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Questions and Answers
What is the result of phosphorylating the RB protein?
What is the result of phosphorylating the RB protein?
In which phase of the cell cycle is cyclin A produced?
In which phase of the cell cycle is cyclin A produced?
What is the role of the cyclin B CDK-1 complex?
What is the role of the cyclin B CDK-1 complex?
What is the purpose of cyclin proteins in the cell cycle?
What is the purpose of cyclin proteins in the cell cycle?
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What is the complex that phosphorylates the RB protein?
What is the complex that phosphorylates the RB protein?
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What is the result of having cyclin proteins present during the cell cycle?
What is the result of having cyclin proteins present during the cell cycle?
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What is the main purpose of the regulation of the cell cycle?
What is the main purpose of the regulation of the cell cycle?
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Where are the two key places of regulation in the cell cycle?
Where are the two key places of regulation in the cell cycle?
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What do cyclin-dependent kinases (CDKs) do to other enzymes or proteins?
What do cyclin-dependent kinases (CDKs) do to other enzymes or proteins?
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What is the default form of cyclin-dependent kinases (CDKs) in a cell?
What is the default form of cyclin-dependent kinases (CDKs) in a cell?
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What is required for a cyclin-dependent kinase (CDK) to be active?
What is required for a cyclin-dependent kinase (CDK) to be active?
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What type of cyclins are produced in the G1 phase?
What type of cyclins are produced in the G1 phase?
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What is the function of the complex formed by CDK-2 and cyclin E?
What is the function of the complex formed by CDK-2 and cyclin E?
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Why are specific cyclins produced at specific times in the cell cycle?
Why are specific cyclins produced at specific times in the cell cycle?
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Study Notes
Cell Cycle Regulation
- The cell cycle is a regulated process with two key checkpoints: one between G1 and S phase, and another between G2 and mitosis.
- Cyclin-dependent kinases (CDKs) are key regulators of the cell cycle, and they work together with cyclin proteins.
- CDKs are always present in cells, but they are inactive by default and need to be activated by cyclin proteins.
- Specific cyclins are produced at specific times in the cell cycle, and CDKs are only active when bound to a specific cyclin.
G1 Phase
- Cyclins D and E are produced in the G1 phase.
- CDK-2 binds to cyclin E, and CDK-4 binds to cyclin D, forming active kinase complexes.
- The CDK-4 cyclin D complex phosphorylates the RB protein, inactivating it and allowing DNA replication to proceed.
S Phase
- Cyclin A is produced in the S phase.
- Cyclin A complexes with CDK-2 to activate DNA replication.
G2 Phase
- Cyclin B is produced in the G2 phase.
- The cyclin B CDK-1 complex is formed, which activates mitosis or cell division.
Checkpoints
- The presence of specific cyclin proteins is necessary to pass through the checkpoints and allow the cell cycle to proceed.
- Cyclin proteins inhibit proteins that block DNA synthesis or replication, and promote the production of proteins needed for mitosis.
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Description
Learn about the regulation of the cell cycle, including the two key checkpoints and the role of cyclin-dependent kinases (CDKs) and cyclin proteins.
