Cellular Energy

Overview The purpose of this unit is to examine how energy is made available to cells to power metabolism. We will learn how energy is captured and stored during photosynthesis in autotrophs, and how energy becomes usable to both autotrophs and heterotrophs through cellular respiration.

Forms of Energy Light Light like the sun. like the sun. Heat Heat like from fire. like from fire. Mechanical: Mechanical: Involves movement Involves movement Ex: mechanical pencil, pencil sharpener, car, bike, etc Ex: mechanical pencil, pencil sharpener, car, bike, etc Chemical: Chemical: Energy is present in chemical bonds of compounds Ex: Sugar-each bond (line) holds a lot of energy. *remember energy can be changed from one form to another, but it cannot be created or destroyed.

Metabolism = A process that involves using energy to build or break down molecules Metabolism = A process that involves using energy to build or break down molecules Photosynthesis and cellular respiration involve making and breaking energy-rich molecules Photosynthesis and cellular respiration involve making and breaking energy-rich molecules All of the chemical reactions that go on inside a cell are known as the cell’s metabolism

Photosynthesis & cellular respiration are biochemical pathways. Photosynthesis & cellular respiration are biochemical pathways. Biochemical pathways Biochemical pathways are a series of reactions where the product of one reaction is the reactant of the next forming a cycle

Review Autotrophs (self feeders)= organisms that can produce their own food using light or chemical energy Autotrophs (self feeders)= organisms that can produce their own food using light or chemical energy Ex: Plants, algae, certain bacteria Heterotrophs (different feeders)= cannot obtain energy from the sun directly so obtain their nutrients by feeding on other organisms Heterotrophs (different feeders)= cannot obtain energy from the sun directly so obtain their nutrients by feeding on other organisms Ex: Animals and Fungi

Since Autotrophs are self feeders, organisms capable of making their own food Since Autotrophs are self feeders, organisms capable of making their own food then… then… 1. Chemoautotrophs: are organisms that use chemicals instead of light energy to produce food. This process is called Chemosynthesis. 1. Chemoautotrophs: are organisms that use chemicals instead of light energy to produce food. This process is called Chemosynthesis. (synthesis means “to make”) Organsims that carry out chemosynthesis are microbes (bacteria) that live far from the sun, such as deep on the ocean floor. Organsims that carry out chemosynthesis are microbes (bacteria) that live far from the sun, such as deep on the ocean floor.

2. Photoautotrophs: are organisms that capture light energy and convert it to chemical energy. This cellular process is photosynthesis. 2. Photoautotrophs: are organisms that capture light energy and convert it to chemical energy. This cellular process is photosynthesis. Organisms that carry out photosynthesis are Plants Photosynthetic Bacteria Some Protists Plants Photosynthetic Bacteria Some Protists (ex. cynobacteria) (ex. Algae) (ex. cynobacteria) (ex. Algae) Ultimate source of energy!

Photosynthesis Overview Happens in: autotrophs Happens in: autotrophs Goal: Converting light energy into chemical energy (glucose) Goal: Converting light energy into chemical energy (glucose) Glucose: carbohydrate monomer Glucose: carbohydrate monomer C 6 H 12 O 6 C 6 H 12 O 6

The energy stored in the The energy stored in the glucose produced by photosynthesis can be transferred to other organisms when the molecules are consumed as food.

Cellular Respiration Overview Happens in: autotrophs AND heterotrophs Happens in: autotrophs AND heterotrophs Goal: convert chemical energy (glucose) into usuable energy (ATP). Goal: convert chemical energy (glucose) into usuable energy (ATP). ATP = adenosine triphosphate ATP = adenosine triphosphate ATP provides cells with energy they need to carry out the activities of life ATP provides cells with energy they need to carry out the activities of life

ATP (Adenine Triphosphate) is used by all types of cells as their basic energy source. is used by all types of cells as their basic energy source. releases energy when the bond between the 2 nd & 3 rd phosphate group is broken releases energy when the bond between the 2 nd & 3 rd phosphate group is broken ATP → ADP + P + energy! ATP → ADP + P + energy! Can be used to: Can be used to: Contract muscles, growth & repair, synthesis of cellular products, ex. Protein synthesis Contract muscles, growth & repair, synthesis of cellular products, ex. Protein synthesis Move things across a cell membrane (Active Transport) Move things across a cell membrane (Active Transport)

hhh Times New Roman (Body) Times New Roman (Body) Adenosine TriphosphateAdenosine Diphosphate  ATP – contains three phosphate groups (tri = three)  ADP – contains two phosphate groups (di = two)

Photosynthesis Needed (Reactants): Needed (Reactants): 1. Light 2. Water 3. Carbon dioxide Given Off (Products): Given Off (Products): 1. Sugars 2. Oxygen

Photosynthesis WRITE THIS EQUATION IN YOUR NOTES

Which organelle does plants use to perform photosynthesis? Chloroplasts Chloroplasts Found in cells of leaves Found in cells of leaves Contains chlorophyll Contains chlorophyll

Chloroplast containing chlorophyll Stoma (Stomata) - small pores on the underside of leaves where gas exchange occurs

Chlorophyll Plants gather the sun's energy with light-absorbing molecules called pigments. Plants gather the sun's energy with light-absorbing molecules called pigments. The plants' principal pigments are called chlorophyll. The plants' principal pigments are called chlorophyll. Chlorophyll does not absorb light well in the green region of the spectrum therefore green light is reflected by leaves (this is why plants look green). Chlorophyll does not absorb light well in the green region of the spectrum therefore green light is reflected by leaves (this is why plants look green).

Pigments Carotenoids Carotenoids Other pigments Other pigments Ex: b-carotene Ex: b-carotene Reflects red/yellow light Reflects red/yellow light Gives carrots/sweet potatoes their color Gives carrots/sweet potatoes their color

The Fall Season Chlorophyll breaks down Chlorophyll breaks down You can see color of other pigments You can see color of other pigments

Chloroplast Vocabulary Thylakoids - disc like photosynthetic membrane found in chloroplasts. Thylakoids - disc like photosynthetic membrane found in chloroplasts. Stroma - Region outside the thylakoid membranes in chloroplasts Stroma - Region outside the thylakoid membranes in chloroplasts Granum- stack of thylakoids Granum- stack of thylakoids - Stack of thylakoids

Photosynthesis is the process by which plants (producers) take in water and CO 2 and using light energy and chlorophyl make 0 2 and glucose OVERVIEW OF PHOTOSYNTHESIS

Photosynthesis 2 steps: 2 steps: Light Dependent reactions Light Dependent reactions Light Independent reactions (Calvin cycle) Light Independent reactions (Calvin cycle) These two chemical reactions work together! Light Dependent Reaction Light Independent Reaction

Photosynthesis Light Dependent reaction: Light Dependent reaction: Occurs in the thylakoid (granum) Occurs in the thylakoid (granum) Must have light light Light Reaction Light Independent Reaction LIGHT REACTION Light Independent Reaction thylakoid (chlorophyll)

Step 1: Light Dependent Reactions H2OH2O O2O2 O2O2 O2O2 O2O2 O2O2 HH How does the O 2 leave the leaf? ENERGY light energy reacts with the chlorophyll water is split by the light energy H is kept for the light independent reaction O 2 is released OH2OH2

What happens to the H + ? NADP + picks up the H + ions (becoming NADPH) and moves them to the stroma for the light independent reaction (Calvin cycle). NADP + picks up the H + ions (becoming NADPH) and moves them to the stroma for the light independent reaction (Calvin cycle). NADPH is a high energy electron carrier ( like a delivery man) provides the energy that converts CO 2 to molecule of sugar NADPH is a high energy electron carrier ( like a delivery man) provides the energy that converts CO 2 to molecule of sugar

Light Dependent Occurs in the thylakoid Occurs in the thylakoid Water is absorbed through roots. Water is absorbed through roots. Sunlight (Light Energy) enters the chloroplast, causing H 2 O molecules to split. Sunlight (Light Energy) enters the chloroplast, causing H 2 O molecules to split. O 2 leaves as a waste product through the stomata. O 2 leaves as a waste product through the stomata.

NADP + picks up the H + ions (becoming NADPH) and moves them to the stroma for the light independent reaction (Calvin cycle) NADP + picks up the H + ions (becoming NADPH) and moves them to the stroma for the light independent reaction (Calvin cycle) ATP( ENERGY) helps to fuel the light independent reaction, or the Calvin Cycle ATP( ENERGY) helps to fuel the light independent reaction, or the Calvin Cycle

Photosynthesis Light Independent reactions (aka Calvin cycle): Light Independent reactions (aka Calvin cycle): Occurs in the stroma Occurs in the stroma Occurs in the light and dark Light Reaction Light Independent Reaction Light Reaction LIGHT INDEPENDENT REACTION stroma (liquid)

Step 2: Light Independent Reactions AKA: CALVIN CYCLE AKA: CALVIN CYCLE CO 2 H C 6 H 12 O 6 How does CO 2 enter the plant? H from the water split in the light reaction is present CO 2 enters the chloroplast the reactants H and CO 2 combine H H + CO 2 glucose is the product Other carbohydrates besides glucose may be made in photosynthesis

Light Independent Overview Carbon dioxide from the atmosphere enters the stoma Carbon dioxide from the atmosphere enters the stoma Light Independent Reaction takes place in stroma Light Independent Reaction takes place in stroma H + breaks off from NADPH H + breaks off from NADPH NADP + returns to the Light Dependent Reaction (Thylakoid) NADP + returns to the Light Dependent Reaction (Thylakoid) Carbon dioxide becomes “fixed” with the H + producing the glucose molecule C 6 H 12 O 6. Carbon dioxide becomes “fixed” with the H + producing the glucose molecule C 6 H 12 O 6. ATP helps to fuel the light independent reaction. ATP becomes ADP and returns to the light dependent reaction. ATP helps to fuel the light independent reaction. ATP becomes ADP and returns to the light dependent reaction.

Photosynthesis Review Light reactions: H 2 O split into H 2 + O Light independent reactions: H + CO 2 = C 6 H 12 O 6 H2OH2O Light Reaction Light Independent Reaction CO 2 C 6 H 12 O 6 O2O2 chlorophyll H

Photosynthesis Formula How would this be written as a chemical equation? What goes in? (the reactants) What comes out? (the products) H2OH2O Light Dependent Reaction Light Independent Reaction CO 2 C 6 H 12 O 6 O2O2 chlorophyll H2OH2OCO 2 C 6 H 12 O 6 O2O2 light

Photosynthesis Formula What’s wrong with this equation? The number of atoms is not equal on both sides of the equation. Balance the equation so that the number of atoms of each element is equal on both sides. H2OH2OCO 2 C 6 H 12 O 6 O2O2 one carbon atom reactant 6 carbon atoms product 6 66(1)

Comparing Photosynthesis and Respiration CO 2 + H Energy (Light)  C 6 H 12 O 6 + O 2 C 6 H 12 O  Energy (ATP) + CO 2 + H 2 0 IMPORTANT COMPARISON!: the reactants of one reaction are the products of the other reaction!

Factors Affecting Photosynthesis 1. Water  A shortage of water can slow or even stop photosynthesis. 2. Temperature  Photosynthesis depends on enzymes that function best between 0°C and 35°C. 3. Intensity of Light  Increasing light intensity increases the rate of photosynthesis...but a plant will reach a maximum rate.

Light-Dependent Reactions Takes place within the thylakoid membranes Takes place within the thylakoid membranes Requires light Requires light Requires: Water, ADP, and NADP + Requires: Water, ADP, and NADP + Produce: Oxygen, ATP, and NADPH Produce: Oxygen, ATP, and NADPH

Electron Carriers within the Light Dependent reaction Inside the thylakoid, electrons within the chlorophyll become “excited” (gain energy) from the sunlight. Now that they have all this energy they require a carrier molecule : NADP+. Inside the thylakoid, electrons within the chlorophyll become “excited” (gain energy) from the sunlight. Now that they have all this energy they require a carrier molecule : NADP+.

NADP + NADP + NADP + As soon as this carrier molecule NADP+ accepts the energy (from the electrons) it converts the NADP + into NADPH. As soon as this carrier molecule NADP+ accepts the energy (from the electrons) it converts the NADP + into NADPH. This transfer of electrons and energy is called the Electron Transport Chain (ETC) This transfer of electrons and energy is called the Electron Transport Chain (ETC)

Light Dependent Reactions The sunlight breaks each water molecule into : The sunlight breaks each water molecule into : electrons electrons H + ions (released into thylakoid membrane) H + ions (released into thylakoid membrane) Oxygen atoms (released into the air) Oxygen atoms (released into the air)

Light Dependent Reactions As electrons are passed from chlorophyll to NADP +, more hydrogen ions are pumped across the membrane. As electrons are passed from chlorophyll to NADP +, more hydrogen ions are pumped across the membrane. Inside of the membrane fills up with positively charged hydrogen ions. Inside of the membrane fills up with positively charged hydrogen ions. Outside of thylakoid membrane becomes negatively charged. Outside of thylakoid membrane becomes negatively charged. The difference in charges across the membrane provides the energy to make ATP. The H + ions are important! The difference in charges across the membrane provides the energy to make ATP. The H + ions are important!

Light Dependent Reactions ATP Synthase - Large protein/enzyme that uses energy from H + ions to bind ADP and a phosphate group together to produce ATP. ATP Synthase - Large protein/enzyme that uses energy from H + ions to bind ADP and a phosphate group together to produce ATP. Spans the thylakoid membrane and allows H + ions to pass through it. Spans the thylakoid membrane and allows H + ions to pass through it. Overall: Produce oxygen gas and convert ADP and NADP + into the energy carriers ATP and NADPH. Overall: Produce oxygen gas and convert ADP and NADP + into the energy carriers ATP and NADPH.

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The Light-Independent Reactions (Calvin Cycle) Takes place in the stroma Takes place in the stroma Uses ATP and NADPH from the light- dependent reactions to produce high-energy sugars. Uses ATP and NADPH from the light- dependent reactions to produce high-energy sugars.

Calvin Cycle Uses six molecules of carbon dioxide to produce one 6-carbon glucose molecule. Uses six molecules of carbon dioxide to produce one 6-carbon glucose molecule. Energy for this conversion comes from ATP and high-energy electrons from NADPH. Energy for this conversion comes from ATP and high-energy electrons from NADPH.