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PHOTOSYNTHESIS CAPTURING ENERGY Chapter 6. ENERGY  Autotrophs – Organisms that make their own food from inorganic substances and energy (ATP). –Use photosynthesis.

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Presentation on theme: "PHOTOSYNTHESIS CAPTURING ENERGY Chapter 6. ENERGY  Autotrophs – Organisms that make their own food from inorganic substances and energy (ATP). –Use photosynthesis."— Presentation transcript:


2 ENERGY  Autotrophs – Organisms that make their own food from inorganic substances and energy (ATP). –Use photosynthesis – converting light energy into chemical energy –Store chemical energy as organic compounds (like carbohydrates) –EX: plants, algae, and some bacteria

3 PHOTOSYNTHESIS 6CO 2 +6H 2 O+lightC 6 H 12 O 6 +6O 2  A biochemical pathway that involves a complex series of chemical reactions  The product of this reaction is consumed in the next reaction  Process supports virtually all life on Earth

4 Understanding Photosynthesis  1. Jan Van Helmont (1600’s) – set up an experiment to understand how a small seed grew to a large tree –Concluded that plants need water to grow.  2. Joseph Priestly (1771) – set up an experiment with a candle…he discovered a candle in a jar died out but a candle in a jar with a plant continued burning.  3. Jan Ingenhousz (1779)– found that the plant/candle experiment only worked when the plant was exposed to sunlight –Concluded: light is necessary for plants to produce oxygen

5 The Nature of Light  Visible Spectrum – the separation of white light into different colors (wavelengths)  PIGMENT – a molecule that absorbs certain wavelengths of light and reflects or transmits others

6 Chloroplasts- organelle that contains chlorophyll and other pigments; site of photosynthesis  Contains: –Thylakoids – disk-shaped structures that contain photosynthetic pigments –Grana – Stacks of thylakoids (resemble stacks of pancakes) –Stroma – Solution surrounding the thylakoids –Chlorophyll- light collecting pigment located on the thylakoid disks

7 CHLOROPHYLL and PIGMENTS  The most common and important photosynthetic pigments in plants and algae.  Absorbs violet, blue, and red lights.  Reflect and Transmit Green light – giving plants their GREEN color. –Chlorophyll a – primary photosynthetic pigment –Accessory Pigments – Chlorophyll b and carotenoids


9 LIGHT REACTIONS  Initial reactions of photosynthesis  Begins with absorption of light in chloroplasts (in the thylakoids) to create chemical energy (ATP and NADPH)

10 Light rxn. animation Water molecules are split, creating electrons, protons, and oxygen as a byproduct

11 Light rxn. Cont.  Reactants: H 2 O + Sunlight  Products: O 2 + ATP + NADPH (energy carrier) + H + (used later)

12 Chemiosmosis  The synthesis of ATP  Occurs when there is a concentration gradient of protons across the thylakoid membrane  ADP  ATP

13 CALVIN CYCLE  Second set of reactions in photosynthesis  Is not dependent on light  Occurs in the stroma (liquid area of the chloroplast) when ATP and NADPH are present  Makes stored energy (in the form of carbs) that the plant can use

14 How is this done?  Carbon fixation: carbon atoms are bonded (“fixed”) into organic compounds  aided by enzymes  Reactants: CO 2 + ATP + NADPH + H +  Products: O 2 + C 6 H 12 O 6

15 Animation



18 The rate of photosynthesis varies:  1. light intensity  2. amount of CO 2  3. temperature


20 Notebook quiz 1) Write the equation for photosynthesis out in words? 2) Where in the chloroplast do the light reactions occur? 3) What are the products of the light reaction? 4) What are the products of the Calvin Cycle? 5) What is the primary photosynthetic pigment in plants?

21 ALTERNATIVE PATHWAYS STOMATA – small pores in leaves of plants C4 Plants – close stomata during hot parts of the day (still able to produce carbohydrates) EX: corn, sugar cane, crabgrass CAM Plants – open stomata at night and close them during the day…producing organic compounds at night EX: cactus, pineapples


23 CELLULAR RESPIRATION  C 6 H 12 O 6 + 6O 2 6CO 2 +6H 2 O+ energy(ATP)  The complex process in which cells make ATP by breaking down organic compounds  Heterotrophs – Organisms that obtain energy from eating autotrophs or other heterotrophs

24 GLYCOLYSIS  The beginning of cellular respiration  Glucose is converted into 2 molecules of pyruvic acid  Produces very little ATP and NADH glucosepyruvic acid

25 GLYCOLYSIS PRODUCTION  Glycolysis USES 2 ATP molecules to start the pathway  Glycolysis MAKES 4 ATP molecules at the end of glycolysis  Therefore, glycolysis produces: –Net total of 2 ATP –NADH –2 molecules of Pyruvic Acid

26 –With Oxygen…glycolysis is followed by AEROBIC RESPIRATION to produce more ATP Examples of aerobic exercise: long distance activities –Without Oxygen…glycolysis is followed by FERMENTATION (anaerobic respiration) producing no ATP Examples of anaerobic exercise: sprinting

27 FERMENTATION  Without Oxygen…Glycolysis goes to Anaerobic Respiration  Does not produce ATP  Recycles NAD+ from NADPH to keep glycolysis going  2 most common fermentation pathways: –LACTIC ACID FERMENTATION –ETHYL ALCOHOL FERMENTATION

28 LACTIC ACID FERMENTATION  Converts pyruvic acid into lactic acid  Helps produce some foods ex) yogurts and cheeses  Also occurs in your muscle cells during very strenuous exercise ex) sprinting  As lactic acid accumulates…it reduces the ability of the muscle cells to contract…resulting in fatigue, pain, and cramping

29 ALCOHOLIC FERMENTATION  Used by some plant cells and unicellular organisms  Converts pyruvic acid into ethyl alcohol  Used in the wine and beer industries and in the making of breads

30 AEROBIC RESPIRATION  Occurs when Oxygen is present in the cell  Pyruvic acid is converted to CO2 and water  Produces large amounts of ATP  Takes place in the mitochondria  2 major stages: The Kreb’s Cycle Electron Transport Chain


32 THE KREB’S CYCLE  Occurs in the mitochondrial MATRIX (space inside the inner membrane of the mitochondria)  Biochemical pathway that breaks down acetyl CoA, and produces CO 2, hydrogen atoms, and ATP  1 Glucose molecule gives 2 cycles of the Kreb’s cycle and produces: –6 NADH –2 FADH 2 –2 ATP –4 CO 2

33 ELECTRON TRANSPORT CHAIN  Second stage of aerobic respiration…occurs along the many folds (cristae) of the mitochondria  4 NADH from Glycolysis produce a total of 12 ATP  6 NADH from Kreb’s produce a total of 18 ATP  2 FADH 2 from Kreb’s produce a total of 4 ATP  Electron Transport Chain Produces a TOTAL of 34 ATP



36 Why do leaves change color in the fall?  How do annuals and perennials survive winter?  Why do deciduous trees loose their leaves and evergreens do not loose their needles?  Why do the leaves fall from the trees in autumn?  How and why do the leaves separate from the tree?  What is anthocyanin?  Name other pigments that appear in leaves after the chlorophyll disappears.  Where is the best place to see the color change? Why?

37 Photosynthesis Comic Directions  Create a minimum 6 slide comic strip summarizing the process of photosynthesis.Be sure to include the reactants and products of the light and dark reactions.

38 Cellular Respiration Poster!  Design a poster summarizing all important parts of the stages of aerobic and anaerobic cellular respiration. –Show how all of the processes are related –Be creative –Be prepared to show your poster to the rest of the class and explain its contents

39 Notebook Quiz  Distinguish between autotrophs and heterotrophs.  What are the (3) products of glycolysis?  After glycolysis, what determines the next step?  What type of fermentation occurs in animal cells?  What are the 2 steps of aerobic respiration?  How many ATP are produced in cellular respiration?

40 Notebook Quiz 1. What is the primary photosynthetic pigment in plants? 2. In photosynthesis, where do the light reactions occur? Where does the Calvin Cycle occur? 3. What is the chemical energy produced in photosynthesis? 4. What molecule made in photosynthesis is “burned” in cellular respiration? 5. Distinguish between autotrophs and heterotrophs. 6. What are the 3 products of glycolysis? 7. After glycolysis, what determines the next step?

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