CHAPTER 9CHAPTER 9

ENERGY IN A CELLENERGY IN A CELL

ENERGYENERGY

All living organisms must be able to All living organisms must be able to obtain energy from their obtain energy from their environmentenvironment

All energy comes from All energy comes from sunlightsunlight and and organisms either obtain it directly or organisms either obtain it directly or indirectlyindirectly

ADENOSINE ADENOSINE TRIPHOSPHATETRIPHOSPHATE

((ATP)ATP)

Energy storing molecule.Energy storing molecule.

Releases energy quickly whenever a Releases energy quickly whenever a cell needs it.cell needs it.

ATP StructureATP Structure

Composed of an adenosine molecule with Composed of an adenosine molecule with three phosphate molecules attached.three phosphate molecules attached.

The energy of ATP becomes available The energy of ATP becomes available when the bond is broken between the when the bond is broken between the 22ndnd and 3and 3rdrd phosphate groups. phosphate groups.

adenosineadenosineTRITRIphosphate to adenosinephosphate to adenosineDIDIphosphatephosphate

ATPATP

PhotosynthesisPhotosynthesis

The process that The process that uses sunlight to uses sunlight to make simple make simple sugars.sugars.

Contains 2 Contains 2 reactions.reactions.

Light - dependent Light - dependent reactionreaction

Requires lightRequires light in order to occur. in order to occur.

Reactants:Reactants: Sunlight and water. Sunlight and water.

Products:Products: ATP and NADPH and ATP and NADPH and releases oxygen.releases oxygen.

Light - Independent Light - Independent ReactionReaction

Also known as the Also known as the dark cycledark cycle oror calvin calvin cycle.cycle.

Does not need sunlightDoes not need sunlight in order to occur. in order to occur.

Reactants:Reactants: ATP, NADPH, and Carbon ATP, NADPH, and Carbon dioxide.dioxide.

Products:Products: Glucose and Pgal. Glucose and Pgal.

Calvin Cycle

OR

Dark Cycle

Formula for Formula for photosynthesisphotosynthesis

6CO6CO22 + 6H + 6H22O + sunlight O + sunlight → C→ C66HH1212OO66 + 6O + 6O22

ChloroplastChloroplast

The plant organelle in which The plant organelle in which photosynthesis occurs.photosynthesis occurs.

Contains pigments called Contains pigments called chlorophyllchlorophyll that absorbs most that absorbs most wavelengths of light except green.wavelengths of light except green.

ChloroplastChloroplast

Aerobic Cellular Aerobic Cellular RespirationRespiration

(with Oxygen)(with Oxygen) Breakdown of sugar (food) into ATP Breakdown of sugar (food) into ATP

(usable energy).(usable energy). Occurs in the Occurs in the mitochondria.mitochondria.

3 phases:3 phases:1. 1. glycolysis:glycolysis: Anaerobic (no oxygen) Anaerobic (no oxygen)

*Steps 2&3 with oxygen*Steps 2&3 with oxygen2. 2. citric acid cyclecitric acid cycle (kreb cycle) (kreb cycle)3. 3. electron transport chainelectron transport chain

MitochondriaMitochondria

Formula for aerobic Formula for aerobic respirationrespiration

Opposite of photosynthesis.Opposite of photosynthesis.

CC66HH1212OO66 + O + O22 → 6CO→ 6CO22 + 6H + 6H22O + O + energyenergy

GLYCOLYSISGLYCOLYSIS(sugar splitting)(sugar splitting)

AnaerobicAnaerobic: : no oxygenno oxygen is used. is used. Takes the Takes the 6-Carbon glucose6-Carbon glucose and breaks it and breaks it

into into 2, 3-Carbon pyruvic acid2, 3-Carbon pyruvic acid molecules. molecules.

Glycolysis Cont…Only produces Only produces 2 ATP2 ATP molecules molecules

Glycolysis Cont…Glycolysis Cont…

Pyruvic acid is then converted into Pyruvic acid is then converted into Acetyl Co-enzyme AAcetyl Co-enzyme A before it enters before it enters the citric acid cycle.the citric acid cycle.

Reactants:Reactants: Glucose Glucose

Products:Products: Pyruvic Acid Pyruvic Acid

CITRIC ACID CYCLECITRIC ACID CYCLE(Also called the Kreb Cycle)(Also called the Kreb Cycle)

During this process high energy electrons are During this process high energy electrons are captured by captured by NADHNADH and and FADHFADH22. (electron . (electron carriers)carriers)

Pulls carbons off the sugar molecules, Pulls carbons off the sugar molecules, releasing carbon dioxide and generating releasing carbon dioxide and generating 2 2 ATP ATP (varies)(varies)..

Reactants:Reactants: Acetyl Co-enzyme A Acetyl Co-enzyme A Products:Products: NADH and FADH NADH and FADH22

Kreb CycleKreb Cycle((Citric Acid Cycle)Citric Acid Cycle)

ELECTRON TRANSPORT ELECTRON TRANSPORT CHAINCHAIN

The electron carriers The electron carriers NADHNADH and and FADHFADH22 transfer their electrons to the transfer their electrons to the electron transport chain.electron transport chain.

The electrons are passed through a The electrons are passed through a series of proteins, gradually releasing series of proteins, gradually releasing the energy they contain, to form the energy they contain, to form 32 32 ATPATP molecules. molecules.

The final electron acceptor is The final electron acceptor is oxygenoxygen..

Electron Transport Chain

Aerobic RespirationAerobic Respiration

Anaerobic RespirationAnaerobic Respiration(No oxygen)(No oxygen)

Lactic acid Lactic acid fermentation:fermentation: Occurs during Occurs during strenuous exercisestrenuous exercise when the body is not when the body is not able to supply needed able to supply needed oxygen to the muscles. oxygen to the muscles.

Allows the continued Allows the continued production of ATP until production of ATP until oxygen levels are oxygen levels are restoredrestored..

Anaerobic Respiration Anaerobic Respiration Cont...Cont...

No Oxygen!!!No Oxygen!!! Occurs in the Occurs in the cytoplasmcytoplasm of the of the

cell.cell. Produces lactic acid.Produces lactic acid.

Not very efficient – Only Not very efficient – Only 2 ATP2 ATP produced.produced.

Anaerobic Respiration Anaerobic Respiration Cont..Cont..

Alcoholic FermentationAlcoholic Fermentation

Used by yeast and some Used by yeast and some bacteria.bacteria.

Produces carbon dioxide and Produces carbon dioxide and alcohol.alcohol.