Chapter 10: photosynthesis Flashcards
How is light electromagnetic energy?
photons of light(“packets” of electromagentic energy) can provide certain things energy(like plants for photoysnthesis, and NEED for life!)
Wavelength relationships
Purples/blues have shorter wavelength and higher energy
Reds/oranges have longer wavelength and lower energy
Structure of chloroplasts
granum, thylakoid membrane and lumen, and stroma
What does the Granum provide during light dependent reactions?
stack of thylakoids
The importance of the granum lies in its role in the light-dependent reactions of photosynthesis; primary means by which energy is captured and stored in plants and other photosynthetic organisms.
During the light-dependent reactions, the thylakoid membranes of the granum absorb light energy and use it to generate a flow of electrons that are passed through a series of protein complexes, generating ATP and NADPH. The stacked arrangement of the thylakoid membranes in the granum provides a large surface area for the absorption of light, maximizing the efficiency of photosynthesis
How does granum regulate light?
In bright sunlight, the granum can become tightly stacked, reducing the amount of light absorbed and protecting the photosynthetic machinery from damage caused by excess light. In low light conditions, the granum may become less tightly stacked, allowing for more efficient light absorption and energy production.
Thylakoid membrane and lumen
membrane-bound structures found in chloroplasts, which are the organelles responsible for photosynthesis in plant cells. The thylakoids contain chlorophyll and other pigments that capture light energy from the sun, which is then used to drive the process of photosynthesis.
The purpose of thylakoids is to provide a large surface area for the light-dependent reactions of photosynthesis. These reactions occur in the thylakoid membranes, where chlorophyll and other pigments absorb light energy and convert it into chemical energy in the form of ATP and NADPH
Stroma
The stroma is a fluid-filled region that surrounds the thylakoid membranes inside chloroplasts, the organelles responsible for photosynthesis in plant cells.
The purpose of the stroma is to provide a space for the light-independent reactions of photosynthesis to occur, including the fixation of carbon dioxide into organic compounds.
The light-independent reactions of photosynthesis, also known as the Calvin cycle, take place in the stroma of chloroplasts
Structure of chlorophyll
includes head ring structure that absorbs light
tail anchors chlorophyll in thylakoid membrane
Why doe plants mostly look green
pigments absorb from blue/red ends of spectrum, reflect green light
Why doe plants mostly look green
pigments absorb from blue/red ends of spectrum, reflect green light
blue and red light efficiently excites electrons: * Blue photon jump is greater than red, since blue has higher light produced/oxygen absorbed than red(example: blue would reach energy of two while red compared to it would reach 1)
Apply laws of thermodynamics to excitation of electrons
Conversion of energy from photic to chemical(1st law)
1st law: energy from photon striking a molecule raises an electron level of a molecule, can possibly change chemistry of molecule
some wasted energy (fluorescence and/or heat)(2nd law)
oxygen waste product in photosynthesis
Chlorophyll A
CH_3; absorb in the blue and purple part of spectrum, not as much in yellows and greens, larger amount in orange and red
Chlorophyll B
CHO; absorbs mostly blue photons of light and some red photons
Both chlorophylls absorbing blue and red will reflect back as green to us
How is NADPH an electron acceptor?
It is the last molecule in the process of light being given to an excited chlorophyll molecule
it donates electrons to Calvin cycle to reduce CO2 to carbohydrates
Role of photosystems II and I
photosystems II: photon captures antenna complex, resonance energy transfer excited reaction center electron; water is oxidized to gather electrons needed to move on in process and pump hydrogen into lumen for proton gradient
photosystem I: re-excites electrons with photons
Step 1 of photosynthesis in light dependent stage
Photosystems are a network of chlorophyll and proteins which help capture energy(Note the 3 different fates of electrons/energy: resonance or Redox are preferred!)
Electron Is struck with photons of light and can become excited(note that not every time it is grabbed is successful)
When an electron is successfully captured, we use resonance energy transfer; Energy in electron is transferred to nearby pigment
Energy of electrons can attract other electrons depending on excitement; Excitement will carry this energy hopefully to a reactant center; amount needed uncertain but likely more than one photon of light to reach center
Step 2 of photosynthesis light dependent stage
Photosystem II drives the formation of proton gradient, which generates ATP
Make ATP and reduce NADP+: light dependent stage
Note the electrons may or may not actually be going somewhere, but the energy is definitely being moved one way or another; Transport electrons through electron transport chain
Will reach photosystem 1 and eventually become 2 NADPH
role of electron transport chain in photosynthesis
pumps hydrogen into thylakoid lumen(used in proton gradient)
Explain antenna complex and reaction centers
the antenna complex provides a resonance energy transfer of electrons from photons of light to the reaction centers; reaction centers will become excited from more electrons to have their energy for photosynthesis
Light Independent(Calvin Cycle reactions):
creates long chain of carbohydrates; takes carbon dioxide from air to form long chains of carbohydrates
