8. Photosynthesis

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WHAT DO CELLS USE ENERGY FOR ? ACTIVE TRANSPORT Na+ - K + PUMP Endocytosis Exocytosis Energy and Life

WHAT DO CELLS USE ENERGY FOR ? Movement Synthesis of biomolecules Reproduction Meiosis: Cilia: Replication: Transcription: Translation:

ATP ONE SPECIAL KIND of NUCLEOTIDE is used by cells to store and transport ENERGY

CELLS USE ATP TO STORE and RELEASE ENERGY ATP = __________________________ Adenosine triphosphate ____ PHOSPHATE GROUPS 3

ATP can change into ADP ADP = __________________________ Adenosine diphosphate ____ PHOSPHATE GROUPS 2

ATP → ____ + ____ + ATP releases energy stored in a high energy chemical bond by removing the phosphate and becoming ADP ADP

ADP + ___ + ________ → ___ The energy to do this comes from ____________ like _____________ Cells ________ energy by adding the phosphate back on to ADP to make ATP. ATP It’s like recharging the battery ! STORE FOODSGLUCOSE

_____________ can make their own food using energy from sunlight. Ex: Green plants, a few bacteria Autotrophs

__________________ get energy by consuming other organisms Ex: Animals, fungi, most bacteria Heterotrophs

Photosynthesis

a metabolic pathway that converts light energy into chemical energy. is the process by which plants, some bacteria, and some protists use the energy from sunlight to produce sugar.

Photosynthesis

Method of converting sun energy into chemical energy usable by cells Autotrophs: self feeders, organisms capable of making their own food – Photoautotrophs: use sun energy e.g. plants photosynthesis-makes organic compounds (glucose) from light – Chemoautotrophs: use chemical energy e.g. bacteria that use sulfide or methane chemosynthesis-makes organic compounds from chemical energy contained in sulfide or methane

Photosynthesis Photosynthesis takes place in specialized structures inside plant cells called chloroplasts – Light absorbing pigment molecules e.g. chlorophyll

Chloroplasts containing chlorophyll.

Chloroplast

Chlorophyll

Visible Spectrum

Photosynthetic Pigments

6H 2 O + 6CO 2  C 6 H 12 O 6 + 6O 2 (water) + (carbon dioxide) + (light)  (sugar) + (oxygen)

24 Leaves and Photosynthesis

How Leaves Work

LIGHT-DEPENDENT REACTIONS See an animation about the ELECTRON TRANSPORT CHAIN Pearson Education Inc; Publishing as Pearson Prentice Hall SEE A MOVIE ATP SYNTHASE IN ACTION

27 Light Reactions: Noncyclic Electron Pathway

28 Light Reactions:

Light-dependent Reactions Overview: light energy is absorbed by chlorophyll molecules-this light energy excites electrons and boosts them to higher energy levels. They are trapped by electron acceptor molecules that are poised at the start of a neighboring transport system. The electrons “fall” to a lower energy state, releasing energy that is harnessed to make ATP

Energy Shuttling Recall ATP: cellular energy-nucleotide based molecule with 3 phosphate groups bonded to it, when removing the third phosphate group, lots of energy liberated= superb molecule for shuttling energy around within cells. Other energy shuttles-coenzymes (nucleotide based molecules): move electrons and protons around within the cell NADP+, NADPH NAD+, NADP FAD, FADH 2

Light-dependent Reactions Photosystem: light capturing unit, contains chlorophyll, the light capturing pigment Electron transport system: sequence of electron carrier molecules that shuttle electrons, energy released to make ATP Electrons in chlorophyll must be replaced so that cycle may continue-these electrons come from water molecules, Oxygen is liberated from the light reactions Light reactions yield ATP and NADPH used to fuel the reactions of the Calvin cycle (light independent or dark reactions)

Calvin Cycle (light independent or “dark” reactions) ATP and NADPH generated in light reactions used to fuel the reactions which take CO 2 and break it apart, then reassemble the carbons into glucose. Called carbon fixation: taking carbon from an inorganic molecule (atmospheric CO 2 ) and making an organic molecule out of it (glucose) Simplified version of how carbon and energy enter the food chain

35 Calvin Cycle Reactions: Overview of C3 Photosynthesis A cyclical series of reactions Utilizes atmospheric carbon dioxide to produce carbohydrates Known as C3 photosynthesis Involves three stages: Carbon dioxide fixation Carbon dioxide reduction RuBP Regeneration

CALVIN CYCLE (also called _________________________) ____________ require ____________ Happens in _________ between thylakoids NADPH donates _______________ ATP donates _________________ CO 2 donates ______________ to make __________ LIGHT LIGHT INDEPENDENT ENERGY STROMA Hydrogen + electrons Carbon & oxygen GLUCOSE DOES NOT

CO 2 Enters the Cycle Energy Input 5-Carbon Molecules Regenerated Sugars and other compounds 6-Carbon Sugar Produced Calvin Cycle

Photosynthesis includes of take place in takes place in uses to produce use Section 8-3 Concept Map

Photosynthesis includes of take place in takes place in uses to produce use Light- dependent reactions Calvin cycle Thylakoid membranes StromaNADPH ATP Energy from sunlight ATPNADPHO2O2 Chloroplasts High-energy sugars Section 8-3 Concept Map

40 Photosynthesis Overview

Harvesting Chemical Energy So we see how energy enters food chains (via autotrophs) we can look at how organisms use that energy to fuel their bodies. Plants and animals both use products of photosynthesis (glucose) for metabolic fuel Heterotrophs: must take in energy from outside sources, cannot make their own e.g. animals When we take in glucose (or other carbs), proteins, and fats-these foods don’t come to us the way our cells can use them