Cell cycle Flashcards
What happens in Anaphase
The centromeres replicate so each sister chromatid has its own centromere. Spindle fibres contract, getting shorter, pulling sister chromatids apart to opposite poles of the cell
What happens in Prophase
Chromosomes become visible and are seen as 2 sister chromatids joined at the centromere. This is due to the DNA condensing , getting shorter and thicker. Centrioles move to opposite poles of the cell and nucleus starts to disappear.
What happens in Cytokinesis
The cell cytoplasm divides producing 2 daughter cells
what happens in Interphase
DNA replicated by Semi conservative Replication and all the organelles are duplicated
What happens in Metaphase
Spindle Fibres form from centromeres. Chromosomes attach to a separate spindle fibre by their centromere and are at the equator of the cell
What happens in Telophase
DNA de-condense, chromosomes are not visible, instead chromatin is present.Spindle fibres disintegrate and 2 nuclei reform. Now 1 cell 2 nuclei.
Why is Mitosis Important?
Growth
Tissue repair
Production of Genetically identical cells
What is step 1 in calculating mitotic index?
Count the number of cells undergoing mitosis (prophase, metaphase, anaphase and telophase)
What is step 2 in calculating mitotic index?
Count the total number of cells in the field of view
What is step 3 in calculating mitotic index?
Use the formula: Mitotic index in % = number of cells undergoing mitosis / total number of cells viewed x 100
What is the mitotic index formula?
Mitotic index in % = number of cells undergoing mitosis / total number of cells viewed x 100
What are the 4 stages of mitosis?
Prophase, Metaphase, Anaphase, Telophase
What is cancer?
Uncontrolled cell division
How can cancer occur?
When one of the genes that controls mitosis mutates causing rapid uncontrolled division often forming a tumor
What is binary fission?
Asexual reproduction of single celled organisms e.g. bacteria
