Question: Answer the following question given this paragraph: The Nuclear Envelope The nuclear envelope is a double-membrane structure that constitutes the outermost portion of the nucleus ( Figure 4.11). Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers. The nuclear envelope is punctuated with pores that control the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm. The nucleoplasm is the semi-solid fluid inside the nucleus, where we find the chromatin and the nucleolus. Chromatin and Chromosomes To understand chromatin, it is helpful to first consider chromosomes. Chromosomes are structures within the nucleus that are made up of DNA, the hereditary material. You may remember that in prokaryotes, DNA is organized into a single circular chromosome. In eukaryotes, chromosomes are linear structures. Every eukaryotic species has a specific number of chromosomes in the nuclei of its body's cells. For example, in humans, the chromosome number is 46, while in fruit flies, it is eight. Chromosomes are only visible and distinguishable from one another when the cell is getting ready to divide. When the cell is in the growth and maintenance phases of its life cycle, proteins are attached to chromosomes, and they resemble an unwound, jumbled bunch of threads. These unwound protein-chromosome complexes are called chromatin ( Figure 4.12); chromatin describes the material that makes up the chromosomes both when condensed and decondensed. Q: What is the double-membrane structure that constitutes the outermost portion of the nucleus? Choices: - energy fold - nuclear fold - energy envelope - nuclear envelope A:
Answer:
nuclear envelope