photosynthesis and respiration 2
Terms
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- photosynthesis
- chloroplasts capture ligh energy from the sun and convert it to chemical energy stored in sugar and other organic molecules
- autotrophs
- "self-feeders" sustain themselves without eating anything derived from other organisms
- heterotrophs
- live on compounds produced by other organisms
- chloroplast
- organelle. site of photosynthesis
- chlorophyll
- the pigment located in chloroplasts. light energy absorbed by chlorophyll drives synthesis of organic molecules in the chloroplast.
- mesophyll
- the tissue in the interior of the leaf where chloroplasts are found. Each cell ontains about 30-40 chloroplasts
- stomata
- microscopic pores where carbon dioxide enters and oxygen exits leaves
- stroma
- the dense fluid within the chloroplast
- thylakoids
- elaborate system of interconnected membranous sacs called thylakoids that segregates the stroma from the thylakoid space.
- thylakoid space
- interior of thylakoids
- grana
- stacked columns of thylakoid sacs
- light reactions
- the photo part of photosynthesis. convert solar energy to chemical energy.
- photophosphorylation
- the addition of a phosphate group to ADP by chemiosmosis
- carbon fixation
- the initial incorporation of carbon into organic compounds
- wavelength
- the distance between the crests of electromagnetic waves
- electromagnetic spectrum
- the entire range of radiation
- visible light
- the range of radiation from 400-700 that is detected as various colors by the human eye
- spectrophotometer
- directs beams of light of different wavelengths through a solution of the pigment and measures the fraction of the light transmitted at each wavelenth
- why is visible light important in biological processes?
- longer wavelengths don't have enough energy, they merely vibrate molecules; and shorter wavelengths have too much energy, they destroy molecules. Visible light excites electrons to higher energy states, and cells can harness that energy to do work.
- our eyes are most sensitive to what color?
- green
- plants absorb...and don't use...
- absorb blues and reds. don't use greens
- overall reaction of photosynthesis
- 6 H2O + 6 CO2 --> C6H12O6 + 6O2
- water is carried to the leaves via tubular cells called
- xylem
- The oxygen released by photosynthesis comes from?
- H2O. The oxygen in CO2 goes to glucose and to newly regenerated H2O.
- What happens in the light reactions...?
-
Light energy is captured.
High energy nucleotides ATP and NADPH are formed.
Water is split.
-Electrons go to NADPH
-NADP is reduced to NADPH (a higher energy form)
-Oxygen is released as a byproduct. - What happens in the Calvin Cycle...? (and aka what?)
-
aka carbon fixation reactions
-ATP and NADPH give up their energy
-Energy is used to build glucose from CO2 - Photosystems? where are they?
- groups of Chlorphyll and accessory pigment molecules (chl.a and chl.b, carotenes) on the thylakoid membranes. clustered around one special molecule of chlorophyll a in the reaction center
- PS II
- reaction center contains a P680 - a chemical form of chlorophyll a that has a maximum light absorbance at 680 nm.
- PS I
- reaction center contains P700 - a chemical form of chlorophyll with maximum light absorbance of 700 nm.
-
Non-cyclic electron flow.
Generates what? Involves what? - most important pathway in light reactions. Generates both ATP and NADPH. Involves PSII and PSI.
- Cyclic electron flow. Occurs when ? Involves what? What is formed?
- Occurs at the same time as the non-cyclic pathway; involves only PSI. Only ATP formed.
- G3P
- Direct product of the Calvin Cycle. triose sugar. two molecules spontaneously unite to form Glucose.