Flashcards in Ch. 8 Photosynthesis Deck (53)
biochemical process for building carbohydrates from sunlight and carbon dioxide; carbohydrates are then used to make ATP
what has more energy stored in bonds? CO2 or Carbs?
photosynthesis requires an input of energy. where does this energy come from?
when a molecule acquires electrons and gains energy
when a molecule loses electrons and releases energy
what happens to CO2 during photosynthesis?
CO2 molecules are reduced to form higher-energy carbohydrate molecules
where do the electrons that reduce CO2 come from? what is the ultimate electron donor?
they other electrons come from the oxidation of other molecules
ultimate electron donor is water!
what does the oxidation of water ultimately produce as by products?
electrons, protons, O2
what is the formula for photosynthesis?
CO2 + H2O = C6 H12 06 + O2
what is the photosynthetic electron transport chain? (PETC)
series of redox reactions in photosynthesis
1. absorption of light by photosystems
2. movement of electrons to drive the production of ATP and NADPH
3. ATP and NADPH are energy sources for the calvin cycle which produces carbohydrates using CO2
absorb light and set the PETC in motion
how much carbon does photosynthesis remove from the atmosphere per year?
100 billion metric tons
what organisms mainly carry out marine photosynthesis?
phytoplankton (single celled eukaryotes)
cyanobacteria (photosynthetic bacteria)
marine surface layer about 100m deep where photosynthesis occurs
prior to photosynthetic evolution, what were the limitations of simple photosynthetic organisms?
-they only had one photosystem, this could not capture enough electrons to oxidize water and reduce electrons to CO2
-they didn't produce O2 as a by product because they didn't use water
-were limited to environments where HS2 electron donors were present
who were the first organisms who were able to pull electrons from water?
-they incorporated 2 photosystems into a single PETC
where did all of the oxygen in the earth's atmosphere come from?
it came from photosynthesis by organisms containing two photosystems!
horizontal gene transfer
the transfer of genetic material between organisms that are NOT parents and offspring
how did bacteria obtain photosynthetic capabilities?
horizontal gene transfer
endosymbiosis of cyanobacteria ---> chloroplasts
third highly folded membrane which fills much of the center of the chloroplast
-location of the PETC
groups of flattened thylakoid membrane sacs
fluid filled interior compartment of thylakoid membrane
surrounding region of thylakoid membrane
where is the outer membrane of the chloroplast double membrane thought to have come from?
from the plasma membrane of the eukaryotic cell which surrounded the ancestral cyanobacterium as it was being engulfed
where is the inner membrane of the chloroplast double membrane thought to have come from?
form the plasma membrane of the ancestral free-living cyanobacterium
what does the thylakoid membrane correspond to in ancestral cyanobacterium? what does the stroma correspond to?
thylakoid membrane - internal photosynthetic membrane found in cyanobacteria
stroma - cytoplasm of the ancestral cyanobacterium
how many chloroplasts can one photosynthetic cell have?
100! (it also has mitochondria)
how many chemical reactions does the Calvin Cycle consist of? what are the 3 main parts?
15 total reactions
define carboxylation as it pertains to the Calvin cycle
CO2 absorbed from the air is added to 5 carbon sugar called RuBP
-this is catalyzed by the enzyme rubisco (acts as a carboxylase)