Question

regulation of the cell cycle – cancer notes
key concept - cell cycle __________ is necessary for healthy growth.
internal and __________ factors regulate cell division.

• external factors come from __________ the cell, such as nearby cells and from distant parts of the organism’s body.
• external factors include physical and chemical __________.
• one example of a physical signal is cell - to - cell contact.
• most mammal cells form a single layer in a culture dish and ________ dividing once they ________ other cells.

normal cell growth

• many cells also release chemical signals that tell other cells to __________ known as growth factors.
• growth factors are __________

Explanation:

To fill in the blanks, we use knowledge of cell cycle regulation:

1. Cell cycle regulation is necessary for healthy growth (as proper control of the cell cycle ensures normal development).
2. Internal and external factors regulate cell division (both internal like checkpoints and external like signals from other cells).
3. External factors come from outside the cell (they are not produced within the cell itself).
4. External factors include physical and chemical signals (these signals can be physical like cell - cell contact or chemical like growth factors).
5. Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells (this is contact inhibition, a normal regulatory mechanism).
6. Many cells also release chemical signals that tell other cells to divide (growth factors stimulate cell division).
7. Growth factors are proteins (they are a type of protein that acts as a signaling molecule to promote cell growth and division).

Answer:

1. regulation
2. external
3. outside
4. signals
5. stop; touch
6. divide
7. proteins