In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?

In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?

1. To make the proteins bigger
2. To make the proteins easy to see
3. To give the protein molecules energy
4. To target the proteins to the nucleus

Answer: To make the proteins easy to see

Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results?

Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results?

1. The cytoplasmic protein contains a nuclear localization signal.
2. Nucleoplasmin does not have a nuclear localization signal.
3. One of the fusion proteins entered the nucleus by passive transport.
4. Only one of the two fusion proteins possesses a nuclear localization signal.

Answer: Only one of the two fusion proteins possesses a nuclear localization signal.

What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?

What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?

1. ER → lysosomes → vesicles that fuse with plasma membrane
2. nucleus → ER → Golgi
3. ER → Golgi → vesicles that fuse with plasma membrane
4. ER → Golgi → nucleus
5. Golgi → ER → lysosome

Answer: ER → Golgi → vesicles that fuse with plasma membrane

Which molecules do not normally cross the nuclear membrane?

Which molecules do not normally cross the nuclear membrane?

1. Proteins
2. Nucleotide triphosphates
3. DNA
4. mRNA

Answer: DNA

Which of the following statements about the nuclear envelope is false?

Which of the following statements about the nuclear envelope is false?

1. The nuclear envelope is composed of two lipid bilayers.
2. The nuclear envelope is continuous with the Golgi apparatus.
3. Molecules pass into and out of the nucleus through nuclear pores.
4. Nuclear pores are made up of a group of proteins that are collectively called the nuclear pore complex.

Answer: The nuclear envelope is continuous with the Golgi apparatus.

True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy.

True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy.

Answer: False