Podcast
Questions and Answers
What is the result of phosphorylating the RB protein?
What is the result of phosphorylating the RB protein?
- It becomes active and inhibits DNA replication
- It remains unchanged and continues to inhibit DNA replication
- It becomes inactive and can't inhibit DNA replication (correct)
- It becomes active and promotes DNA replication
In which phase of the cell cycle is cyclin A produced?
In which phase of the cell cycle is cyclin A produced?
- G2 phase
- S phase (correct)
- G1 phase
- M phase
What is the role of the cyclin B CDK-1 complex?
What is the role of the cyclin B CDK-1 complex?
- To activate mitosis (correct)
- To inhibit mitosis
- To inhibit DNA replication
- To activate DNA synthesis
What is the purpose of cyclin proteins in the cell cycle?
What is the purpose of cyclin proteins in the cell cycle?
What is the complex that phosphorylates the RB protein?
What is the complex that phosphorylates the RB protein?
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?
What is the main purpose of the regulation of the cell cycle?
What is the main purpose of the regulation of the cell cycle?
Where are the two key places of regulation in the cell cycle?
Where are the two key places of regulation in the cell cycle?
What do cyclin-dependent kinases (CDKs) do to other enzymes or proteins?
What do cyclin-dependent kinases (CDKs) do to other enzymes or proteins?
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?
What is required for a cyclin-dependent kinase (CDK) to be active?
What is required for a cyclin-dependent kinase (CDK) to be active?
What type of cyclins are produced in the G1 phase?
What type of cyclins are produced in the G1 phase?
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?
Why are specific cyclins produced at specific times in the cell cycle?
Why are specific cyclins produced at specific times in the cell cycle?
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.
