PHOTOSYNTHESIS Chapter 8
ENERGY & LIFE
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. http://www.youtube.com/watch?v=qybufny7 Y8w 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: AN OVERVIEW
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.
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 ENERGY AND USES IT TO MAKE CARBOHYDRATES (GLUCOSE). sunlight 6H O + 6CO ----------> C H O + 6O 2 2 6 12 6 2 Water: Comes in through the roots Carbon Dioxide: Comes in from the air Glucose: Stored as chemical energy Oxygen: leaves back to the air
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. http://www.youtube.com/watch?v=lgypeeabous
THE PROCESS OF PHOTOSYNTHESIS
WHERE DOES IT TAKE PLACE? In the chloroplasts.
PHOTOSYNTHESIS 2 Parts: Light dependent reactions Light independent reactions (AKA the Calvin Cycle)
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
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
CELLULAR RESPIRATION & FERMENTATION Chapter 9
CELLULAR RESPIRATION: AN OVERVIEW
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).
TWO MORE ELECTRON CARRIERS NAD + & FAD: uncharged energy carriers Similar to ADP NADH & FADH 2 : the charged versions Similar to ATP
CELLULAR RESPIRATION Releases energy (ATP) by breaking down food in the presence of oxygen. C 6 H 12 O 6 + 6O 2 ----------> 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
THE PROCESS OF CELLULAR RESPIRATION
CELLULAR RESPIRATION Three parts: Glycolysis Kreb s cycle Electron Transport Chain
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
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
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
FERMENTATION
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)
GLYCOLYSIS Advantage: 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 + CO 2 Lactic Acid fermentation Pyruvic acid -> lactic acid