The cell cycle, mitosis and meiosis
Learning objective
This learning material is about the life cycle of a cell and the series of stages by which
genetic materials are duplicated and partitioned to produce two daughter cells with the same
genetic component as the parent cell.
The cell cycle
Actively dividing eukaryote cells pass through a series of stages known collectively as the
cell cycle: two gap phases (G1 and G2); an S (for synthesis) phase, in which the genetic
material is duplicated; and an M phase, in which mitosis partitions the genetic material and
the cell divides.
G1 phase. Metabolic changes prepare the cell for division. At a certain point - the restriction
point - the cell is committed to division and moves into the S phase.
S phase. DNA synthesis replicates the genetic material. Each chromosome now consists of
two sister chromatids.
G2 phase. Metabolic changes assemble the cytoplasmic materials necessary for mitosis and
cytokinesis.
M phase. A nuclear division (mitosis) followed by a cell division (cytokinesis).
The period between mitotic divisions - that is, G1, S and G2 - is known as interphase.
, Mitosis
Mitosis is a form of eukaryotic cell division that produces two daughter cells with the same
genetic component as the parent cell. Chromosomes replicated during the S phase are divided
in such a way as to ensure that each daughter cell receives a copy of every chromosome. In
actively dividing animal cells, the whole process takes about one hour.
The replicated chromosomes are attached to a 'mitotic apparatus' that aligns them and then
separates the sister chromatids to produce an even partitioning of the genetic material. This
separation of the genetic material in a mitotic nuclear division (or karyokinesis) is followed
by a separation of the cell cytoplasm in a cellular division (or cytokinesis) to produce two
daughter cells.
In some single-celled organisms mitosis forms the basis of asexual reproduction. In diploid
multicellular organisms sexual reproduction involves the fusion of two haploid gametes to
produce a diploid zygote. Mitotic divisions of the zygote and daughter cells are then
responsible for the subsequent growth and development of the organism. In the adult
organism, mitosis plays a role in cell replacement, wound healing and tumour formation.
Mitosis, although a continuous process, is conventionally divided into five stages: prophase,
prometaphase, metaphase, anaphase and telophase.
Learning objective
This learning material is about the life cycle of a cell and the series of stages by which
genetic materials are duplicated and partitioned to produce two daughter cells with the same
genetic component as the parent cell.
The cell cycle
Actively dividing eukaryote cells pass through a series of stages known collectively as the
cell cycle: two gap phases (G1 and G2); an S (for synthesis) phase, in which the genetic
material is duplicated; and an M phase, in which mitosis partitions the genetic material and
the cell divides.
G1 phase. Metabolic changes prepare the cell for division. At a certain point - the restriction
point - the cell is committed to division and moves into the S phase.
S phase. DNA synthesis replicates the genetic material. Each chromosome now consists of
two sister chromatids.
G2 phase. Metabolic changes assemble the cytoplasmic materials necessary for mitosis and
cytokinesis.
M phase. A nuclear division (mitosis) followed by a cell division (cytokinesis).
The period between mitotic divisions - that is, G1, S and G2 - is known as interphase.
, Mitosis
Mitosis is a form of eukaryotic cell division that produces two daughter cells with the same
genetic component as the parent cell. Chromosomes replicated during the S phase are divided
in such a way as to ensure that each daughter cell receives a copy of every chromosome. In
actively dividing animal cells, the whole process takes about one hour.
The replicated chromosomes are attached to a 'mitotic apparatus' that aligns them and then
separates the sister chromatids to produce an even partitioning of the genetic material. This
separation of the genetic material in a mitotic nuclear division (or karyokinesis) is followed
by a separation of the cell cytoplasm in a cellular division (or cytokinesis) to produce two
daughter cells.
In some single-celled organisms mitosis forms the basis of asexual reproduction. In diploid
multicellular organisms sexual reproduction involves the fusion of two haploid gametes to
produce a diploid zygote. Mitotic divisions of the zygote and daughter cells are then
responsible for the subsequent growth and development of the organism. In the adult
organism, mitosis plays a role in cell replacement, wound healing and tumour formation.
Mitosis, although a continuous process, is conventionally divided into five stages: prophase,
prometaphase, metaphase, anaphase and telophase.
