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Photosynthesis. Energy & Life. Energy – the ability to do work; all living things depend on energy Sun = main source Autotrophs – producers; have ability to make their own food Ex.) Plants; photosynthetic bacteria; algae
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Energy & Life • Energy – the ability to do work; all living things depend on energy • Sun = main source • Autotrophs – producers; have ability to make their own food Ex.) Plants; photosynthetic bacteria; algae • Heterotrophs – consumers; obtain energy needed from consumption of food Ex.) Herbivores, Carnivores, Omnivores
Chemical Energy & ATP • Energy = stored in chemical compounds • ATP – adenosine triphosphate; composed of ribose (sugar); a base (adenine) & 3 Phosphate groups; used by cells for an energy source How It Works (Releasing Energy) • Enzymes cause ATP to lose a P-group • Exothermic rxn – large amounts of energy is released for use by the cell; high energy bonds are broken • ADP (adenosine diphosphate) is resulting product • A 2nd p-group can be extracted to provide the cell with even more energy = AMP (adenosine monophosphate)
Storing Energy • When an organism is at rest, phosphate groups are reattached to the molecule using energy obtained from food or sunlight • ATP = chemical battery = has ability to store or release energy depending on the needs of the cell
ATP Uses • Powers the Na+/K+ pump = maintains a balance of ions on either side of the plasma membrane • Provides energy for locomotion • Protein synthesis • Light production – glow from firefly • Cells have a small supply on hand = short-term energy source for the cell
Assignment: Pg. 203 (1-5) & Focus on the Big Idea Section 8.1 ws packet
Investigating Photsynthesis • Photosynthesis- uses the energy of sunlight to convert water and CO2 into high energy sugars (glucose) & oxygen • Plants also require chlorophyll to absorb light energy from the sun • Chlorophyll –pigment contained in chloroplast; energy absorbed into this molecule raises the energy level of the electrons contained within it; high energy electrons enable photosynthesis
Thylakoids – arranged in stacks known as grana; contain photosystems that absorb light energy • Stroma – fluid that fills the inside of the chloroplast; Calvin Cycle takes place here
Overview of Photosythesis STAGE 1 – called the light dependent reactions Energy is captured from sunlight Water is Split into Hydrogen Ions, Electrons, and Oxygen (O2). Oxygen diffuses out of the chloroplasts (Byproduct) STAGE 2 – light energy is converted into chemical energy, which is temporarily stored in ATP and NADPH (carrier molecule) STAGE 3 – Calvin Cycle; the chemical energy stored in ATP and NADPH powers the formation of organic compounds (Sugars), using CO2
Light-dependent reaction - chlorophyll converts sunlight energy into chemical energy (ATP and NADPH) Comparison to solar cells that convert solar energy into electricity to do work • Light-independent reaction – Calvin Cycle - uses the energy stored in ATP and NADPH during the Light Reactions to produce organic compounds (carbs)
Bonus: Ch 8 Photosynthesis Quiz • NADPH: Nicotinamide adenine dinucleotide phosphate 10 Points