Biology
THE KEY ROLES OF CELL DIVISION
The ability of organisms to reproduce best distinguishes living things from nonliving matter. The continuity of life is based on reproduction of cells, or cell division.
In unicellular organisms like amoeba, division of one cell reproduces the entire organism. Multicellular organisms depend on cell division for:
— Development from a fertilized cell
— Growth
— Repair
Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division.
CELL DIVISION RESULS IN GENETICALLY IDENTICAL DAUGHTER CELLS
Most cell division results in daughter cells with identical genetic information, DNA. Cell grows, splits in half, cell grows, splits in half and so on…. A special type of division produces nonidentical daughter cells (gametes, or sperm and egg cells, or spores).
CELLULAR ORGANIZATION OF THE GENETIC MATERIAL
All the DNA in a cell constitutes the cell’s genome. A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells) DNA molecules in a eukaryotic cell are pack aced into chromosomes.
Every eukaryotic species has a characteristic number of chromosomes in each nucleus. Humans have 46. Somatic cells (non reproductive cells) have two sets of chromosomes in most plants and animals. (Humans have two sets of 23) Gametes (reproductive cells: sperm and eggs, and spores) have hals as many chromosomes as somatic cells. (All of our gametes have 23 chromosomes) Eukaryotic chromosomes consist of chromatid, a complex of DNA and protein that condenses during cell division.
Eukaryotic cell division consists of:
— Mitosis, the division of the nucleus
— Cytokinesis, the division of the cytoplasm
Gametes and spores are produced by a variation of cell division called meiosis.
The ability of organisms to reproduce best distinguishes living things from nonliving matter. The continuity of life is based on reproduction of cells, or cell division.
In unicellular organisms like amoeba, division of one cell reproduces the entire organism. Multicellular organisms depend on cell division for:
— Development from a fertilized cell
— Growth
— Repair
Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division.
CELL DIVISION RESULS IN GENETICALLY IDENTICAL DAUGHTER CELLS
Most cell division results in daughter cells with identical genetic information, DNA. Cell grows, splits in half, cell grows, splits in half and so on…. A special type of division produces nonidentical daughter cells (gametes, or sperm and egg cells, or spores).
CELLULAR ORGANIZATION OF THE GENETIC MATERIAL
All the DNA in a cell constitutes the cell’s genome. A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells) DNA molecules in a eukaryotic cell are pack aced into chromosomes.
Every eukaryotic species has a characteristic number of chromosomes in each nucleus. Humans have 46. Somatic cells (non reproductive cells) have two sets of chromosomes in most plants and animals. (Humans have two sets of 23) Gametes (reproductive cells: sperm and eggs, and spores) have hals as many chromosomes as somatic cells. (All of our gametes have 23 chromosomes) Eukaryotic chromosomes consist of chromatid, a complex of DNA and protein that condenses during cell division.
Eukaryotic cell division consists of:
— Mitosis, the division of the nucleus
— Cytokinesis, the division of the cytoplasm
Gametes and spores are produced by a variation of cell division called meiosis.