B4 - The Cell Cycle And Mitosis Flashcards
Why do cells divide?
To survive and grow.
What is the cell cycle? (Definition)
Body cells in multicellular organisms divide to produce new cells as part of a series of stages called the cell cycle.
What is mitosis?
The stage of the cell cycle when the cell divides.
What do multicellular organisms use mitosis for?
To grow (increasing the number of body cells)
To replace cells that have been damaged.
What is the result at the end of the cell cycle?
Two new identical cells to the original cell, with the same number of chromosomes.
Name the two main stages of the cell cycle.
Interphase and mitosis
Which stage takes the most time of the cell cycle?
The interphase.
Mitosis is a relatively small chunk of the cell cycle.
How is the DNA arranged in a cell that’s not dividing?
DNA is all spread out in long strings.
What happens to a cell before it divides?
The cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes.
During the interphase what happens after the cell has grown and increased the amount of subcellular structures?
It duplicates its DNA so there is one copy for each new cell.
What is formed when the DNA is duplicated?
X shaped chromosomes.
What is in the left and right arm of the duplicated DNA?
Each arm of the chromosome is an exact copy of the other.
In the cell cycle, what happens after the interphase?
Mitosis
What does mitosis produce?
Two new daughter cells, which contain exactly the same chromosomes.
What are the daughter cells genetically identical to?
The parent cell
Describe what happens in mitosis. 6
Chromosomes line up at the centre of the cell.
Cell fibres pull them apart.
The two arms of each chromosome go to opposite ends of the cell.
Membranes form around each of the sets of chromosomes.
These become nuclei of the new cells. (Nucleus has divided)
Cytoplasm and cell membranes divide.
What is the formula for estimating the number of cells there’ll be after multiple divisions of a cell block mitosis?
Number of cells = 2n (where n is the number of divisions by mitosis)
Why is the formula for number of cells after multiple divisions of a cell by mitosis only an estimate?
Because you can’t be sure the cells will keep diving at the same rate.
The rat of cell division is dependent on environmental conditions eg. lack of food could cause rate to decrease of some cells might die.
What is a random change in a gene called?
Mutation
What controls the rate at which cells divide by mitosis?
Genes
What may cause a cell to start dividing uncontrollably?
A change in one of the genes that controls cell division.
Cancer is a case of uncontrolled cell division.
What could be the result of uncontrolled cell division?
A mass of abnormal cells called a tumour.
When does a tumour become cancer?
If the tumour invades and destroys surrounding tissue.
What type of disease is cancer?
Non communicable
