Exploring the Cell Cycle Control System

The video explains the cell cycle control system, highlighting the role of external signals like growth factors and internal molecules such as protein kinases and cyclins. It describes how these elements regulate cell division, ensuring proper growth and maintenance in eukaryotic organisms. The video also covers the mechanisms of signal transduction and the formation of cyclin-CDK complexes, which are crucial for cell cycle progression.

Why is cell division crucial in eukaryotic organisms?

• To increase the number of chromosomes

• To decrease the size of the cell

• For normal growth, development, and maintenance

• To remove old cells

What are growth factors?

• Proteins that regulate and coordinate cell proliferation

• Lipids that store energy

• Molecules that inhibit cell communication

• Enzymes that break down cell walls

How do growth factors typically act on nearby cells?

• Through paracrine signaling

• By direct contact

• Through long-range signaling

• By diffusing through the cell membrane

What is the role of transcription factors in cell proliferation?

• They inhibit cell division

• They break down proteins

• They control the rate of transcription of genetic information

• They encode growth factors

What are the two types of cell cycle regulatory molecules inside the cell?

• DNA and RNA

• Lipids and carbohydrates

• Protein kinases and cyclins

• Enzymes and hormones

How do protein kinases become active?

• By binding to DNA

• By associating with cyclins

• By breaking down ATP

• By increasing their concentration

What happens when a cyclin-dependent kinase (CDK) phosphorylates a target protein?

• The protein always becomes inactive

• The protein always becomes active

• The protein can either become active or inactive

• The protein is degraded

What is the result of the formation of a cyclin-CDK complex?

• The cell stops dividing

• The CDK acquires the ability to phosphorylate target proteins

• The cyclin is degraded

• The cell undergoes apoptosis

What is the role of cyclins in the cell cycle?

• They inhibit cell division

• They regulate the activity of CDKs

• They break down proteins

• They store genetic information

What is the final step in the cell cycle control system involving external and internal signals?

• The cell undergoes apoptosis

• Cyclins are synthesized and bind to CDKs

• The cell stops growing

• Growth factors are degraded