PHOTOSYNTHESIS

Photosynthesis carbon dioxide + water + energy glucose + oxygen photosynthesis- the process of using light energy from the sun to convert carbon dioxide and water into glucose or carbohydrates chemical formula: 6 CO2 + 6 H2O + energy  C6H12O6 + 6 O2 carbon dioxide + water + energy glucose + oxygen

Autotrophs performed by autotrophs or plants autotrophs- organisms that are capable of making their own food, glucose

Conditions Necessary For Photosynthesis sunlight- only the red and blue wavelengths of white light are involved in photosynthesis chlorophyll- a green pigment in plants that traps energy from the sun water- supplies the hydrogen atoms (ions) needed to make glucose carbon dioxide- supplies the carbon and oxygen atoms needed to make glucose

Photosynthesis All organisms use energy to carry out functions for life. All energy is obtained directly or indirectly from the sun. Some organisms can trap energy from light and store it within organic compounds called photosynthesis.

Importance of Photosynthesis provides food for plants and animals in the form of carbohydrates or sugar or glucose uses oxygen as a waste product which is released into the atmosphere changes the energy from the sun into a usable form for living organisms provides the structural components in the cell walls of plants which is cellulose

Chloroplasts photosynthesis takes place inside the chloroplast chloroplast has a double membrane with the inner membrane having many folds the folds of the inner membrane fuse to together to form thylakoids thylakoids- disk-shaped structures that contain chlorophyll; resemble coins

Chloroplast- continued neatly stacked thylakoids are called grana a gel-like solution surrounds the grana and completely fills the inner membrane called the stroma Chlorophyll a absorbs more red light and less blue light than Chlorophyll b only Chlorophyll a is directly involved in the light reactions of photosynthesis

Process of Photosynthesis Stage 1- Light Dependent Reactions Stage 2 – Light Energy Converted to Chemical Energy Stage 3 – Calvin Cycle

Stage 1: Light Dependent Reaction takes place inside the thylakoids energy is captured by chlorophyll from sun light water is split into hydrogen ions, oxygen ions, and electrons hydrogen ions are used to make glucose energy released from electrons are used to make ATP molecules which are high energy molecules oxygen is released from the chloroplast into the atmosphere energy is also stored in NADP+ which is an electron acceptor; once joined with an electron it becomes NADPH

Stage 2: Conversion of Energy light energy is converted to chemical energy energy is stored in the form of ATP and NADPH molecules ATP- high energy molecules NADPH- electron acceptors

Stage 3: Calvin Cycle occurs inside the stroma carbon dioxide and hydrogen combine to form glucose energy stored in ATP and NADPH are used to form glucose

Stage 1: Light Dependent Reaction requires sunlight and takes place in the thylakoids the energy absorbed by the electrons of Chlorophyll a (photosynthesis II or I) causes these electrons to enter a higher energy level or “energized” energized electrons leave Chlorophyll a (photosystem II) which makes Chlorophyll a oxidized and must undergo reduction to add back electrons

Stage 1: Light Dependent Reaction energized electrons combine with molecules called the primary electron acceptors primary electron acceptors- capture these loose electrons primary electron acceptors guide the electrons to the electron transport chain electron transport chain- transfers the high energy electrons from one molecule to the next in the series this energy is used to make ATP molecules

Stage 1: Light Dependent Reaction an enzyme inside the thylakoid splits a water molecule into hydrogen ions (H+ or protons), oxygen gas, and electrons electrons released when the water molecule splits in the thylakoid replaces the electrons lost from the Chlorophyll a in photosystem II combine with Chlorophyll a in photosystem I electrons in both photosystems must be replenished in order for photosynthesis to occur oxygen is released into the atmosphere

Stage 2: Energy Conversion First Path ATP molecules are made by joining a phosphate group to ADP or two phosphate groups to AMP ATP or adenosine triphosphate- a high energy compound that supplies energy for all chemical reactions within a living organism ADP or adenosine diphosphate- results when ATP loses a phosphate group to release energy AMP or adenosine monophosphate- results when ADP loses a phosphate group to provide energy

Stage 2: Energy Conversion electrons + ADP + 1 phosphate group = ATP electrons + AMP + 2 phosphate groups = ATP

Stage 2: Energy Conversion Second Path energized electros in Chlorophyll a (photosystem I) are accepted by the primary electron acceptors again these electron acceptors direct the energized electrons to a different electron chain transport electrons combine with a hydrogen ion and NADP+ to form NADPH

Stage 2: Energy Conversion Second Path NADP+ - an organic compound that accepts electrons NADPH- an energy storing compound that will be used in the Calvin Cycle hydrogen is bonded to NADPH to be used in making glucose in Calvin Cycle

Stage 3: Calvin Cycle (Dark Reaction) energy is supplied by ATP and NADPH which were made in the light reaction simple inorganic compounds of carbon dioxide are used to make a complex organic compound called glucose or carbohydrates carbon fixation- carbon atoms from carbon dioxide are bonded into organic compounds takes place in the stroma of the chloroplasts carbon dioxide combines with a five-carbon compound called RuBP(ribulose bisphosphate) to form a six-carbon compound

Stage 3: Calvin Cycle carbon dioxide joins with RuBP to form a six-carbon compound that splits into 2 three-carbon compounds called PGA (phosphoglyceric acid or 3-phosphoglycerate) PGA is converted into another three-carbon compound called PGAL (phosphoglyceraldehyde) PGA + phosphate group + hydrogen = PGAL (ATP) (NADPH)

Stage 3: Calvin Cycle products of the Calvin Cycle are PGAL, phosphate group, ADP, and NADP+ most PGAL is changed back into RuBP some PGAL is converted into amino acids, lipids, and carbohydrates

Rate of Photosynthesis light intensity- increase light intensity, increases photosynthesis for a limited time, then levels off carbon dioxide- increase carbon dioxide, increases photosynthesis for a limited time, then levels off temperature- increase temperature, increases photosynthesis chlorophyll- increase the amount of chlorophyll, increase photosynthesis

END Note Quiz

Note Quiz What are the products of the Calvin Cycle? What are the two wavelengths of light that are used in photosynthesis? What is the role of chlorophyll in photosynthesis? What is the compound that carbon dioxide will combine in the Calvin Cycle? What are the products of the Light Dependent Reaction?

6. What does water supply in the process of photosynthesis? 7. What are the energy sources used in the Calvin Cycle or Dark Reaction? 8. What is PGAL? 9. How is PGA formed? 10. What does carbon dioxide contribute to photosynthesis?