Chapter 4 Test Flashcards
Calvin cycle?
This stage combines carbon from carbon dioxide in the air and uses the chemical energy in ATP and NADPH to make glucose.
Light reactions?
This stage uses water and changes light energy from the sun into chemical energy stored I’m ATP and NADPH- stage releases oxygen as a waste product
Grana?
Chloroplasts contain this. Neat stacks
Consists of sac-like membranes known as thylakoid membranes.
Thylakoid membranes?
Sac-like membranes that contain photosystems.
Photosystems?
Groups of membranes that include chlorophyll
Chlorophyll?
Green pigment
Stroma?
The space outside the thylakoid membrane. Where the Calvin cycle takes place
What is the first stage of photosynthesis? And what are it’s steps?
Light reactions. 1.) photons strike a molecule of chlorophyll in photo system 2 of the thylakoid membrane. The light energy is absorbed by toe electrons in the chlorophyll molecules, giving them enough energy to leave the molecule.
2.) at the same time, enzymes in the thylakoid membrane use light energy to split apart a water molecule. This produces.. A.) two electrons. These replace the ones lost in step 1. B.) oxygen atom combines with another oxygen atom to be gas- waste product. C.) 2 + hydrogen ions released in thylakoid interior space.
3.) two electrons (energized) are carried by a series of electron transport molecules which make up electron transport chain. Energy is captured by moving from molecule to molecule and pump more hydrogen ions into the thylakoid membrane.
4.) electrons get to photosystem 1 in need of energy- they get energy from light which is absorbed by chlorophyll in ^^ - go back into chain.
5.) enzymes in the thylakoid membrane transfer the newly energized electrons to a compound called NADP+. Along with a hydrogen ion, this produces the energy-carrying molecule NADPH
6.)now, there is a greater concentration of hydrogen ions—and positive charge—in the thylakoid interior space difference in concentration and charge creates what is called a chemiosmotic gradient.
causes hydrogen ions to flow back across the thylakoid membrane to the stroma, where their concentration is lower. hydrogen ions have energy as they flow down The enzyme ATP synthase acts as a channel protein and helps the ions cross the membrane. ATP synthase also uses their energy to add a phosphate group (Pi) to a molecule of ADP, producing a molecule of ATP
Happens when stage 1 is done…
By the time Step 6 is finished, energy from sunlight has been stored in chemical bonds of NADPH and ATP. Thus, light energy has been changed to chemical energy, and thefirst stage of photosynthesis is now complete.
Steps of Calvin cycle
Step 1: Carbon Fixation. Carbon dioxide from the atmosphere combines with a simple, five-carbon compound called RuBP. This reaction occurs with the help of an enzyme named RuBisCo and produces molecules known as 3PG (a three-carbon compound, 3-Phosphoglyceric acid).
Step 2: Reduction. Molecules of 3PG (from Step 1) gain energy from ATP and NADPH (from the light reactions) and re-arrange themselves to form G3P (glycerate 3-phosphate). This molecule also has three carbon atoms, but it has more energy than 3PG. One of the G3P molecules goes on to form glucose, while the rest of the G3P molecules go on to Step 3.
Step 3: Regeneration. The remaining G3P molecules use energy from ATP to form RuBP, the five-carbon molecule that started the Calvin cycle. This allows the cycle to repeat.”
Summary of stage 2?
“The Calvin cycle takes over where the light reactions end. It uses chemical energy stored in ATP and NADPH (from the light reactions) and carbon dioxide from the air to produce glucose, the molecule that virtually all organisms use for food.
How to autotrophs produce food without using photosynthesis?
They use chemosynthesis ; where you use chemical energy instead of light energy.
Where do the stages of photosynthesis take place?
Both in the chloroplasts!
Calvin cycle in the stroma.
Light reactions take place in the thylakoid membranes.
