NOTES – Cell Energy Part 3 NOTES – Cell Energy Part 3 (Cellular Respiration)(Cellular Respiration)

Cell Energy ReviewCell Energy Review Cell Energy Part 1 – ATPCell Energy Part 1 – ATP

ATP is the “energy currency” of the cellATP is the “energy currency” of the cell Cells must regenerate ATP from ADP and P to Cells must regenerate ATP from ADP and P to

keep workingkeep working A constant input of energy (food) is required to A constant input of energy (food) is required to

power the ATP cyclepower the ATP cycle Cell Energy Part 2 – PhotosynthesisCell Energy Part 2 – Photosynthesis

The source of almost all food moleculesThe source of almost all food molecules Light energy is converted into chemical energy Light energy is converted into chemical energy

and stored in the bonds of high-energy and stored in the bonds of high-energy molecules molecules

These molecules are used to power the ATP These molecules are used to power the ATP cycle and are used as skeletons to build other cycle and are used as skeletons to build other molecules necessary for lifemolecules necessary for life

Metabolism – The Chemical Metabolism – The Chemical Reactions of an OrganismReactions of an Organism

MetabolismMetabolism – the set of chemical – the set of chemical reactions that happen in an organism to reactions that happen in an organism to maintain lifemaintain life Allow organisms to grow/reproduce, Allow organisms to grow/reproduce,

maintain structures, respond to maintain structures, respond to environmentenvironment

Organized into Organized into pathwayspathways, where one , where one chemical is transformed through a chemical is transformed through a series of steps into another chemicalseries of steps into another chemical

Two categories: Two categories: catabolismcatabolism and and anabolismanabolism

Metabolism – The Chemical Metabolism – The Chemical Reactions of an OrganismReactions of an Organism

CatabolismCatabolism – metabolic reactions that – metabolic reactions that release energy by breaking down complex release energy by breaking down complex molecules into simpler compoundsmolecules into simpler compounds Ex - Cells break down glucose to power Ex - Cells break down glucose to power

the ATP cycle (cell respiration)the ATP cycle (cell respiration) AnabolismAnabolism – metabolic reactions that – metabolic reactions that

store energy by building simpler store energy by building simpler compounds into more complex moleculescompounds into more complex molecules Ex - PhotosynthesisEx - Photosynthesis

Glucose-Glycogen Glucose-Glycogen MetabolismMetabolism

How do cells use food How do cells use food molecules, such as glucose, to molecules, such as glucose, to

produce ATP?produce ATP? GlycolysisGlycolysis – process where glucose is – process where glucose is

broken down into 2 pyruvic acid broken down into 2 pyruvic acid moleculesmolecules Takes place in cytoplasm of all cellsTakes place in cytoplasm of all cells Requires Requires glucoseglucose, , 2 ATP2 ATP, and , and NADNAD++ Produces Produces 2 pyruvic acid2 pyruvic acid, , 4 ATP4 ATP, and , and 2 2

NADHNADH Glucose + 2 ATP + NAD+ Glucose + 2 ATP + NAD+ 2 pyruvic acid 2 pyruvic acid

+ 4 ATP + 2 NADH+ 4 ATP + 2 NADH Net gain of 2 ATP moleculesNet gain of 2 ATP molecules

Glycolysis – What happens?Glycolysis – What happens? 4 e4 e-- are removed from are removed from

glucose and transferred glucose and transferred to to 22 NADNAD++ which which become become 2 NADH2 NADH

NADNAD++ must be present must be present to accept eto accept e-- from from glucose, otherwise glucose, otherwise glycolysis cannot take glycolysis cannot take placeplace

Small overall energy Small overall energy yield (2 ATP), but yield (2 ATP), but extremely fast processextremely fast process

After a few seconds, all After a few seconds, all of a cell’s available of a cell’s available NADNAD++ is used up is used up

What happens when there is What happens when there is no more NADno more NAD++??

Cells need a way to convert Cells need a way to convert NADHNADH back into back into NADNAD++

How they do this depends on the How they do this depends on the amount of oxygen present in the cellamount of oxygen present in the cell Insufficient oxygen = Insufficient oxygen = fermentationfermentation Plentiful oxygen = Plentiful oxygen = aerobic respirationaerobic respiration

FermentationFermentation

FermentationFermentation – process where e- – process where e- from from NADHNADH are passed back to pyruvic are passed back to pyruvic acid molecules, producing acid molecules, producing NAD+NAD+ Keeps glycolysis goingKeeps glycolysis going Anaerobic processAnaerobic process – does not require – does not require

oxygenoxygen Pyruvic acid molecules are changed into Pyruvic acid molecules are changed into

new productsnew products Most cells perform some type of Most cells perform some type of

fermentationfermentation

2 Common Types of 2 Common Types of FermentationFermentation

1.1. Alcoholic FermentationAlcoholic Fermentation – process where – process where pyruvic acidpyruvic acid accepts accepts e e-- from from NADHNADH producing ethyl alcohol, producing ethyl alcohol, COCO22, and , and NADNAD++

pyruvic acid + NADH pyruvic acid + NADH ethyl alcohol + COethyl alcohol + CO22 + + NADNAD++

Performed by yeast, plants, some bacteriaPerformed by yeast, plants, some bacteria Used to produce alcohol in wine, beer, etc.Used to produce alcohol in wine, beer, etc. Used to make bread riseUsed to make bread rise

The holes in the bread are made by bubbles of COThe holes in the bread are made by bubbles of CO22 in the dough in the dough The alcohol produced by the yeast boils away in the ovenThe alcohol produced by the yeast boils away in the oven

Honey Wheat Sandwich Honey Wheat Sandwich BreadBread

Rustic BreadRustic Bread

Italian BreadItalian Bread

French BreadFrench Bread

Ciabatta BreadCiabatta Bread

Plain and Sesame BagelsPlain and Sesame Bagels

Cinnamon Raisin BagelsCinnamon Raisin Bagels

Marble Rye BreadMarble Rye Bread

Casatiello BreadCasatiello Bread

Sourdough BreadSourdough Bread

Pane Siciliano (Sicilian Pane Siciliano (Sicilian Bread)Bread)

Oatmeal BreadOatmeal Bread

PizzaPizza

Pita BreadPita Bread

Soft PretzelsSoft Pretzels

Bretzel (Bavarian Pretzel) Bretzel (Bavarian Pretzel) RollsRolls

Hard Rolls (Kaiser Rolls)Hard Rolls (Kaiser Rolls)

2 Common Types of 2 Common Types of FermentationFermentation

2.2. Lactic Acid FermentationLactic Acid Fermentation – process – process where where pyruvic acidpyruvic acid accepts accepts ee-- from from NADHNADH producing lactic acid and producing lactic acid and NADNAD++

pyruvic acid + NADH pyruvic acid + NADH lactic acid + lactic acid + NADNAD++

Performed by animals, some bacteriaPerformed by animals, some bacteria Used to produce cheese, sour cream, Used to produce cheese, sour cream,

yogurtyogurt Responsible for quick bursts of energy in Responsible for quick bursts of energy in

animals (Ex. Sprinting)animals (Ex. Sprinting)

Different Types of Different Types of FermentationFermentation

Lactic Acid Fermentation and Lactic Acid Fermentation and ExerciseExercise

Low oxygen = body converts pyruvic Low oxygen = body converts pyruvic acid into lactic acid = continued acid into lactic acid = continued glycolysisglycolysis

After 1 to 3 minutes, lactic acid After 1 to 3 minutes, lactic acid concentration in muscles is highconcentration in muscles is high

High lactic acid = burning sensation in High lactic acid = burning sensation in muscles & less glucose breakdownmuscles & less glucose breakdown

You stop = muscle damage is preventedYou stop = muscle damage is prevented Rest + oxygen = lactic acid Rest + oxygen = lactic acid pyruvic pyruvic

acidacid

Remember…Remember… The goal of fermentation is to The goal of fermentation is to

generate generate NADNAD++ to keep glycolysis to keep glycolysis going in low oxygen conditionsgoing in low oxygen conditions

The The ee-- from from NADHNADH are passed back to are passed back to pyruvic acidpyruvic acid molecules, generating molecules, generating different products and different products and NADNAD++

If there is plenty of oxygen available, If there is plenty of oxygen available, in most cells a different process occursin most cells a different process occurs

Cellular Respiration – Cellular Respiration – OverviewOverview

After glycolysis about 90% of the After glycolysis about 90% of the chemical energy available in glucose chemical energy available in glucose is still unusedis still unused

The energy is locked up in the The energy is locked up in the pyruvic acid moleculespyruvic acid molecules

In the presence of plentiful oxygen, In the presence of plentiful oxygen, most cells can break down pyruvic most cells can break down pyruvic acid molecules further, generating acid molecules further, generating much more ATPmuch more ATP

Cellular RespirationCellular Respiration Cellular RespirationCellular Respiration – process that – process that

releases energy by breaking down releases energy by breaking down food molecules (glucose) in the food molecules (glucose) in the presence of oxygenpresence of oxygen 6 O6 O22 + C + C66HH1212OO66 6 CO 6 CO22 + 6 H + 6 H22O + 36 ATPO + 36 ATP Aerobic processAerobic process – requires oxygen – requires oxygen In eukaryotic cells, respiration takes place In eukaryotic cells, respiration takes place

in mitochondriain mitochondria In some prokaryotic cells, the entire cell In some prokaryotic cells, the entire cell

functions like a single mitochondrion, functions like a single mitochondrion, allowing respiration to be carried outallowing respiration to be carried out

Cell Respiration – What Cell Respiration – What happens?happens?

Cell Respiration is a 3-Step process:Cell Respiration is a 3-Step process:

1.1. GlycolysisGlycolysis – begins break down of – begins break down of glucoseglucose in in cytoplasm into cytoplasm into pyruvic acidpyruvic acid

2.2. Krebs CycleKrebs Cycle – breaks down – breaks down pyruvic acidpyruvic acid into into COCO22, releasing energy (in mitochondria), releasing energy (in mitochondria)

3.3. Electron Transport ChainElectron Transport Chain – generates – generates ATPATP in in mitochondria using products from the Krebs mitochondria using products from the Krebs CycleCycle

Step 1 - GlycolysisStep 1 - Glycolysis

Structure of MitochondrionStructure of Mitochondrion Outer membraneOuter membrane

– simple – simple phospholipid bilayerphospholipid bilayer

Inner membraneInner membrane – highly folded – highly folded phospholipid phospholipid bilayer, site of bilayer, site of electron transport electron transport chainchain

MatrixMatrix – inner – inner portion of portion of mitochondrion, site mitochondrion, site of Krebs Cycleof Krebs Cycle

The Krebs Cycle (Citric Acid The Krebs Cycle (Citric Acid Cycle)Cycle)

22ndnd stage of cell respiration where stage of cell respiration where pyruvic acidpyruvic acid molecules are broken down molecules are broken down producing producing COCO22, , NADHNADH, , FADHFADH22, and , and ATPATP

2 pyruvic acid 2 pyruvic acid 6 CO 6 CO22 + 8 NADH + 2 + 8 NADH + 2 FADHFADH22 + 2 ATP + 2 ATP

NADHNADH & & FADHFADH22 carry carry ee-- to the final stage to the final stage of cell respirationof cell respiration

COCO22 is a waste product is a waste product

Step 2 – Krebs CycleStep 2 – Krebs Cycle

The Electron Transport Chain The Electron Transport Chain (ETC)(ETC)

33rdrd stage of cell respiration where stage of cell respiration where ee-- from from the Krebs Cycle are used to convert the Krebs Cycle are used to convert ADPADP into into ATPATP

e-e- are passed from are passed from NADHNADH and and FADHFADH22 to a to a series of carrier proteins that are embedded series of carrier proteins that are embedded in the inner membrane of a mitochondrionin the inner membrane of a mitochondrion

As the As the ee-- pass from one protein to the next, pass from one protein to the next, HH++ ions are pulled from the matrix into the ions are pulled from the matrix into the intermembrane space of the mitochondrion intermembrane space of the mitochondrion

ee-- flow back into the matrix through flow back into the matrix through ATP ATP sythasesythase proteins, which use the energy to proteins, which use the energy to convert convert ADP ADP into into ATPATP

Using eUsing e-- to make ATP to make ATP

What happens to the What happens to the electrons?electrons?

As As ee-- reach the end of the chain, they reach the end of the chain, they must go somewhere, or else the chain must go somewhere, or else the chain cannot accept new cannot accept new ee-- from the Krebs Cyclefrom the Krebs Cycle

Oxygen molecules accept the Oxygen molecules accept the ee--, and , and immediately bond immediately bond HH++ ions, forming ions, forming HH22OO moleculesmolecules

As long as there is plentiful oxygen, As long as there is plentiful oxygen, NADHNADH is continually converted to is continually converted to NADNAD++ by the by the ETC, allowing glycolysis to continueETC, allowing glycolysis to continue

If oxygen is not brought in quickly enough, If oxygen is not brought in quickly enough, the chain slows down, the chain slows down, NADNAD++ is quickly is quickly used up, and fermentation beginsused up, and fermentation begins

Step 3 – Electron Transport Step 3 – Electron Transport ChainChain

How much energy does cellular How much energy does cellular respiration provide?respiration provide?

Overall ~ 36 ATPOverall ~ 36 ATP Glycolysis Glycolysis = = 2 ATP 2 ATP Krebs Cycle Krebs Cycle = = 2 ATP 2 ATP ETC ETC = = 34 ATP34 ATP

2 ATP are used up transporting 2 ATP are used up transporting pyruvic acid into mitochondriapyruvic acid into mitochondria

36 ATP represents about 40% of the 36 ATP represents about 40% of the energy released from glucose, the energy released from glucose, the other 60% is converted to heat energyother 60% is converted to heat energy

A variety of A variety of molecules molecules

can be used can be used by cells for by cells for

cell cell respirationrespiration

What is the relationship between What is the relationship between photosynthesis and cellular photosynthesis and cellular

respiration?respiration? They are opposite processesThey are opposite processes

Photosynthesis stores energy in glucose Photosynthesis stores energy in glucose (it is an (it is an endergonic anabolicendergonic anabolic reaction) reaction)

Respiration releases energy by breaking Respiration releases energy by breaking down glucose (it is an down glucose (it is an exergonic catabolicexergonic catabolic reaction)reaction)

The products of photosynthesis are the The products of photosynthesis are the reactants of cell respirationreactants of cell respiration

The products of cell respiration (excluding The products of cell respiration (excluding the ATP) can be recycled by the ATP) can be recycled by photosynthesisphotosynthesis

Energy enters Energy enters an ecosystem an ecosystem as lightas light

It is converted It is converted to chemical to chemical energy (glucose, energy (glucose, then ATP)then ATP)

Energy leaves Energy leaves the ecosystem the ecosystem as heat, and as heat, and must must continuously be continuously be replacedreplaced

Cell Energy ReviewCell Energy Review

Cells use ATP for energy (Cells use ATP for energy (ATP CycleATP Cycle)) Cells generate ATP by releasing Cells generate ATP by releasing

energy from food molecules energy from food molecules (glucose) during the processes of (glucose) during the processes of cell respirationcell respiration and and fermentationfermentation

Food molecules (glucose) are Food molecules (glucose) are generated during the process of generated during the process of photosynthesisphotosynthesis