Topic 7 Flashcards
light dependent reactions
occur in the thylakoid disk
steps:
Capturing Energy from sunlight
Using the energy to make ATP and to reduce the compound NADP+, an electron carrier, to NADPH.
Detailed steps:
Primary photoevent – a photon of light is captured by a pigment, which will excite an electron within the pigment.
Charge separation – This excitation energy is transferred to the reaction center, which transfers an energetic electron to an acceptor molecule, initiating electron transport.
Electron Transport – The excited electrons are shuttled along a series of electron carriers molecules embedded within the photosynthetic membrane, generating a proton gradient.
Chemiosmosis – The protons that accumulates on one side of the membrane now flows back across the membrane through ATP synthase where chemiosmotic synthesis of ATP takes place, just as it does in aerobic respiration.
carbon fixation
(light-independent reactions)
Using the ATP and NADPH to power the synthesis of organic molecules from CO2 in the air
Stroma also contains enzymes that catalyze the reactions of carbon fixation – the Calvin cycle reactions
Carbon Fixation – RuBP + CO2 → PGA
The Calvin Cycle
occur in the stroma and is a light independent reaction (can be done at night)
Stroma also contains enzymes that catalyze the reactions of carbon fixation – the Calvin cycle reactions
Cells used ATP from light-dependent reactions (Cyclic and noncyclic photophosphorylation) to build carbohydrates, from CO2
Key step is the attachment of CO2 to RuBP to form PGA
Uses enzymes ribulose bisphosphate carboxylase/oxygenase or Rubisco.
3 main phases
Carbon Fixation – RuBP + CO2 → PGA
Reduction - PGA is reduced to G3P
Regeneration of RuBP –
PGA is sued to regenerate RuBP
3 turns incorporate enough carbon to produce a new G3P
6 turns incorporate enough carbon for 1 glucose.
light independent reactions
occur in the stroma ex. Calvin cycle
does not require light so it can be done at night
pigments
Thylakoid disk which contain chlorophyll, and other photosynthetic pigments for capturing light energy (light dependent reactions occur)
Photosynthetic pigments like chlorophyll, and Carotenoids are molecules that absorb light energy in the visible range.
two types chlorophylls and accesory pigments
chlorophyll (A&B)
Chlorophyll a – is the main pigment found in the chloroplast of plants and cyanobacteria and is the only pigment that can act directly to convert light energy to chemical energy. Absorb violet-blue and red light.
Chlorophyll b – acts as an accessory pigment, or secondary light-absorbing pigments, by complementing the spectrum that Chlorophyll a does not absorb.
carotenoids
an accessory pigment
another accessory pigment, that can absorb photons with a wide range of energies but assist in capturing energy not efficiently absorbed by chlorophylls.
Carotenoids also preform a protective role in a scavenging free radicals from redox-reactions occurring in chloroplasts.
phycobiliproteins
are another accessory pigment found in cyanobacteria and some algae, and are important in low-light ocean areas
photon
discrete bundles of energy, acting both as particles of light, but also as a wave. The energy content of a photon is inversely proportional to the wavelength of light.
photorespiration
oxidization of RuBP by the addition of O2 is preferred reaction when stomas are closed in hot conditions, and creates an environment of Low- CO2, and High- O2
C3
Produces a three-carbon compound via the Calvin cycle.
It’s a one-stage process that takes place inside of the chloroplast organelles
About 85% of the plant species on the planet are C3 plants, including rice, wheat, soybeans and all trees
C4
Produces an intermediate four-carbon compound that splits into a three-carbon compound for the Calvin cycle
The photosynthetic process occurs in the chloroplast of a thin-walled mesophyll cell.
The benefit of C4 photosynthesis is that it produces a higher concentration of carbon, making C4 organisms more adept at surviving in habitats with low light and water
CAM
CAM photosynthesis gathers sunlight during the day and fixes carbon dioxide molecules at night.
In this type of photosynthesis, organisms absorb sunlight energy during the day then use the energy to fix carbon dioxide molecules during the night
Understand and identify the process of photosynthesis, and why these reactions are important?
babes go look at the powerpoint because that is a lot of information
In plant cells the organelle responsible for photosynthesis is?
chloroplasts
The photosystem organized into a light-harvesting complex, that captures photons from sunlight before channeling them is called?
The antenna complex
The overall process of photosynthesis results in?
results in the reduction of CO2 and the oxidation of H2O
The ultimate source of energy that supports life on earth is from where?
photons from the sun
The ATP and NADPH from photosynthesis are used in?
Used in reactions of the Calvin cycle to produce glucose
The Calvin cycle uses what molecule to create organic compounds?
CO2
What is the main light-independent reaction in photosynthesis?
The Calvin Cycle
The products produced by light-dependent reactions of photosynthesis, of which of the following?
oxygen, ATP, NADPH
The overall function of the Calvin Cycle is?
making glucose
what is part of the photosystem that transfers the energized electron to the primary electron acceptor?
reaction center complex
List and define the organization of Chloroplast, including the location of Thylakoid disk, Chlrorphyll, Storma, and where exactly reactions occur.
Chloroplast Membranes: The chloroplast is surrounded by a double membrane, similar to the double membrane found within a mitochondrion.
Stroma: The stroma is the fluid-filled space that exists between the thylakoid and the chloroplast membranes. It contains enzymes that work with ATP and NADPH to “fix” carbon from carbon dioxide into molecules that can be used to build glucose. The light-independent reactions of photosynthesis, also known as the Calvin cycle, take place within the stroma.
Thylakoid Membrane: Within the chloroplast is a third membrane that forms stacked, disc-shaped structures called thylakoids. The thylakoid membrane is where the light-dependent reactions of photosynthesis occur.
Thylakoid Disk: Thylakoids are interconnected disc-like sacs that make up the chloroplast’s internal membrane system. They are found suspended in the stroma.
Chlorophyll: Chlorophyll, a green pigment responsible for capturing sunlight energy, is located within the thylakoid membrane. It plays a crucial role in initiating the process of photosynthesis
Compare and contrast the differences between Photosynthetic pigments: Chlorophyll A, B, and Carotenoids, in the aspects of the wavelength of light they absorb and reflect.
Chlorophyll A
It is a primary pigment in plants and algae.
It absorbs light most strongly in the blue-violet and red regions of the spectrum.
It reflects green light, which is why it appears green.
Chlorophyll B
It is an accessory pigment that complements Chlorophyll A.
It absorbs light most strongly in the blue and red-orange regions of the spectrum.
Like Chlorophyll A, it also reflects green light.
Carotenoids
They are accessory pigments that include xanthophylls and carotenes.
They absorb light most strongly in the blue-green and violet regions of the spectrum.
They reflect longer yellow, red, and orange wavelengths, which is why they appear as such colors
Define and identify the overall process of the Calvin Cycle (Carbon Fixation), with highlighting the overall process of this reaction.
Carbon Fixation: The enzyme RuBisCO incorporates carbon dioxide from the atmosphere into an organic molecule, 3-PGA.
Reduction Phase: The organic molecule 3-PGA is reduced using electrons supplied by NADPH. ATP and NADPH, which are produced in the light-dependent reactions of photosynthesis, are used to convert the 3-PGA molecules into molecules of a three-carbon sugar, glyceraldehyde-3-phosphate (G3P).
Regeneration Phase: Some G3P molecules go to make glucose, while others must be recycled to regenerate the RuBP acceptor. This requires ATP and involves a complex network of reactions
reaction center
consists of one or more chlorophyll a molecules in a matrix of proteins, that passes excited electrons out of the photosystem
