LIGHT DEPENDENT AND LIGHT INDEPENDENT REACTIONS
(photosynthesis is a 2-part process)
LIGHT DEPENDENT REACTIONS (pg. 157-160)
- occur in the ___________________ membrane
- sunlight (___________________) energy is converted into _____________________ energy of two different molecules: _____________ and _________________
- in the ____________________ membrane are highly organized assemblies called _______________________
- each ______________________ consists of 2 major parts:
- the ___________________________________ is composed of "___________________ pigments" (such as _____________________, _______________________, and ________________________) and single ______________________ molecule called the ________________ chlorophyll or ___________________ ______________________ chlorophyll
- the _______________ transports ____________________ (as in the mitochondrion).
- there are actually 2 types of photosystems: __________________________ and ____________________________. There are 1000's of copies of both.
STEPS IN THE LIGHT DEPENDENT REACTIONS
- As sunlight hits a leaf, some of the ______________ passes into it to the _____________ where it is absorbed by an ____________________ pigment in the ______________________________ complex of _____________________________ (PII). The energy from the light is passed from pigment to pigment until it reaches the single _________________________ molecule (called the ____________ chlorophyll, or chlorophyll P680).
- This energy boosts an ___________________ from __________________________ to a higher energy level. The electron is then passed to a primary ________________ and then to a molecule of PQ (____________________) which then passes the electron(s) to an ___________________ transport ____________________ or chain (ETS). This ETS is embedded in the ______________________ membrane.
- The ETS passes the energetic ______________________ from one carrier to the next in a series of ___________________ and ___________________ reactions. As the electrons travel, they release ____________________ which PQ (plastoquinone) uses to pump ____ ions from the ___________________ INTO the __________________ space. The ________ ions build up leading to an __________________________ gradient. They then flow _________________ the concentration gradient, through an ATPase complex, back into the ______________. As this happens, an enzyme converts _________ into _______. Because the source of energy to phosphorylate ____________ came from ____________________, this process is called "________________phosphorylation" and is a type of chemiosmosis like that in the mitochondrion. It takes 4 H+ to produce 1 ATP.
- The electrons continue on to Pc or ________________________ and then on to Photosystem I.
- At the same time as step 1-4 are happening, light is also striking __________________________ (PI). The energy is absorbed by _____________ pigments of the antenna complex and is passed from pigment to pigment until it reaches the ____________________ (____________ chlorophyll, P700). This chlorophyll then ejects an _______________ which is picked up by a primary ________________ which then gives the electron to Fd (______________________). Because PI loses _________________, they must be replaced. Replacement electrons comes down the _________ from PII. This is called "___________________ regeneration".
- Ferredoxin gives electrons to the enzyme NADP ________________ which also uses some H+ to reduce NADP+ to ___________.
- The electrons lost from the chlorophyll _______ of PII are replaced when a ______________ molecule in the _________________ space is split by a Z protein. This process is called "___________________". In addition to releasing electrons, this also releases _____________ and some ____ ions (which aid in ATP production).
H2O -------------> 1/2 ________________ + 2 ______________ + 2 _____________ ions
|Important Products = _______________, _________________, ___________________|
LIGHT INDEPENDENT REACTIONS (pg. 161-164)
- occur in the ___________________
- the Light Independent rxns do NOT directly require ______________ but do require the ______________ and _________________ produced in the Light Dependent Rxns
- in addition to these reactants (and many enzymes), the rxns require ________________________ from the air which enters the leaf through tiny openings called _____________________
- these reactions will produce ____________________
- also referred to as the "_______________ Cycle"
STEPS IN THE LIGHT INDEPENDENT REACTIONS
- The cycle begins with PHASE 1: "______________________ fixation" in which CO2 molecules combine with 5-carbon acceptor molecules called __________________________________ (RuBP). This produces 3-carbon molecules of __________________________________ (PGA). Because PGA has 3-carbons, the entire cycle is often called the ________ cycle. The enzyme ______________________ (ribulose bisphosphate carboxylase/oxygenase, the most abundant protein on Earth!) catalyzes this reaction.
- In PHASE 2: "Reduction Reactions" the PGA molecules are ________________________ by ATP to form ___________________________ (1,3 BPG). The 1,3 BPG molecules are then __________________ by NADPH and de_______________ to leave molecules of ___________________________________ (G3P).
- In PHASE 3: "RuBP Regeneration" molecules of G3P are phosphorylated by ATP to re-generate the intital __________ acceptor molecules. It takes two molecules of G3P to make one molecule of _______________. Thus, it takes ______ CO2 to make one glucose. The glucose can be:
a) converted into _____________________ for use as structural materials (ie. cell walls)
b) used in cellular ____________________ (plant cells have mitochondria)
c) stored as ____________________
|Important Product = _______________________|