Energy What is Energy Energy is the ability
Energy
What is Energy � Energy is the ability to do work � This can be thought of on the macro-level, (we need energy to play sports) or on the micro-level (our cells need energy to function) � Living things use chemical fuels to supply energy � Energy is acquired by the breaking of chemical bonds � One of the most important chemical fuels is ATP
ATP � Adenosine triphosphate � Basic energy source used by all types of cells � This molecule consists of: � Adenine � 5 -carbon sugar called ribose � 3 phosphate groups
ATP � Energy is stored in ATP when a phosphate group is added to adenosine diphosphate (ADP). � Energy is released when the bond is broken between the second and third phosphate groups � Think of ADP as a rechargeable battery that is low on juice and ATP as a recharged battery ready to be used � ATP is used throughout the cell � It is not great for storing large amounts of energy, so, the cell makes creates ATP as it is needed.
Where do we get energy? � How organisms acquire the energy (food) to produce energy (ATP) is divided into two classes: Autotroph and Heterotroph
Autotroph � These are your energy producers � Organisms that make their own food � They do this by harnessing the energy from sunlight and using it to break chemical bonds, powering the process of photosynthesis � Plants, algae and some bacteria fall into this category
Heterotroph � Organisms that obtain food by consuming other organisms � These are also known as consumers � The amount of energy that is passed from one trophic level to the next is only 10% of the available energy. � Organisms at the top of the food chain have to consume a lot organisms below them to acquire acceptable amounts of energy.
Photosynthesis
Photosynthesis � Process by which plants use energy to produce high-energy carbohydrates � Carbohydrates are great for storing energy.
Carbohydrates What is the chemical formula of this carbohydrate?
Carbohydrates • This is Glucose • The chemical formula for glucose is C 6 H 12 O 6 • Glucose is a simple sugar
Carbohydrates What is the chemical formula of this carbohydrate?
Carbohydrates • This is Fructose • The chemical formula for glucose is C 6 H 12 O 6 • Glucose is a simple sugar
Carbohydrates What is the chemical formula of this carbohydrate?
Carbohydrates • • This Sucrose C 12 H 22 O 11 You have all tasted Sucrose It is found in every plant, however, only two contain it in high enough concentrations for economic recovery
Carbohydrates � What do plants do with these carbohydrates they have created? � First, the molecules join together to form polymers � These polymers either store the energy for later use, or are put to use within the cell’s organelles
Carbohydrates � Glucose can be linked together to form starch � � Stores energy It is also turned into cellulose � Makes up cell wall
Cellulose Microfibrils of the cell wall Filter paper cross section
Where does this all take place? � Plants have a unique organelle called the chloroplast � Inside these chloroplasts are pigments that absorb the sun’s energy � Chlorophyll is the most common pigment � It is definitely the strongest. � It absorbs light in the blue-violet and regions of the visible spectrum � It does not absorb green light, however, and it is therefore reflected, giving plants a green look.
Pigments � Plants do have other pigments � Red (anthocyanins), yellow (xanthophyll) and orange (carotene) pigments absorb lights in other regions of the visible spectrum � In the fall, as temperatures drop, chlorophyll molecules break down � As a result, light is reflected off the red and orange pigments and voila, we have fall colors.
One more fun fact � When chloroplasts die, they fluoresce. � Generally this happens too quickly for us to observe. � In banana skins, chloroplasts are constantly dying. Their death is slow and drawn out, enabling us to observe their fluorescence.
Chloroplasts � Only found in plant cells � Contain multiple saclike membranes called thylakoids � Thylakoids are interconnected and arranged in stacks known as granna (singular is granum) � � Chlorophyll is located in the thylakoids Stroma is the fluid portion of the chloroplast outside thylakoids
Take a few minutes and draw a chloroplast in your lab books. Include the: outer membrane inner membrane Thylakoid Granum Stroma
High-Energy Electrons https: //www. youtube. com/watch? v=II 4 Ueb. N 1 Dxw
High-Energy Electrons � Chlorophyll produces high-energy electrons � These require special carriers to transport them to other molecules � NADP+ (nicotinamide adenine dinucleotide phosphate) � NADP+ takes two electrons plus one H+ ion turning the compound into NADPH
Photosynthesis � Photosynthesis is complex and has many moving parts � It can be summarized into one equation/sentence Photosynthesis uses the energy of the sunlight to convert carbon dioxide and water (reactants) into high-energy sugars and oxygen (products)” � Two parts to photosynthesis; light-dependent and light-independent
Light-Dependent Reactions � Require light and light-absorbing pigments to take place � Occurs in the thylakoid � Use energy from the sun and electrons/hydrogen ions from water to make high energy ATP and NADPH � Oxygen is the byproduct of this reaction
Light-Dependent Reactions � Rely on the presence of photosystems � Photosystems are proteins found on the membrane of the thylakoid � Take in sunlight and add energy to electrons � Electrons are then passed through electron carriers in the membrane � There are two photosystems in the process
Light-Dependent Reactions � Photosystem II � Named in order of discovery, photosystem II is the first protein in the process. � It absorbs light and energizes electrons before sending them down the electron transport chain � The electron transport chain is a system of carrier proteins along the membrane � They use the energy from electrons passing through to pump H+ ions inside thylakoid
Light-Dependent Reactions � Photosystem I is next � This protein re-energizes the electrons that have passed through the chain thus far. � Once energized, the electrons are moved to another electron transport chain where they are combined with the special carrier, NADP+ and a H+ ion to form NADPH
Light-Dependent Reactions � H+ ions are accumulated in the thylakoid as water molecules are broken up or as electrons are moved along the electron transport chain � The difference in concentration of H+ ions inside vs outside thylakoid powers the production of ATP � H+ can enter through carrier proteins, it cannot exit through them � ATP Synthase is a pump specific to H+ ions � As H+ ions are pumped out, ATP synthase spins, producing enough energy to add a phosphate group to the ADP.
ATP Synthase
Light-Dependent Reactions � A recap of all that info � Light-dependent reactions breaks down water using the energy from sunlight to pump electrons along the membrane of the thylakoid in order to energize the compounds ADP and NADP+ turning them into ATP and NADPH. � Oxygen is released during this process.
Summary � Draw a diagram of a light-dependent reaction. � Be as thorough as you can labeling as many parts as you can • • • Thylakoid membrane Thylakoid Stroma Photosystem II Electron Carriers Photosystem I ATP Synthase H+ ions H 20 Molecules Light Energy • • • O 2 molecules NADP+ NADPH ADP ATP Electrons
Light-independent Reaction � Also known as the Calvin Cycle � The other step of photosynthesis � Does not require light � Occurs in the Stroma � Uses ATP and NADPH to make high-energy sugars out of carbon dioxide from the air
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