.Essential idea: Cell division is essential but must be controlled
Understandings:
Mitosis is division of the nucleus into two genetically identical daughter nuclei.
Chromosomes condense by supercoiling during mitosis.
Cytokinesis occurs after mitosis and is different in plant and animal cells.
Interphase is a very active phase of the cell cycle with many processes occurring in the nucleus and cytoplasm.
Cyclins are involved in the control of the cell cycle.
Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours.
Applications and skills:
Application: The correlation between smoking and incidence of cancers.
Skill: Identification of phases of mitosis in cells viewed with a microscope or in a micrograph.
Skill: Determination of a mitotic index from a micrograph.
The stages in the cell cycle, including interphase (G1, S, G2), mitosis and cytokinesis.
INTERPHASE
The longest phase in the cycle
The cell carries out many biochemical reactions and grows larger
The DNA molecules are uncoiled, increase in the # of mitochondria and in chloroplasts (for plant cells)
G1: period of growth, DNA transaction & protein synthesis S phase: period during which all DNA in the nucleus is replicated G2: period which the cell prepares for division
MITOSIS & CYTOKINESIS
nucleus divides to form 2 genetically identical nuclei
2 cells are form, each containing 1 nucleus
Cytokinesis: process of dividing the cytoplasm to form 2 cells
Tumours (cancers) are the result of uncontrolled cell division and that these can occur in any organ or tissue.
The normal control of mitosis in a cell can fail, causing a change in the genes of the cell; when this cell divides in two, the daughter cells form four cells. The chain goes on and eventually the repeated uncontrolled divisions produce a tumor.
Tumors can happen in any organ and in any tissue
Tumors can spread around the body
Growth of tumors = CANCER
Phases of Mitosis :
Prophase
Metaphase
Anaphase
Telophase
USES OF MITOSIS Mitosis is used in in eukaryotes whenever genetically identical cells are needed:
During growth
during embryonic development, when the large cell produced by fertilization divides repeatedly to produce many smaller cells
when tissues have been damaged and need to be repaired