Question

The following problem describes an experiment, which in reality, would be very difficult to do, but imagine the experiment went perfectly for the purposes of this question. Plant cell cultures containing chloroplasts were labeled with [S]methionine for 60 minutes. In addition to [S]methionine, some cells were incubated with vehicle (Veh) and some cells were incubated with Drug F. The cells were then washed and collected for protein extraction specifically from chloroplasts. The chloroplasts were fractionated into sub-compartments, and protein extracts were separated by SDS-polyacrylamide gel electrophoresis, and autoradiography was performed. The gel image is shown below. - 1 2 3 4 5 6 IIIIIIIIIIIIII I TIL || UTII III OTTITILLIN Samples 1. Veh, whole chloroplast lysate 2. Veh, intermembrane space 3. Veh, stroma 4. Veh, thylakoid lumen 5. Drug F, intermembrane space 6. Drug F, stroma

If you somehow magically removed the chloroplast genome before doing this experiment, how would lanes 1-4 change? Justify your answer.

Computer typed, Please.

Answer 1

Answer. All lanes will be blank.

Justification

Chloroplast is an organelle which is responsible for photosynthesis in plants. Chloroplast has an inner and outer membrane with an empty intermediate space in between. Inside the chloroplast are stacks of thylakoids, called grana, as well as stroma, the dense fluid inside of the chloroplast. The thylakoids contain the chlorophyll pigments which are key molecule for photosynthesis. All the genes necessary for functioning of the chloroplasts and maintaining their structure are present in chloroplast genome. These DNA also contain the genes of ribosomal and transport RNA.

Thus, if chloroplast genome is removed before performing the experiment, there will be no synthesis of proteins responsible for chloroplast structure and function.