PHOTOSYNTHESISChapter 8

ENERGY & LIFE

ENERGYThe ability to do work.

Can be stored in chemical bonds.

Cells need energy to do things like active transport, dividing, moving, and producing and storing proteins.

http://www.youtube.com/watch?v=qybUFnY7Y8w

https://www.youtube.com/watch?v=YWk9N92-wvg

ATP (ADENOSINE TRIPHOSPHATE) The main energy storage compound for living

things.

ATP is NOT good to storing lots of energy for a long time (glucose is used then).

Has three phosphate groups.

ADP (ADENOSINE DIPHOSPHATE) Same as ATP, but with only two phosphate

groups.

When a cell has extra energy, it stores it by adding a phosphate group to ADP, making ATP.

To release the energy, the bond is broken, converting ATP back to ADP.

PHOTOSYNTHESIS: ANOVERVIEW

LIGHT & PIGMENTWhite light is actually a mixture of different

wavelengths of light.

Pigments: light absorbing molecules that gather the sun’s energy. The plant’s principle pigment is chlorophyll.

Energy absorbed by chlorophyll is transferred directly to electrons in the chlorophyll molecule. These high energy electrons make photosynthesis work.

SO WHY ARE LEAVES GREEN?• Look at the wavelengths of light that chlorophyll absorbs & uses in photosynthesis• The colors that are left are reflected back and that is what you see.

Why Leaves Change Color

ENERGY CARRIERS NADP+: an “uncharged” energy carrier

• Similar to ADP

NADPH: the “charged” version Similar to ATP

PHOTOSYNTHESIS: AN OVERVIEW● THE PROCESS THAT CAPTURES LIGHT ENERGYAND USES IT TO MAKE CARBOHYDRATES (GLUCOSE).

6H2O + 6CO2 ----------> C6H12O6+ 6O2

sunlight

Carbon Dioxide: Comes in from the

air

Water: Comes in through the roots

Glucose: Stored as chemical energy

Oxygen: leaves back to the air

FACTORS AFFECTINGPHOTOSYNTHESIS Temperature

Best between 0 & 35˚C Light intensity

A higher intensity increases the rate of photosynthesis until a maximum rate is reached.

Water A shortage can stop photosynthesis.

http://www.youtube.com/watch?v=LgYPeeABoUs

THE PROCESS OFPHOTOSYNTHESIS

WHERE DOES IT TAKE PLACE? In the chloroplasts.

PHOTOSYNTHESIS 2 Parts:

Light dependent reactions Light independent reactions (AKA the Calvin Cycle)

LIGHT DEPENDENTREACTIONS1.) chlorophyll absorbs

light

2.) H2O is split; O2 is released

3.) energy is transferred to energy carriers (ATP & NADPH), which go to the Calvin cycle

LIGHT INDEPENDENTREACTIONS/ THE CALVIN CYCLE

1.) energy carriers are broken down, uncharged versions are recycled back to the light dependent reaction

2.) the energy released is used to convert CO2to C6H12O6

CELLULARRESPIRATION & FERMENTATIONChapter 9

CELLULARRESPIRATION: ANOVERVIEW

CALORIEThe amount of energy needed to

raise 1g of H2O 1○ C. When burned, 1g of glucose

releases 3811 calories of heat energy.

Food labels show Calories (= 1000calories).

TWO MORE ELECTRONCARRIERSNAD+ & FAD: “uncharged” energy

carriers • Similar to ADP

NADH & FADH2: the “charged” versions Similar to ATP

CELLULAR RESPIRATION Releases energy (ATP) by breaking down food in

the presence of oxygen.

C6H12O6 + 6O2 ----------> 6H2O + 6CO2

Glucose: Plants- have it

stored from photosynthesis; Animals- get it

from food

Water: released as waste

Oxygen: taken in from the

air

Carbon Dioxide: released into the

air

THE PROCESS OFCELLULAR RESPIRATION

CELLULAR RESPIRATIONThree parts:• Glycolysis• Kreb’s cycle• Electron Transport Chain

GLYCOLYSIS Where? The cytoplasm1.) C6H12O6 is split to form 2 pyruvic acids (2C3H6O3)2.) the energy is captured in ATP & energy carriers

KREB’S CYCLE Where? The

mitochondria1.) 2 pyruvic acids

(2C3H6O3) are broken down into CO2

2.) the energy is captured in ATP & energy carriers

ELECTRON TRANSPORT CHAIN Where? The

mitochondria1.) Energy carriers are

broken apart; the energy released is used to make ATP

2.) O2 bonds with leftover H+ to make H2O

FERMENTATION

AEROBIC VS. ANAEROBIC When O2 is present & all of cellular respiration occurs, 36

ATPs are made from 1 C6H12O6. Aerobic: reactions that require oxygen (the Kreb’s cycle &

electron transport chain)

When there is no O2, only glycolysis occurs & 2 ATPs are made from 1 C6H12O6. Anaerobic: reactions that do not need oxygen (glycolysis)

GLYCOLYSISAdvantage: ATP can be made

without oxygen

Disadvantage: the cell will run out of energy carriers & glycolysis will stop

So…Fermentation occurs!

FERMENTATION Allows glycolysis to continue by converting electron

carriers Anaerobic

Two types: Alcoholic fermentation

Pyruvic acid -> alcohol + CO2 Lactic Acid fermentation

Pyruvic acid -> lactic acid