Outcome: Explain the process of photosynthesis. Warm-up: 1. Compare the two types of cells. Give examples for each. 2. Using double bubble map, differentiate plants and animal cells. 3. What organelles is needed for photosynthesis to take place?
Carbon Cycle
The Carbon Cycle Carbon is the primary element of living things. Plants fix carbon when they use sunlight and CO2 to make sugars. Animals eat the sugars in the plants, some animals eat the animals that eat the plants Animals use O2 and the sugars to exhale CO2 3
Overview: The Process That Feeds the Biosphere Photosynthesis Is the process that converts solar energy into chemical energy
Photosynthesis Complete the photosynthesis gizmo
Plants and other autotrophs Are the producers of the biosphere
Autotrophs Organisms that can make their own food. Photoautotrophs: Use sun energy to make organic compounds (glucose) from light. Chemoautotrophs: Use chemical energy to makes organic compounds from chemical energy contained in inorganic substances 7
Plants are photoautotrophs They use the energy of sunlight to make organic molecules from water and carbon dioxide Figure 10.1
Photosynthesis Occurs in plants, algae, certain other protists, and some prokaryotes These organisms use light energy to drive the synthesis of organic molecules from carbon dioxide and (in most cases) water. They feed not only themselves, but the entire living world. (a) On land, plants are the predominant producers of food. In aquatic environments, photosynthetic organisms include (b) multicellular algae, such as this kelp; (c) some unicellular protists, such as Euglena; (d) the prokaryotes called cyanobacteria; and (e) other photosynthetic prokaryotes, such as these purple sulfur bacteria, which produce sulfur (spherical globules) (c, d, e: LMs). (a) Plants (c) Unicellular protist 10 m (e) Pruple sulfur bacteria 1.5 m Figure 10.2 (b) Multicellular algae (d) Cyanobacteria 40 m
Transfer and Use of Matter and Energy EQUATION Photosynthesis REACTANTS
What happens to the products? Products
How do autotrophs make their own food? Photoautotrophs Most autotrophs use sunlight to make their own food. Chemoautotrophs Some have found another way, using chemical energy (stored in bonds) to make food. 12
Photosynthesis Takes place in the chloroplasts of plant cells. Pigment molecules (chlorophyll) absorb energy from the sun, and use that energy to power photosynthesis. 13
How do plants use sunlight to make food? Pigments present in the cell absorb light (energy) Plants have many pigments to help absorb the light energy. Notice that they do not absorb light at these colors this is why plants are green; they reflect back green light. In the fall, the green pigments die off, leaving only the carotenoids behind (which reflect back orange and red light)
Where does photosynthesis occur? Chloroplasts
Chloroplasts 16
What types of organisms use photosynthesis? Autotrophs
Chloroplasts: The Sites of Photosynthesis in Plants The leaves of plants Are the major sites of photosynthesis Leaf cross section Vein Mesophyll Stomata CO 2 O 2
Chloroplasts Are the organelles in which photosynthesis occurs Contain thylakoids and grana Mesophyll Chloroplast 5 µm Outer membrane Stroma Granum Thylakoid Thylakoid space Intermembrane space Inner membrane 1 µm
The Two Stages of Photosynthesis: A Preview Photosynthesis consists of two processes The light reactions The Calvin cycle
What is ATP? ATP: Basic energy source of all cells Adenosine ribose 3 phosphates
What is ADP? ADP: Uncharged ATP; contains SOME energy, but less than ATP. Like a rechargeable battery. Store Energy: in chemical bond by adding a phosphate Release Energy: from chemical bond by breaking off a phosphate
How do you recharge ADP? ATP is not good for storing large amounts of energy over long periods of time, thus it is more efficient to only keep a small amount on hand in the cell. Cells regenerate ATP from ADP and phosphate ions using the energy stored in food (sugars) 23
Light Reactions Energy from the sun is used to make ATP from ADP by splitting water (creates O2 and H+). This molecule is easily broken down to release energy. Looks like a nucleotide, but with extra phosphate groups Energy is stored in the phosphate bonds.
Photosynthesis Light Dependent Reactions Light Independent Reactions H 2 O Light ATP CO 2 NADPH O 2 NADP ADP Calvin Cycle Organic Compounds (sugars)
Light Dependent Reactions 1. Electrons in chlorophyll are energized by light. 2. Electrons travel along a protein chain; energy used to make ATP and NADPH. 2H + + 2NADP + 4e - 2NADPH ADP + P ATP 3. Water is spilt by an enzyme, supplies materials for step 2, O 2 given off as by-product. 2H 2 O 4H + +O 2 + 4e-
Light dependent reaction The light reactions Occur in the grana Split water, release oxygen, produce ATP, and form NADPH The light reactions convert solar energy to the chemical energy of ATP and NADPH
Light Independent Reactions 1. ATP & NADPH (energy rich, but unstable) enter the Calvin cycle, along with CO 2. 2. Energy of ATP & NADPH powers enzymes, converting CO 2 into stable, high energy sugars. 3. ATP & NADPH are used up; become ADP & NADP, which are reenergized during the light reactions.
Dark Reactions ATP produced during the Light Reactions is used in the Dark Reactions to fix carbon into sugar. CO2 acts as the carbon source, ATP is broken down into ADP.
The Calvin cycle Occurs in the stroma Forms sugar from carbon dioxide, using ATP for energy and NADPH for reducing power
An overview of photosynthesis H 2 O CO 2 Light NADP LIGHT REACTIONS ADP + P CALVIN CYCLE ATP NADPH Figure 10.5 Chloroplast O 2 [CH 2 O] (sugar)
How do Plants do It? The entire process of photosynthesis process of making sugars from CO2 and sunlight is aided by enzymes. These enzymes are the most important enzymes on the planet they make life possible.
Factors that Affect Photosynthesis Light rate of photosynthesis increases until all the pigments are being used. CO2 the Calvin cycle only takes in so much CO2 at once. Once all the enzymes are occupied, the reaction is going maximum speed. Temperature unfavorable temperatures may inactivate certain enzymes. 33
Photosynthesis Summary