When cells touch
Normal cells stop dividing on contact. Cancer cells do not.
Knowing when to stop
Cells in a dish divide and spread out until they fill the dish.
What do you think many animal cells do when they touch their neighbours?
What this lesson covers
The idea
In many animal cells, division stops when cells come in contact with neighbouring cells (contact inhibition); cancer cells lose this control and divide uncontrollably, forming tumours, while plant cells, with rigid walls, show no contact inhibition.
Knowing when to stop
Cells in a dish divide and spread out until they fill the dish.
What do you think many animal cells do when they touch their neighbours?
- They stop dividing
- They divide even faster
- They turn into plant cells
Fill the dish
Run time forward for normal animal cells, cancer cells, and plant cells.
Contact inhibition
In many animal cells, division usually stops when cells come in contact with neighbouring cells. This is called contact inhibition. Cancer cells lose this control and keep dividing uncontrollably, forming tumours. Plant cells have rigid cell walls, so they do not show contact inhibition and follow a different pattern of growth.
Cancerous tumours can invade nearby tissues and even spread to other parts of the body to form new tumours.
- Cells | On touching neighbours
- Normal animal cells | division stops (contact inhibition)
- Cancer cells | keep dividing; form a tumour
- Plant cells | no contact inhibition; different growth pattern
Notes
Many animal cells stop dividing when they touch neighbouring cells: contact inhibition. Cancer cells lose it and divide uncontrollably, forming tumours. Plant cells, with rigid walls, show no contact inhibition.
Check yourself
What is contact inhibition?
Which cells lose contact inhibition and keep dividing uncontrollably?
Why do plant cells not show contact inhibition?
- Division stops when cells touch their neighbours — correct. Yes.
- Cells divide faster when they touch. It is the opposite.
- Cells die when they touch. Division stops; the cells do not die.
- Cancer cells — correct. Yes. They form tumours.
- Normal skin cells. They stop dividing on contact.
- Dead cells. Dead cells do not divide.
- Their rigid cell walls: they follow a different pattern of growth — correct. Yes.
- They have no nucleus. They have a nucleus.
- They never divide. Plant cells divide.