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Questions and Answers
What is the main function of the nucleus in a cell?
What is the main function of the nucleus in a cell?
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What happens to the nucleus during cell division?
What happens to the nucleus during cell division?
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What is the function of the nuclear envelope?
What is the function of the nuclear envelope?
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Where is the perinuclear space located?
Where is the perinuclear space located?
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What is the main function of nuclear pores?
What is the main function of nuclear pores?
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How many nuclear pores does a typical mammalian cell contain in its nuclear envelope?
How many nuclear pores does a typical mammalian cell contain in its nuclear envelope?
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What is found in the nuclear interior?
What is found in the nuclear interior?
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What is the function of the inner nuclear membrane?
What is the function of the inner nuclear membrane?
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What is nucleoplasm also known as?
What is nucleoplasm also known as?
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'Nuclear lamina' is attached to which part of the nucleus?
'Nuclear lamina' is attached to which part of the nucleus?
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What is the space between the inner and outer membrane of the nuclear envelope called?
What is the space between the inner and outer membrane of the nuclear envelope called?
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What are the perforations that span the whole nuclear envelope called?
What are the perforations that span the whole nuclear envelope called?
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What is the main function of the central transport channel in nuclear pores?
What is the main function of the central transport channel in nuclear pores?
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What is the role of importins and exportins in the nuclear pore complex?
What is the role of importins and exportins in the nuclear pore complex?
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What is the function of the nuclear lamina in the nucleus?
What is the function of the nuclear lamina in the nucleus?
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During which phase of the mitotic division does the dissolution of nuclear envelope occur?
During which phase of the mitotic division does the dissolution of nuclear envelope occur?
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What is found in the nuclear interior?
What is found in the nuclear interior?
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What is the main function of nucleoli in the nucleus?
What is the main function of nucleoli in the nucleus?
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Where are the genes for 5.8S, 18S, and 28S rRNAs located in humans?
Where are the genes for 5.8S, 18S, and 28S rRNAs located in humans?
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What happens to nucleoli at the beginning of mitosis?
What happens to nucleoli at the beginning of mitosis?
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What is the function of nuclear speckles in the nucleus?
What is the function of nuclear speckles in the nucleus?
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Where are 5S rRNA genes located in humans?
Where are 5S rRNA genes located in humans?
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What happens to ribosomal proteins after they are synthesized in cytoplasm?
What happens to ribosomal proteins after they are synthesized in cytoplasm?
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What determines the size of nucleoli in a cell?
What determines the size of nucleoli in a cell?
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Study Notes
Nucleus Structure and Function
- The main function of the nucleus is to control cell growth and reproduction by storing genetic information.
- During cell division, the nucleus splits into two identical nuclei, each with a complete copy of the genetic material.
Nuclear Envelope
- The nuclear envelope is a double membrane structure that surrounds the nucleus.
- The nuclear envelope is perforated with nuclear pores, which allow for the exchange of molecules between the nucleus and cytoplasm.
- The nuclear envelope has a perinuclear space located between the inner and outer membranes.
- The nuclear envelope contains approximately 3,000-4,000 nuclear pores in a typical mammalian cell.
Nuclear Pores and Transport
- Nuclear pores are large protein complexes that span the entire nuclear envelope, allowing for the exchange of molecules between the nucleus and cytoplasm.
- The main function of nuclear pores is to regulate the transport of molecules in and out of the nucleus.
- The central transport channel in nuclear pores is responsible for the selective transport of molecules.
- Importins and exportins are proteins that play a crucial role in the nuclear pore complex, facilitating the transport of molecules into and out of the nucleus.
Nuclear Interior and Components
- The nuclear interior is composed of nucleoplasm, also known as karyoplasm.
- The nuclear lamina is a protein network attached to the inner nuclear membrane.
- The nucleoplasm contains nucleoli, which are regions of RNA synthesis and ribosome assembly.
- The nucleoplasm also contains nuclear speckles, which are regions of RNA processing and splicing.
Nucleoli and Ribosome Synthesis
- Nucleoli are responsible for the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomes.
- In humans, the genes for 5.8S, 18S, and 28S rRNAs are located in the nucleoli.
- At the beginning of mitosis, nucleoli are dispersed and reassemble during telophase.
- The size of nucleoli is determined by the amount of rRNA synthesis.
Ribosome Synthesis and Assembly
- Ribosomal proteins are synthesized in the cytoplasm and then transported to the nucleus for assembly into ribosomes.
- The 5S rRNA genes are located in the nucleoplasm, separate from the genes for 5.8S, 18S, and 28S rRNAs.
Mitosis and Nuclear Envelope
- During the prophase of mitotic division, the nuclear envelope dissolves, releasing the chromatin into the cytoplasm.
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Description
This quiz covers the structure and function of the cell nucleus, including its parts such as the nuclear envelope, nuclear lamina, nucleoplasm, chromatin, and nuclear bodies. It also discusses the role of the nucleus as the storage site for genetic information and its significance as the control center of the cell.
