PHOTOSYNTHESIS. Chapter 8

Transcription

1 PHOTOSYNTHESIS Chapter 8

2 ENERGY & LIFE

3 ENERGY 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. Y8w -wvg

4 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.

5 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.

6 PHOTOSYNTHESIS: AN OVERVIEW

7 LIGHT & PIGMENT 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.

8 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

9 ENERGY CARRIERS NADP + : an uncharged energy carrier Similar to ADP NADPH: the charged version Similar to ATP

10 PHOTOSYNTHESIS: AN OVERVIEW THE PROCESS THAT CAPTURES LIGHT ENERGY AND USES IT TO MAKE CARBOHYDRATES (GLUCOSE). sunlight 6H O + 6CO > C H O + 6O Water: Comes in through the roots Carbon Dioxide: Comes in from the air Glucose: Stored as chemical energy Oxygen: leaves back to the air

11 FACTORS AFFECTING PHOTOSYNTHESIS 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.

12 THE PROCESS OF PHOTOSYNTHESIS

13 WHERE DOES IT TAKE PLACE? In the chloroplasts.

14 PHOTOSYNTHESIS 2 Parts: Light dependent reactions Light independent reactions (AKA the Calvin Cycle)

15 LIGHT DEPENDENT REACTIONS 1.) chlorophyll absorbs light 2.) H 2 O is split; O 2 is released 3.) energy is transferred to energy carriers (ATP & NADPH), which go to the Calvin cycle

16 LIGHT INDEPENDENT REACTIONS/ 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 CO 2 to C 6 H 12 O 6

17 CELLULAR RESPIRATION & FERMENTATION Chapter 9

18 CELLULAR RESPIRATION: AN OVERVIEW

19 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).

20 TWO MORE ELECTRON CARRIERS NAD + & FAD: uncharged energy carriers Similar to ADP NADH & FADH 2 : the charged versions Similar to ATP

21 CELLULAR RESPIRATION 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 Oxygen: taken in from the air Water: released as waste Carbon Dioxide: released into the air

22 THE PROCESS OF CELLULAR RESPIRATION

23 CELLULAR RESPIRATION Three parts: Glycolysis Kreb s cycle Electron Transport Chain

24 GLYCOLYSIS 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

25 KREB S CYCLE 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

26 ELECTRON TRANSPORT CHAIN Where? The mitochondria 1.) Energy carriers are broken apart; the energy released is used to make ATP 2.) O 2 bonds with leftover H + to make H 2 O

27 FERMENTATION

28 AEROBIC VS. ANAEROBIC 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)

29 GLYCOLYSIS Advantage: ATP can be made without oxygen Disadvantage: the cell will run out of energy carriers & glycolysis will stop So Fermentation occurs!

30 FERMENTATION Allows glycolysis to continue by converting electron carriers Anaerobic Two types: Alcoholic fermentation Pyruvic acid -> alcohol + CO 2 Lactic Acid fermentation Pyruvic acid -> lactic acid