CELL DIVISION & CELL CYCLE – THE CONTINUATION OF LIFE
Life on the earth is due to Cell division & cell cycle. Different phases of Cell division & Cell Cycle are described below:
· The earth is teeming with countless living cells.
· You have 100 trillion cells in your body alone.
· They are …. you.
· Cell comes in all sizes and shapes.
· They perform thousands of different tasks in the life forms of earth.
· They work together to form the tissues of all living things.
· But cell don’t live forever. Eventually they die.
· Fortunately, they have ability to reproduce through a process called cell division.
· It begins a chemical signal to prepare for reproduction. The cell grows larger. It is called “G1 Phase” of cell’s life.
· After growth, the cell duplicates it s DNA. This is called the “S Phase” of the cell cycle.
· The DNA is then checked by enzymes for mistakes & repaired. This is “G2 Phase” of cell cycle.
· When ready cell division begins . It is called “Mitosis” and the cell division.
· Mitosis begins when the nuclear membrane dissolves and DNA thickens called (Prophase).
· Special fibers called spindle fibers form on each end of the cell and grow towards the DNA chromosomes.
· The fiver then attach to centromeres on the chromosomes and pull them into a line in the middle of the cell called (Metaphase).
· The chromosomes are pulled apart by the spindle fibers to opposite sides of the cell called (Anaphase).
· Lase is Telophase. Two new nuclei form the cell and then divides in two called Cytokines.
· all of us started life as single cell that divided again and again.
· But the first cell experienced something special… SEX.
· The cells involved in SEX are produced by a process called Meiosis.
· Cell division & cell cycle – the continuation of life.