Lecture 7

Question 1

What is the structure of chloroplast?

Answer 1

There are 2 membranes, an outer and inner membrane. Between these, there is the intermembrane space. Inside of the cell contains stroma, which is similar to the mitochondrial fluid matrix and is where the Calvin cycle occurs. There is also the thylakoid and thylakoid space, which is where the light reactions occur due to the thylakoid membrane having a large surface area. Chloroplast also contain DNA and ribosomes due its cyanobacteria origin.

Question 2

What are light reactions and how does it work?

Answer 2

In the thylakoid membrane, protein complexes called photo systems contain chlorophyll, which absorbs light energy –> energy transferred to electrons –> high energy electrons leave photosystem –> move through photosynthetic electron transport chain which is in thylakoid membrane, passing through protein complexes –> produces NADPH, O2, H+ gradient (from cytochrome complex) in the thylakoid space –> H+ gradient is used to turn ADP to ATP

Question 3

What is the first step of the Calvin cycle?

Answer 3

The first step is fixation. 3 x 5-carbon molecules + 3 x CO2 –> 6 x 3-carbon molecules.

Question 4

What is the second step of the Calvin cycle?

Answer 4

The second step is reduction. 6 x 3-carbon molecules (low energy) uses 6ATP and 6NADPH (from light reactions) to make 6 x 3-carbon molecules (high energy). One is taken out of the cycle as output, and the other 5 remain in Calvin cycle.

Question 5

What is the third step of the Calvin cycle?

Answer 5

The third step is regeneration. 3 ATP is used to convert 5 x 3-carbo molecules –> 3 x 5-carbon molecules so that they can be used for fixation again?

Question 6

What is the chemical formula for photosynthesis?

Answer 6

6CO2 + 6H2O –> C6H12O6 + 6O2

Question 7

What is endosymbiosis Theory?

Answer 7

proteobacteria –> mitochondria cyanobacteria –> chloroplasts