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Ch 7 BIOOOo
Question | Answer |
---|---|
Which molecules don’t cross nuclear membrane | DNA |
Nuclear pores are made up of a group of proteins that are collectively called the nuclear pore complex | T |
Molecules pass into and out of the nucleus through nuclear pores | T |
The nuclear envelope is composed of two lipid bilayers | T |
The nuclear envelope is continuous with the Golgi apparatus | F |
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 | F |
A small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later What type of transport has taken place? | passive transport |
In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules? | 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 nucleu | Only one of the two fusion proteins possesses a nuclear localization signal. |
Molecules move into and out of the nucleus through the _____ | nuclear pore complexes |
Which organelle plays a role in intracellular digestion? | Lysosome |
Which statement most accurately describes what happens to proteins that lack an ER signal sequence? | They are released into the cytosol |
How are proteins transported throughout the endomembrane system? | The protein contains a molecular zip code that allows the protein to be shipped to the correct cellular compartment |
Pinocytosis | the cell is engulfing extracellular fluid |
What three distinct elements make up the cytoskeleton in eukaryotic cells? | actin filaments, intermediate filaments, and microtubules |
Which of the following would enable you to identify the plus end of actin filaments? | Add radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization. |
Common evolutionary origin for pro and eukaryotic flagella. | Eukaryotic flagella undergo an undulating motion and are covered by a plasma membrane; prokaryotic flagella move by rotating and lack a plasma membrane. |
Cellular homogenization is often incomplete, and the mixture has unbroken cells that are found in | pellet 1 (nuclei and whole cells) |
Histones (proteins) are found in | first pellet |
The preparation of liver mitochondrial enzymes begins by placing liver and a buffered solution in a blender.What is the purpose of the blender? | to prepare a cell homogenate; to break open the liver cells and to release the organelles |