P HOTOSYNTHESIS Chapter 8

E NERGY & L IFE

E NERGY The 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. UFnY7Y8w

A UTOTROPHS VS. H ETEROTROPHS Organisms that make their own food. AKA: producers Ex: plants Organisms that obtain energy from the food that they eat. AKA: consumers or decomposers Ex: sheep, wolves, mushrooms AutotrophsHeterotrophs

ATP ( ADENOSINE TRIPHOSPHATE ) The main energy storage compound for living things. ATP is NOT good to store 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.

P HOTOSYNTHESIS : A N O VERVIEW

L IGHT & P IGMENT White 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.

S O 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.

E LECTRON C ARRIERS NADP + : can accept 2 high-energy electrons by bonding with an H + ; an “uncharged” energy carrier Similar to ADP NADPH: the “charged” version Similar to ATP

P HOTOSYNTHESIS : A N O VERVIEW ● T HE PROCESS THAT CAPTURES LIGHT ENERGY AND USES IT TO MAKE CARBOHYDRATES ( GLUCOSE ). 6H 2 O + 6CO > C 6 H 12 O 6 + 6O 2 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

W HERE DOES IT TAKE P LACE ? In the chloroplasts.

P HOTOSYNTHESIS 2 Parts: Light dependent reactions Light independent reactions (AKA dark reactions or the Calvin Cycle)

T HE P ROCESS OF P HOTOSYNTHESIS

L IGHT D EPENDENT R EACTIONS Where? The granum 1.) chlorophyll absorbs light 2.) H 2 O is split; O 2 is released 3.) ATP & energy carriers (NADPH) are formed & take the energy (stored in their bonds) to the light independent reaction

L IGHT I NDEPENDENT R EACTIONS / T HE C ALVIN C YCLE Where? The stroma 1.) ATP & NADPH are broken down (ADP & NADP + ) are recycled back to the light dependent reaction 2.) the energy released is used to convert CO 2 to C 6 H 12 O 6

F ACTORS A FFECTING P HOTOSYNTHESIS 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.

C ELLULAR R ESPIRATION & F ERMENTATION Chapter 9

C ELLULAR R ESPIRATION : A N O VERVIEW

CALORIE The amount of energy needed to raise 1g of H 2 O 1○ C. When burned, 1g of glucose releases 3811 calories of heat energy. Food labels show Calories (= 1000 calories).

T WO MORE E LECTRON C ARRIERS NAD + & FAD : “uncharged” energy carriers Similar to ADP NADH & FADH 2 : the “charged” versions Similar to ATP

C ELLULAR R ESPIRATION Releases energy (ATP) by breaking down food in the presence of oxygen. C 6 H 12 O 6 + 6O > 6H 2 O + 6CO 2 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

T HE P ROCESS OF C ELLULAR R ESPIRATION

C ELLULAR R ESPIRATION Three parts: Glycolysis Kreb’s cycle Electron Transport Chain

G LYCOLYSIS Where? The cytoplasm 1.) C 6 H 12 O 6 is split to form 2 pyruvic acids (2C 3 H 6 O 3 ) 2.) the energy is captured in ATP & energy carriers (NADH)

K REB ’ S C YCLE Where? The mitochondria 1.) 2 pyruvic acids (2C 3 H 6 O 3 ) are broken down into CO 2 2.) the energy is captured in ATP & energy carriers (NADH& FADH 2 )

E LECTRON T RANSPORT C HAIN Where? The mitochondria 1.) Energy carriers (NADH & FADH 2 ) are broken apart; the energy released is used to make ATP 2.) O 2 bonds with leftover H + to make H 2 O

F ERMENTATION

A EROBIC VS. A NAEROBIC When O 2 is present & all of cellular respiration occurs, 36 ATPs are made from 1 C 6 H 12 O 6. Aerobic : reactions that require oxygen (the Kreb’s cycle & electron transport chain) When there is no O 2, only glycolysis occurs & 2 ATPs are made from 1 C 6 H 12 O 6. Anaerobic : reactions that do not need oxygen (glycolysis)

G LYCOLYSIS Advantage: ATP can be made without oxygen Disadvantage: the cell will run out of NAD+ & glycolysis will stop So… Fermentation occurs!

F ERMENTATION Allows glycolysis to continue by converting NADH into NAD + Anaerobic Two types: Alcoholic fermentation Pyruvic acid + NADH -> alcohol + CO 2 + NAD + Lactic Acid fermentation Pyruvic acid + NADH -> lactic acid + NAD +