4.2 Overview of Photosynthesis

Transcription

1 KEY CONCEPT The overall process of photosynthesis produces sugars that store chemical energy. Radiant Energy Chemical Energy

2 A. Organisms are classified according to how they obtain energy. 1. Autotroph/Producers 1) Producers make their own source of chemical energy. 2) Plants use photosynthesis and are producers. 3) Photosynthesis captures energy from sunlight to make sugars. NOTE: Some organisms live in places that never get sunlight.

3 2. Heterotrophs/Consumers 1). Energy is obtained from food instead of sunlight or inorganic substances.

4 Autotroph or Heterotroph Are You Ready For The Challenge?

5 EVERGREEN TREES

6 PENGUINS

7 EARTH WORMS

8 JELLYFISH

9 VENUS FLY TRAPS

10 PALM TREE

11 SEAL

12 Picture Plant Carnivorous Plant

13 MONKEYS

14 GIRAFFES

15 Venus Fly Trap

16 B. Metabolism 1. The sum of all of the chemical reactions in a cell. 2. Two Types: 1) Anabolic: Simpler substances are combined to form more complex molecules a. Requires energy from catabolic pathways. b. Energy is in the form of ATP. 2) Catabolic: The break down of more complex organic molecules into simpler substances a. Releases energy used to drive chemical reactions

17 Anabolic or Catabolic ABCD + H2O A + B + C + D

18 Autotroph or Heterotroph

19 Anabolic or Catabolic A + B + C + D ABCD + H2O

20 Anabolic or Catabolic Digestion of food.

21 Autotroph or Heterotroph

22 Anabolic or Catabolic Making a protein by combining amino acids.

23 C. Photosynthesis SUNLIGHT 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 In photosynthesis, is the formation of glucose demonstrating a(n) anabolic or a catabolic chemical reaction?

24 Purpose for Photosynthesis Transforms light energy into chemical energy (in the form of organic compounds) through a series of reactions. Radiant Energy Chemical Energy

25 Requirements Needed for Photosynthesis 1) Sunlight (ROY G BIV) Sunlight (photons): electromagnetic energy from the sun

26 Requirements Continued 2) Pigments (absorb or reflect sunlight) a. Chlorophyll is the major pigment used in photosynthesis. What do accessory pigments do? (1) Chlorophyll is a molecule that absorbs light energy. (2) Two types of Chlorophyll Chlorophyll a (main pigment) Chlorophyll b (accessory pigment) (2) In plants, chlorophyll is found in organelles called chloroplasts. They capture the radiant energy that chlorophyll a can not capture

27 Requirements Needed for Photosynthesis 3. Energy-Storing Compounds a. NADP NADPH b. ATP 4. Water 5. Carbon dioxide 6. Plants/Autotroph

28 C. Photosynthesis 3. Location for Photosynthesis 1) Chloroplast of Plants a. Grana (thylakoids) (1) Look like stacks of pennies b. Stroma (1) Liquid outside grana (2) Similar to cytoplasm grana (thylakoids) chloroplast stroma

29 Quick review 1. What is the energy transformation in photosynthesis:?? 2. Carbon dioxide + water glucose + oxygen * What process is this chemical reaction demonstrating? * What is missing from the equation? 3.

30 Quick review 1. (anabolic or catabolic) photosynthesis 2. What parts are located in the chloroplast? liquid (cytoplasm) stacks pieces of the stacks 3. Where exactly is chlorophyll located? What is its role? 4. Name the 2 energy-storing compounds used in photosynthesis. 5. Why would a plant s roots lack chloroplast? * what is the role/job of chloroplast? * why would the root lack this?

31 C. Photosynthesis 4. Two Phases of Photosynthesis 1) The Light Reactions (Light Dependent Reactions) 2) The Calvin Cycle (Light Independent Reactions)

32 D. The Light Reactions/Light Dependent Reactions capture energy from sunlight 1. Purpose: 1) Use the energy from the sunlight in order to make the energy-storing compounds. 2. Location: 1) Thylakoids -Grana chloroplast grana (thylakoids) stroma

33 D. Light Reactions 3. Overall Steps 1) Sunlight is captured by chlorophyll a located in the thylakoids.. 2) The energy from sunlight is captured by chlorophyll a and is transferred along the thylakoid membrane. 3) The energy carried along the thylakoid membrane is transferred to the energy-storing molecules of NADP and ATP. 4) Water molecules are broken down. 5) Oxygen from the water molecule is released to the air. H 2 O H + + O 2 (released to the air)

34 Light Reactions Quick Review 1. Sunlight is captured by chlorophyll a 2. This radiant energy moves along the thylakoid membrane and ultimately makes ATP and NADP (NADPH). Energy Storing Compounds 3. Water is broken Hydrogen is captured by NADP and makes NADPH Oxygen leaves to the atmosphere as a byproduct

35 E. The Calvin Cycle (light-independent reactions) 1. Purpose 1) Make Sugar (C 6 H )

36 E. Calvin Cycle 2. Location 1) Takes place in the stroma 3. When does it occur? 1) Immediately after the Light reactions.

37 E. Calvin Cycle Overall Steps 1) CO 2 is used to build larger molecules (carbohydrates, lipids and amino acids). Step 1: Carbon Fixation 1) CO2 joins with a 5-carbon compound called RuBP, making a 6-Carbon compound. (inorganic Carbon Dioxide is Fixed and turned into an organic compound)

38 E. Calvin Cycle Steps Continued Step 2: The 6-C compound breaks apart into two 3-Carbon compounds (this is called PGA) Step 3: PGA is converted into PGAL (with the help of ATP and NADPH) Step 4: PGAL can be used to make: glucose, RuBP, amino acids and other organic compounds.

39 E. Quick Review of the Calvin Cycle CO2 + RuBP 6-Carbon Compound 6-C compound breaks into two 3-C compounds (PGA) PGA PGAL PGAL glucose (amino acids, RuBP and other organic compounds)

40 Let s Review: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 H 2 O was used to form the product of.. CO 2 was used to form the product of 1 chloroplast granum (stack of thylakoids) 6H 2 O 2 6O 2 6CO 2 thylakoid energy stroma (fluid outside the thylakoids) 1 six-carbon sugar 3 4 C 6 H 12 O 6

41 F. Factors That Affect The Rate of Photosynthesis Temperature a. As temperature increases, the rate increases to a maximum and then will decrease with a further rise in temperature? b. Why? Enzymes that catalyze the reaction become ineffective at a certain temperature. Also, the stomata will close which will limit the amount of carbon dioxide that will enter the cell.

42 F. Factors That Affect The Rate of Photosynthesis Light Intensity a. Rate increase as light intensity increases. b. At some point, all available electrons are excited and the maximum rate of photosynthesis will be reached. The rate will then remain steady regardless of the amount of light.

43 F. Factors That Affect The Rate of Photosynthesis Carbon dioxide levels a. Same as light levels.

44 G. Alternative Pathways to Photosynthesis 1. The C 4 Pathway a. Plants that evolved in climates that have hot days and cooler nights will carry out this pathway. (corn, sugar cane, crabgrass) b. Stomata is partially closed during the hottest part of the day (water conservation) c. Contain an enzyme that will allow for carbon dioxide fixation even when carbon dioxide levels are low. The compounds will be sent to another cell will the Calvin cycle can resume

45 G. Alternatives Pathways to Photosynthesis 2. The CAM pathway a. Plants that have evolved in hot, dry climates. (cactus, pineapples) b. Open stomata at night and carbon dioxide fixation takes place at night and the Calvin cycle will pick up in the morning. This minimizes water loss.