Mitosis & Meiosis Flashcards
What are the four phases the cell cycle has been created into>
G1 Phase - First Growth Phase
S Phase - Synthesis Phase
G2 Phase - Second Growth Phase
M Phase - Mitotic Phase
G1 Phase ( first growth phase)
The cell produces new proteins, grows and carries out its normal tasks for the body; this phase ends when the cell’s DNA begins to duplicate.
S Phase (synthesis phase)
The DNA molecules in the cell nucleus form extract copies of themselves
G2 Phase (Second growth phase)
This relatively short phase involve preparation for cell division.
M Phase (meiotic phase)
The cell divides into two daughter cells.
What does mitosis ensure?
It ensures that each body cell receives the exact same hereditary material (DNA) as that possessed by its parent cell.
What are the phases of mitosis?
Interphase Prophase Metaphase Anaphase Telophase
What happens in the interphase?
The cell goes through the G1, S and G2 phases of the cell cycle.
In the S phase, the DNA molecules in the nucleus form exact copies of themselves.
The DNA in the nucleus doubles.
What happens in Prophase?
(1st phase of mitosis)
Two pairs of centrioles become visible early in the prophase.
Centrioles move to opposite ends of the cell and microtubules begin to radiate from them.
At the same time, the nucleolus disappears and the nuclear membrane begins to break down.
Chromatin thread tightly coiled.
By the end, microtubules radiating from the centrioles join to a framework of ibres - spindle.
The chromatid pairs migrate toward the centre of the cell (nuclear membrane is gone).
What happens in Metaphase?
The chromatid pairs line up on the equator of the spindle. The centromere of each pair attached to a spindle.
What happens in the Anaphase?
Each pair of chromatids separate at the centromere = chromosomes.
New chromosomes are then pulled away from one another towards opposite poles of the cells.
Centromeres are still attached to the spindle fibres and the spindle fibres pull the chromosomes apart in some way.
What happens in Telophase?
The two sets of chromosomes form tight groups at each pole of the cell.
A nuclear membrane forms around each group.
A nucleolus appears in each new nucleus.
The spindle fibres disappear.
The chromosomes gradually uncoil to become chromatin threads once more.
What is cytokinesis?
It is the division of the cytoplasm.
A furrow develops in the cytoplasm between the two nuclei, this furrow gradually depends until it cuts the cytoplasm into two parts.
What is differentation?
It is the process by which cells become specialised.
Cells undergo division by mitosis, different genes become activated.
This makes the cells differentiate into specialised cells that can perform particular functions.
What are stem cells?
They are cells that can undergo differentiation
They are not specialised for any particular role and are capable of repeated division by mitosis.
Stem cells have the potential to develop into any cell type(specialised cells), under the right conditions.
