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Chapter 11- Energy Metabolism: Photosynthesis - Coggle Diagram
Chapter 11- Energy Metabolism: Photosynthesis
Energy and reducing power
Energy Carriers
Gaunosine triphosphate- contains chemical energy stored in its high-energy phosphate bonds. It releases energy when broken down
Three Methods in which adenosine diphosphate (ADP) can be phosphorylated to ATP
Photophosphorylation- Method 1/3. Involves light energy in photosynthesis.
Substrate-level Phosphorylation- Method 2/3. Compounds with high-energy phosphate groups which force their phosphate onto ADP, making ATP
Oxidative Phosphorylation- Method 3/3. In the last stages of respiration, ADP is phosphorylated to ATP.
Reducing Power
Terms and definitions
Oxidized- an atom does not carry as many electrons as it could
Oxidation State- Figurative- electrons spend more time near the oxygen than they do near the carbon, sulfur, or nitrogen, but they aren't torn away completely. These bonds are covalent.
Reduced- Electrons added to an atom
Redox Potential- Tendency to accept or donate electrons
Earth's atmosphere about 21% oxygen causing many compounds to be found in their oxidized forms
Electrons can only be transferred between atoms or molecules
Every oxidation occurs simultaneously with a reduction
Reducing Power is important to plants since they take in carbon dioxide and water.
Other Electron Carriers
Cytochromes- small intrinsic membrane proteins containing a cofactor, heme, which holds an iron atom. Integral part of chloroplast's thylakoid membranes and cannot be removed without destroying the membrane.
Plastoquinones- transports electrons short distances within membrane. after picking up 2 electrons, they bind 2 protons. Long hydrocarbon tail causes them to be hydrophobic. Dissolve easily into lipid component of chloroplast membranes.
Plastocyanin- Small protein, carries electrons on a metal atom. Loosely associated with chloroplast membranes. Can move short distances.
Photosynthesis
The LIGHT DEPENDENT REACTIONS (Thylakoid Reactions)- Water and light don't act on carbon dioxide directly, they create the intermediates ATP and NADPH by this process
Electromagnetic radiation spectrum- light is one small segment. It encompasses gamma rays, x-rays, UV light, infrared light, radio waves, and visible light.
Quanta- set of radiation particles (quantum, singular) also called photons, or a set of waves.
Radiation differs in their wave lengths and the amount of energy each individual quantum contains.
When quanta is absorbed by the pigment, and electron is ACTIVATED- raised to a higher energy level.
We say that the electron and molecule go from the ground state to an excited state.
The Stroma Reactions (formerly known as dark reactions)- ATP and NADPH interact with carbon dioxide and actually produce carbohydrates
It is important for plants to be able to obtain 'cheap' raw materials without spending a lot of energy.
Water and carbon dioxide are excellent because they diffuse into the plants from soil, air, or water.
Water and carbon dioxide are very stable and are non-toxic so they can be absorbed in large quantities.
Electron source- Water Energy source- Light
What humans can see/feel. We feel infrared as heat. UV causes skin to tan or burn. Most can see red (760nm) through orange, yellow, green, blue, indigo, to violet (390nm.)
LIGHT
Pigment- a substance will absorb all wave lengths except for one. That substance then becomes that distinctive color.
Accessory pigments- molecules that strongly absorb wavelengths not absorbed by chlorophyll a.
Resonance- chlorophylls act like 1 molecule, and the energy absorbed by one can be rapidly transferred to another in a different part of the complex.
300 chlorophylls, carotenoids, and their proteins are called an antenna complex.
When light strikes any pigment of an antenna complex, the energy is. transferred to a REACTION CENTER-a structure that contains a pair of special molecules of chlorophyll a.
Photosynthetic Unit- a granule that all pigments and carriers that work together are packed into
light can be important for flowers, fruits, or the skins of animals because it can help organisms attract mates, pollinators or frugivores or in hiding from predators.
Chorophyll a- absorbs only some red and blue light letting most of the rest pass through, especially high-energy radiation.
Chlorophyll doesn't use high-energy quanta because they have too much energy.
Photosystem I- photosynthetic unit with little chlorophyll b
Photosystem II- those in which chlorophyll b is present at levels almost equal to a.
Plants only capture about 5% of the energy available in the electromagnetic radiation that strikes them.
Fluorescence- release of light by a pigment
Absorption spectrum- a graph that shows which wave-lengths are most strongly absorbed.
Action spectrum- shows which wavelengths are most effective at powering a photochemical process.
Photochemical process- to initiate, light must first be absorbed; therefore the action spectrum must match the absorption spectrum of the pigments responsible.
Synthesis of ATP
Chemiosmotic Phosphorylation- process to make ATP. Indirect
Environmental and Internal Factors
Light
Quality of sunlight- refers to the colors or wavelengths it contains.
Quantity of light- refers to light intensity or brightness
Light compensation point- light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration.
Leaf Structure
Leaf structure depends on the plant's habitat. The structure helps retain water
C4 metabolism is a mechanism by which carbon dioxide is absorbed, transported through, and concentrated in a leaf, whereas oxygen is kept away from RuBP carboxylase.
Water
Affects photosynthesis
is conserved by structural modifications as well as metabolic adaptations. 2 of the most important are C4 metabolism and Crassulacean acid metabolism (CAM)
C4 metabolism- an important factor for plants is water loss. Water loss is preferably low.
RuBP carboxylase occasionally binds to oxygen instead of carbon dioxide, acting as an oxygenase and producing one molecule of 3-phosphoglycerate and 1 of phosphogylcolate.
C4 Metabolism
Much of the phosphoglycolate is broken down into2 molecules of carbon dioxide.
The breakdown is photorespiration, an energy wasting process
mesophyll cell contains the enzyme PEP carboxylase, which has a very high affinity for carbon dioxide.
Crassulacean
Crassulacean acid metabolism (CAM)- second metabolic adaptation that improves conservation of water while permitting photosynthesis.
first discovered in those members of the family Crassulaceae that have succulent leaves.
Oxygen and plants
oxygenic photosynthesis- oxygen is liberated as a waste product, as in plants
anoxygenic photosynthesis-is the phototrophic process where light energy is captured and converted to ATP, without the production of oxygen; water is, therefore, not used as an electron donor.
Crassulacean acid metabolism is a carbon uptake system utilized by many succulent plants; these plants fix carbon dioxide during the night when evapotranspiration is relatively low, storing it as organic acids.
Concepts
Living org. are highly ordered and structured systems.
Sunlight
Maintains and increases the orderliness of life
Indirectly by way of respiration of those organic compounds either by the organism itself or by another organism that eats it.
Directly by process of photosynthesis- produces complex organic compounds
Photoautotrophs
Organisms that gather energy directly from light and use it to assimilate small inorganic materials into their own tissues. Ex: green algae
Heterotrophs
Organisms that take in organic molecules and respire them, obtaining the energy available in them. Ex: humans
Photosynthesis, Global Warming, and Global Climate Change
Oxygen is produced solely by oxygenic photosynthesis. It originated 2.8 million years ago.
For millions of years the newly produced oxygen reacted with iron. After all iron had been oxidized, free oxygen accumulated in the atmosphere and keeps increasing.
Photosynthesis pulled carbon dioxide out of the atmosphere converting it to 3-phosphogyleraldehyde then all the other organic compounds that exist.
Every organic molecule started out as carbon dioxide snared by RuBP carboxylase.
Coccoliths are microscopic algae that builds shells of calcium carbonate, as do mollusks. When they pass the carbon in their shells slowly decomposes and releases that carbon.
Fire changed humans in that we now oxidize food in our mitochondria, wood coal, oil, and gas. Which puts carbon dioxide back into the atmosphere.
Greenhouse effect- Energy gets trapped in the atmosphere and warms our world.
Global Warming- concentration of carbon is rising and so does the temperature.
Global warming is also causing rapid melting of snow and glaciers in mountains and of ice caps in the Arctic and Antarctic.
Global climate change- Not all areas are affected the same. Wind patterns are being changed such that certain areas are becoming warmer, others cooler, some wetter, and others drier.
Farming areas are being abandoned, cities abandoned. With this other areas are becoming more suitable for farming as well.
Ozone-a colorless unstable toxic gas with a pungent odor and powerful oxidizing properties, formed from oxygen by electrical discharges or ultraviolet light. It differs from normal oxygen (O2) in having three atoms in its molecule (O3).
Stroma Reactions (Calvin/Benson Cycle; C3 cycle)- conversion of carbon dioxide to carbohydrate
Step 1: an acceptor molecule reacts with a molecule of carbon dioxide. Only carboxylation
Anabolic Metabolism
Storage compounds: Short-term, ATP and NADPH within cell short life. Intermediate-term, glucose and sucrose can move cell to cell and can last for weeks/months. Long-term, starch, can last for years
Synthesis of polysaccharides
Gluconeogenesis- anabolic synthesis of glucose