Monday, March 2, 2015

Photosynthesis

http://youtu.be/g78utcLQrJ4


Chloroplasts: Site where it occurs in Eukaryotes.

Thylakoid Membrane: Where the light reaction occurs

Granum: Stack of Thykaloids

Stroma: liquid in chloroplasts between Thykaloids where the Calvin Cycle occurs.

2 STEPS:
  1. Light Reactions: In Thylakoid membrane.  Water & light produce NADPH, ATP & 02 (waste).
  2. Calvin Cycle (a.k.a. Dark Reactions): In the Stroma.  Energy transfers where CO2 enters and Glucose comes out.
Essentially, PSII, Cyt B6f and PSI take electrons from light and put it through an electron transport chain.  (Protons are pumped into the inside of the Thylakoid called the Lumen).  ATP Synthase finishes the proton pumping process to make ATP.  Then ATP leaves and goes in the Stroma to the Calvin Cycle.  Waste Product: O2

Calvin Cycle: 5C molecule RUBP combines with CO2 through the leaf stromata, breaks into 2 3C molecules.  ATP adds energy in G3P to make useable sugars (sucrose, glucose, fructose and etc).

Problem: Photorespiration: occurs when we do not have enough CO2.  O2 jumps in and uses RuBisCo and makes junk (bad in all C3 plants).

Hot environments, CAM plants (pineapple)--only open stomata at night to avoid water loss.  Store CO2 in malic acid & enters the Calvin Cycle as they need it.  Stomatas can be closed during the day.  C4 (i.e corn) plants make 4C Oxalate which then moves to the bundle sheath cells, introduce CO2 to enter the Calvin Cycle.  Don't have to wait for CO2 to fuse in.

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