How cells acquire energy

 What is a heterotroph?  What is an autotroph?  What is the main source of energy?  What is energy?

 Stored energy  Based on position of an object

 Energy that moving objects/particles possess

 Energy in the form of light

 Continual input of solar energy into Earth’s atmosphere  Almost 1/3 is reflected back into space  Of the energy that reaches Earth’s surface, about 1% is intercepted by photoautotrophs (organisms that capture light energy to make food)  This means that only 10% of the energy is passed to each trophic level

Shortest Gamma rays wavelength X-rays UV radiation Visible light Infrared radiation Microwaves LongestRadio waves wavelength

 Light  Sunlight is perceived as “white” light  Actually is a mixture of wavelengths  Light absorbing pigments (CHLOROPHYLL) gather the sun’s energy

Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyll absorbs light very well in the blue and red regions of the visible spectrum. It does not absorb green which is why the plant is green. –Light AbsorptionLight Absorption –

Organelles of photosynthesis

 Light-catching part of molecule often has alternating single and double bonds  These bonds contain electrons that are capable of being moved to higher energy levels by absorbing light

Main pigments in most photoautotrophs Wavelength absorption (%) Wavelength (nanometers) chlorophyll b chlorophyll a

Chlorophylls a and b- reflect green Carotenoids-reflect red, yellow, orange  Carotenes - pure hydrocarbons  Xanthophylls - contain oxygen Anthocyanins-reflects red to purple (flowers) Phycobilins-reflects red to purple (flowers)

 Bacteria  Pigments in plasma membranes  Plants  Pigments embedded in thylakoid membrane system  Pigments and proteins organized into photosystems  Photosystems located next to electron transport systems

Chloroplast Structure

 Contain pigments that absorb light  Chlorophyll is the main one  Light dependent reaction occurs here

 Location of the Calvin cycle  13 reactions in three phases  13 enzymes catalize the steps

Photosynthesis: An overview

Photosynthesis Equation: light 6CO 2 +6H 2 O  C 6 H 12 O 6 +6O 2

 Energy also comes in chemical compounds.  Adenosine Triphosphate – ATP  Consists of a nitrogen-containing compound (adenine), a 5-C sugar (ribose), & THREE phosphate groups  Adenosine Diphosphate – ADP  Consists of a nitrogen-containing compound (adenine), a 5-C sugar (ribose), & TWO phosphate groups

PhosphateAdenineRibose

 Stores Energy for all types of cells.  Organelles can move throughout cell.  Active Transport  Sodium-Potassium pump

 ATP only stores small quantities of energy.  Only allows a few seconds of activity.  Glucose stores 90 times as much energy.  Possible Solution???  Store glucose and use it to make ATP.

 Another energy carrying molecule NADP + + H + + 2e -  NADPH Energy carrier energystored energy NADPH  NADP + + H + + 2e - Stored energy Energy carrier released energy

LIGHT Water O2O2 Sugars CO 2 Chloroplast Light- Dependent Reactions Calvin Cycle NADPH ATP ADP + P NADP +

 Require light  Produce oxygen gas  Convert ADP and NADP+ into energy carriers ATP and NADPH

It is strongly recommended that you look at your book diagrams before the test and read your notes at the same time!

 When a pigment molecule absorbs a photon, one of the pigment’s electrons jumps to an energy level farther from the nucleus, making it have an ‘excited’ state  Both photosystems capture solar power

 Chlorophyll a is called P680  Chlorophyll a is called P700 You don’t need to know this, but it has to do with the wavelengths of the colors they absorb. 680 nm is the red wavelength and 700 nm is the far red wavelength Extra Info…

 Photosystem II  Water molecules are split, allows ADP to become ATP again

 Light energy is converted to chemical energy of ATP and NADPH  Electrons removed from water pass from photosystem II to photosystem I to NADP+, providing energy for the synthesis of ATP

 Plants use energy that ATP and NADPH contain to build high-energy compounds that can be stored for a long time  Produces high-energy sugars  Light-independent reaction  Sugar factory within the chloroplast

1. Carbon fixation—enzyme called rubisco combines with Carbon Dioxide, and splits 2. Reduction—two chemical reactions consume energy from ATP and oxidize NADPH. Produces energy rich three carbon sugars 3. G3P released—Net product of photosynthesis— used to make glucose 4. Regeneration of RuBP—ATP rearranges G3P to form more RuBP for step 1 to repeat FOR ONE G3P MOLECULE, THE CALVIN CYCLE CONSUMES NINE ATP AND SIX NADPH, PROVIDED BY THE LIGHT REACTIONS. IT TURNS SIX TIMES TO MAKE ONE GLUCOSE MOLECULE.

 Water  Shortage of water would slow/stop photosynthesis  Temperature  Enzymes are necessary  Ideal temps (0-35 degrees C)  Light intensity

 Oxygen  Carbon Dioxide and Moderation of Global Warming  Other?