IB Biology Topic D2.1: Cell and Nuclear Division Key Definitions

The cell cycle is a series of stages that a cell goes through to grow, replicate its DNA, and divide into two daughter cells.

The rapid increase in cell numbers through division, occurring at a faster rate than cell death.

A group of proteins that regulate the cell cycle by activating cyclin-dependent kinases (CDKs).

Cytokinesis is the process of dividing the cytoplasm of a parent cell into two daughter cells.

DNA replication is the biological process by which a cell copies its DNA to ensure that each daughter cell receives an identical set of genetic instructions during cell division. It is essential for growth, repair, and reproduction in living organisms.

The genome is the complete set of genetic instructions that determines the structure, function, and traits of an organism.

Meiosis is a type of cell division that reduces the chromosome number by half, producing four genetically distinct haploid cells. This process occurs in gamete-producing cells and is essential for sexual reproduction.

Mitosis is a type of cell division in which a single parent cell divides to produce two genetically identical daughter cells, each containing the same number of chromosomes as the parent cell.

The mitotic index is the ratio of the number of cells in mitosis to the total number of cells observed.

The failure of homologous chromosomes or sister chromatids to separate properly during meiosis.

A nucleosome is the basic structural unit of chromatin, consisting of DNA wrapped around a core of histone proteins.

Proto-oncogenes are normal genes that act as the cell’s accelerator, promoting cell division when needed.

When each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.

Stem cells are undifferentiated cells with the unique ability to divide endlessly and differentiate into various specialized cell types.

A tumour is an abnormal mass of cells resulting from uncontrolled cell division.

A eukaryotic cell formed by the fusion of two gametes.