Chapter 5, Problem 1Q

Summary Introduction

To analyze:

The result and describe the pathway that is followed by the protein by plotting a fluorescence intensity versus time graph with the help of the given table.

Given:

The green fluorescent protein (GFP) gene is fused with the gene of the viral protein. The normal cell is infected and the movement of the protein is monitored using fluorescence imaging equipment. The table shown below summarizes the result of the experiment:

Relative fluorescence intensity
Time (minutes)	Endoplasmic reticulum (ER)	Golgi	Cell membrane	Total
0	0.95	0.05	0.00	1.00
20	0.64	0.28	0.08	1.00
40	0.38	0.39	0.23	1.00
60	0.17	0.38	0.44	0.99
80	0.05	0.28	0.65	0.98
100	0.00	0.25	0.70	0.95
150	0.00	0.05	0.77	0.82
200	0.00	0.00	0.75	0.75

Introduction:

The GFP is a protein that fluoresces and is obtained from the aquatic animal called jellyfish, having the scientific name Aequorea victoria. It is made up of 238 amino acids. It emits green fluorescent light in the presence of ultraviolet light. GFP is used widely in biological techniques. For example, GFP gene is fused with the gene of the viral protein. The normal cell is then infected and the movement of the protein is monitored using fluorescence imaging equipment. This method is used to track the pathway that is traced by the protein.

Explanation of Solution

The graph of fluorescence intensity against time for the protein that is present in the ER is given below:

This graph depicts the intensity of fluorescence against time for the protein that is present in the ER. Initially, the fluorescence intensity is high, which means that the protein is entering the ER directly after synthesis. The graph plot is gradually decreasing, which is showing that the fluorescence in the ER is decreasing and reaching zero. This means that the fluorescent protein has moved out of the ER.

The graph of fluorescence intensity against time for the protein that is present in the Golgi apparatus is given below:

This graph depicts the intensity of fluorescence against time for the protein that is present in the Golgi apparatus. Initially, the fluorescence intensity is increasing, which means that the protein is entering the Golgi after a considerable time. The graph plot is gradually decreasing, which is showing that the fluorescence in the Golgi is decreasing and reaching zero. This means that the fluorescent protein is also moving out of the Golgi.

The graph of fluorescence intensity against time for the protein that is present in the cell membrane is given below:

This graph depicts the intensity of fluorescence against time for the protein that is present in the cell membrane. The fluorescence intensity is increasing gradually and is maximized after some time, which means that the protein is embedded in the cell membrane.

The pathway that is followed by the protein is traced with the help of the graphs drawn. The protein enters the ER quickly after synthesis and then goes to the Golgi. From the Golgi, it moves to the cell membrane to form virus particles.

Conclusion

Therefore, the graphs are plotted and the pathway of the GFP fusion protein is traced with the help of the graphs. The pathway followed by the protein is from ER to Golgi and then to the cell membrane.