Ch.10 Photosynthesis Flashcards
photosynthesis
process that converts solar energy into chemical energy and occurs in plants, algae, certain other protists, and some prokaryotes
autotrophs
produce organic molecules from CO2 and other inorganic molecules
photoautotrophs
(almost all plants)
use the energy of sunlight to make organic molecules from H2O and CO2
heterotrophs
consume organic material from other organisms
where does photosynthesis occur
mostly in the leaves
stomata
microscopic pores where CO2 enters and O2 exits the leaf
mesophyll
interior tissue of the cell
thylakoids
connected sacs in the chloroplast
grana
stacks of thylakoids
where is chlorophyll found
in thylakoid membrane
stroma
contained in chloroplasts, dense fluid
what does chlorophyll do?
absorbs light energy in order to drive the synthesis of organic molecules in the chloroplast
photosynthesis is a redox reaction, what is oxidized/reduced?
H2O is oxidized
CO2 is reduced
two parts of photosynthesis?
- light reactions (“photo”)
- Calvin Cycle (“synthesis”)
what happens during light reaction in the thylakoids?
- H2O splits
- O2 released
- NADP+ — > NADPH
- ADP —-> ATP via phosphorylation
wavelength
distance between crests of waves
electromagnetic spectrum
entire range of electromagnetic energy or radiation
visible light
wavelengths that produce colors we can see
photons
discrete particles that makeup light
spectrophotometer
measure a pigment’s ability to absorb various wavelengths
absorption spectrum
graph plotting a pigment’s light absorption versus wavelength
chlorophyll a
suggests violet-blue and red light work best for photsynthesis
carotenoids
absorb excessive light that would damage chlorophyll
what happens when a pigment absorbs light
it goes from a stable ground state to an excited state
fluorescence
afterglow produced when electrons fall back to ground state and some of their photons are given off
photosystem
reaction-center complex surrounded by light-harvesting molecules
reaction-center complex
protein complex
light-harvesting complexes
pigment molecules bound to proteins that funnel the energy of photons to the reaction center
photosystem II
functions first and is best at absorbing wavelength of 680nm
photosystem I
best at absorbing wavelength of 700nm
P680
reaction-center chlorophyll of a of PS II
P700
reaction-center chlorophyll a of PS I
chemiosmosis
- mitochondria generate ATP from food
- chloroplasts transform light energy into chemical energy of ATP
chemiosmosis in mitohondria
protons are pumped to the intermembrane space and drive ATP synthesis as they diffuse back into the mitochondrial matrix
chemiosmosis in chloroplasts
protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma
Calvin Cycle does what?
uses ATP and NADPH to convert CO2 to sugar
how does the Calvin Cycle work?
carbon enters the cycle as CO2 and leaves as sugar (glyceraldehyde-3-phosphate, G3P)
how many cycles for 1 G3P?
3
phases of the Calvin Cycle?
- carbon fixation
- reduction
- regeneration of the CO2 acceptor (RuBP)
what catalyzes carbon fixation?
rubisco
what happens to plants on hot days?
stomata closes to conserve H2O causing O2 buildup, cutoff CO2 access and reducing photosynthesis
photorespiration
wasteful process in plants which is favored by the condition brought about by a hot summer day
cyclic electron flow
uses only photosystem I and produces ATP satisfying higher demand in Calvin Cycle, no NADPH
C4 plants
minimize cost of photorespiration by incorporating CO2 into four-carbon compounds in mesophyll cells
crassulacean acid metabolism (CAM)
used by some plants, this is a form of carbon fixation in which the stomate opens at night taking in CO2, and closes during the day to release CO2 from organic acids and use it in the Calvin Cycle
