Cell Cycles Flashcards
Do all multicellular organisms divide continuously?
Only some cells in multicellular organisms retain the ability to divide.
What type of cells undergo a normal cell cycle that is separated by periods of cell growth?
Cells that do not divide continuously in multicellular organisms.
How many stages does the cell cycle have?
3
What are the three stages of the cell cycle?
Interphase
Nuclear division
Division of the cytoplasm (cytokinesis)
How much of the cell cycle does interphase take up?
This occupies most of the cell cycle and it sometimes seen as the resting phase.
What happens during interphase?
No division takes place.
What happens in nuclear division?
The nucleus divides either into either two (mitosis) or four (meiosis).
What happens in cytokinesis?
This is where cytoplasm divides to produce two new cells (mitosis) or four new cells (meiosis).
What follows nuclear division?
Cytokinesis.
Are all cell cycles the same length?
No, the length of a complete cell cycle varies greatly amongst organisms.
How much time do mammalian cells tend to spend in interphase?
About 90%
What is the typical length of the mammalian cell cycle?
24 hours
What is cancer caused by?
A growth disorder of cells.
What does the growth disorder of cells lead to?
This leads to uncontrolled growth and division cells to create a tumour.
What does the tumour do?
It constantly grows in size.
Where can tumours develop?
They can develop in any organ in the body.
When does the tumour become cancerous?
It becomes cancerous if it changes from benign to malignant.
What is the rate of mitosis controlled by?
It is controlled by the environment of the cell and by growth factors. It is also controlled by two types of gene.
What results in uncontrolled mitosis?
A mutation in one of the two types of gene that controls growth.
How are mutant cells different from normal cells?
Mutant cells are usually structurally and functionally different from normal cells.
True or false: all mutant cells survive?
This is false, most mutated cells die however, any that survive are capable of dividing to form clones of themselves and form tumours.
What are the key features of malignant tumours?
They grow rapidly, they are less compact and they are more likely to be life-threatening.
What are the key features of benign tumours?
Benign tumours grow more slowly, are more compact and are less likely to be life-threatening.
What does the treatment of cancer often involve?
It often involves killing dividing cells by blocking a part of the cell cycle, this disrupts the cell division and therefore stops cancer growth.
How do drugs used to treat cancer usually disrupt the cell cycle?
They prevent DNA from replicating.
They inhibit the metaphase stage of mitosis by interfering with the spindle formation.
How do cancer drugs inhibit the metaphase stage of mitosis?
They interfere with the formation of spindle fibres.
What is the main problem with chemotherapy?
It also disrupts the cell cycle of normal cells.
What type of cells are cancer drugs more effective at stopping growth?
They are more effective against rapidly dividing cells. As cancer cells have a particularly fast rate of division, they are damaged to a greater degree than normal cells. Those normal cells such as hair-producing cells are also vulnerable to damage because they divide rapidly.
