Photosynthesis Energy Life Energy the ability to do
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 § 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) 1. Enzymes cause ATP to lose a P-group 2. Exothermic rxn – large amounts of energy is released for use by the cell; high energy bonds are broken 3. ADP (adenosine diphosphate) is resulting product 4. A 2 nd 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 CO 2 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
Structure of a Chloroplast
§ 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 (O 2). 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 CO 2
§ 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
- Slides: 16