CO2 and combines with a molecule called coenzyme A to form acetyl-CoA.

Pyruvicacid

Acetyl CoA(acetyl coenzyme A)

CO2

Glycolysis Summary

• Produces 2 ATP– 2 ATP were needed for the reaction– 4 ATP were made in the reaction

• Creates 2 NADH molecules– Passed to Electron Transport Chain

• Glucose (6 C’s) has been broken down to form 2 molecules of pyruvic acid (3 C’s)– Converted into Acetyl CoA

The Krebs Cycle• Series of reactions that

occurs in mitochondrial matrix– Breaks pyruvic acid down into

CO2, releasing energy

• For every one turn of the cycle, one molecule of ATP, two molecules of carbon dioxide, 3 NADH, 1 FADH2 are produced.

• Per molecule of glucose, Kreb’s creates:• 2 ATP• 6 NADH• 2 FADH2

• 4 CO2

CO2

Other Energy Molecules…

• NAD and FAD– Hydrogen and electron carriers– Bring hydrogen/electrons to the electron transport

chain where they are used to make more ATP• Hydrogen and Electrons are sources of potential energy• Energy can be released to make ATP

The electron transport chain• In the electron transport chain, the carrier

molecules NADH and FADH2 give up electrons that pass through a series of reactions. Oxygen is the final electron acceptor forming water.

• This sets up a H+ (proton) gradient• Allow the protons to flow through ATP

synthase which synthesizes ATP (ADP + Pi = ATP)

ETC continued…

• The electron transport chain adds 32 ATP molecules to the four already produced during glycolysis & Krebs cycle

• Occurs in the inner mitochondrial membrane

ETC

• Located in the Mitochondria• Produces 32 ATP• For each pair of Hydrogen atoms brought in

by:– NAD: 3 ATP molecules are made– FAD” 2 ATP molecules are made

In summary, what do we need to make energy?

• The “Furnace” for making energy– mitochondria

• Fuel– food: carbohydrates, fats, proteins

• Helpers– oxygen– enzymes

• Product– ATP

• Waste products– carbon dioxide

• then used by plants– water

O2

food

ATP

enzymes

CO2 H2O

Summary Facts : Cellular Respiration  

• Reactants/Raw materials :  oxygen + sugar (glucose, starch, food, fats)  

• Energy Source: chemical bond energy of organic comp’ds  

• Products Made : carbon dioxide, water, ATP (energy)  

• When does it occur?: all the time, constantly, 24/7  

• Location in the Cell: mitochondria   • Organisms that use it: all living things