Module 2 Section 6 - The Cell Cycle and Mitosis Flashcards
What is the cell cycle
The process that all body cells in multicellular organisms use to grow and divide
When does the cell cycle start
When a cell has been produced by cell division
When does the cell cycle end
It ends with the cell dividing to produce two identical cells
What does the cell cycle consist of
Interphase (Cell growth and DNA replication)
M Phase (Mitosis and cytokinesis)
Interphase is divided into 3 stages what are they
G1 (gap phase 1), S (synthesis), G2 (gap phase 2)
What happens in gap phase 1
In gap phase 1 the cell grows and new organelles and proteins are made
How is the cell cycle regulated
By checkpoints
When do checkpoints occur
At key points during the cycle to make sure it’s ok for the process to continue
What happens after g1
The cell undergoes checks at the g1 checkpoint
What does the g1 checkpoint check for
Checks that the chemicals needed for replication are present and checks for damage to the DNA before enter S-phase
After passing the g1 checkpoint what happens to a cell in the cell cycle
The cell enters synthesis phase
What happens in the synthesis phase in the cell cycle
The cell replicates it’s DNA ready to divide by mitosis
What happens to the cell after synthesis stage
It enters g2 (gap phase 2)
What happens in g2
Cell keeps growing and proteins needed for cell division are made
What happens after g2
The cell has to clear the g2 checkpoint
What does the g2 checkpoint check for
The cell checks whether all the DNA has been replicated without any damage
What happens after the cell clears the g2 checkpoint
It enters m-phase
What happens in m-phase
The cell goes through mitosis and cytokinesis
What happens to the cell after m-phase
It has to pass through the metaphase checkpoint
Where does interphase start
G1
Where does interphase end
G2 checkpoint
How many stages does mitosis have
4 stages
Why is mitosis needed
Mitosis is needed for growth of multicellular organisms and for repairing damaged tissues
What are the stages of mitosis in order
Prophase
Metaphase
Anaphase
Telophase
What happens before mitosis
Interphase
What happens to the cell in interphase
The cell prepares for division
The cell’s DNA will unravel and replicate to double its genetic content
Organelles are replicated so it has spare ones
ATP content is increased so it provides energy needed for cell division
What happens to the cell in the prophase stage of mitosis
Chromosomes condense (get shorter and fatter)
Centrioles move to opposite ends of the cell
Network of protein fibres form, called the spindle
Nuclear envelope breaks down, DNA lies free in cytoplasm
What happens to the cell in the metaphase stage of mitosis
The chromosomes (each with 2 Chromatids) line up along the middle of the cell
They attach to the spindle by their centromere
What happens at the metaphase checkpoint
The cell checks that all the chromosomes are attached to the spindle before mitosis can continue
What happens to the cell in the anaphase stage of mitosis
The centromere divide - each pair of sister chromatids are separated
The spindles contract pulling chromatids to the opposite ends of the cell, centromere first
What happens to the cell in the telophase stage of mitosis
The chromatids reach the opposite poles on the spindle
They uncoil and become long and thin again - called chromosomes again
Nuclear envelope forms around each group of chromosomes, now 2 nuclei
What happens in cytokinesis
The cytoplasm divides
In animal cells, cleavage furrow forms to divide the cell membrane
There are now two daughter cells (genetically identical to the original)
When does cytokinesis start
Usually begins in anaphase
When does cytokinesis end
Telophase
As mitosis begins the chromosomes are made of what
2 separate strands called chromatids
1 centromere
How can you observe the cell cycle
By staining chromosomes
