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Cells & Genes Essay - Eukaryotic cell cycle
Biological science (University of Oxford)
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Describe the eukaryotic cell cycle, discuss how it operates and is coordinated with cell growth,
and give examples of how its progression is regulated.
The Eukaryotic Cell Cycle
by Kylie Dong
Each cell undergoes a cell cycle in which is is created, grows, and then dies to make room for
new cells. The most basic function of the cell cycle is to copy the DNA in the cell, allow the cell
to grow, and then duplicate the cell into two identical daughter cells. The large number and
variety of proteins and hormones must regulate the stages of the cycle very carefully in order to
prevent errors (Alberts et al, 2002). Various signals also control the growth of cells themselves
in size and the number of cells in a particular tissue for example an embryo divides rapidly at
first, increasing it’s number of cells in order to increase in size. This is stimulated by particular
proteins that allow it to bypass the growth phases of the cell cycle so it can increase in cell
number quicker (Cooper, 2000).
Overview of cell cycle
The cell cycle consists of many stages. The two main stages
are interphase and mitosis. Within interphase there are two
growth phases, G1 and G2, with the S-phase/DNA synthesis or
replication occurring in between in preparation for mitosis.
Mitosis consists of 4 distinct stages: prophase, metaphase,
anaphase, telophase. This is followed closely by cytokinesis by
which the cells divides into two new cells and the cell cycle
begins again in each new cell. In a standard human body cell
rapidly dividing with a total cycle time of 24 hours, the G1
phase would last 11 hours, the S phase 8 hours, G2 phase 4
hours, and M phase 1 hour. The lengths of each stage can be
proven by an experiment in which cells are exposed to
radioactive thymidine then culture for varying lengths of time.
Radioactively labelled interphase cells will be observed for
several hours as they progress through the S-stage into the G2
stage. By comparison, radioactively labelled mitotic cells will
not be observed until 4 hours after labelling which corresponds
(Cliff, 2016)
to the length of the G2 stage, the minimum time required for a
cell to incorporate the radioactive thymidine at the end of S phase to enter mitosis (Cooper,
2000).
Mitosis
Mitosis is a large part of the cell cycle and is the process by which the DNA, organelles, and cell
itself divides into two new identical daughter cells. Mitosis begins with prophase when the
chromosomes are already replicated and each consists of two sister chromatids held together
by a centromere. These chromosomes condense in the nucleus. Outside the nucleus, the
Downloaded by olinder seth ()
Cells & Genes Essay - Eukaryotic cell cycle
Biological science (University of Oxford)
Scan to open on Studocu
Studocu is not sponsored or endorsed by any college or university
Downloaded by olinder seth ()
, lOMoARcPSD|59658805
Describe the eukaryotic cell cycle, discuss how it operates and is coordinated with cell growth,
and give examples of how its progression is regulated.
The Eukaryotic Cell Cycle
by Kylie Dong
Each cell undergoes a cell cycle in which is is created, grows, and then dies to make room for
new cells. The most basic function of the cell cycle is to copy the DNA in the cell, allow the cell
to grow, and then duplicate the cell into two identical daughter cells. The large number and
variety of proteins and hormones must regulate the stages of the cycle very carefully in order to
prevent errors (Alberts et al, 2002). Various signals also control the growth of cells themselves
in size and the number of cells in a particular tissue for example an embryo divides rapidly at
first, increasing it’s number of cells in order to increase in size. This is stimulated by particular
proteins that allow it to bypass the growth phases of the cell cycle so it can increase in cell
number quicker (Cooper, 2000).
Overview of cell cycle
The cell cycle consists of many stages. The two main stages
are interphase and mitosis. Within interphase there are two
growth phases, G1 and G2, with the S-phase/DNA synthesis or
replication occurring in between in preparation for mitosis.
Mitosis consists of 4 distinct stages: prophase, metaphase,
anaphase, telophase. This is followed closely by cytokinesis by
which the cells divides into two new cells and the cell cycle
begins again in each new cell. In a standard human body cell
rapidly dividing with a total cycle time of 24 hours, the G1
phase would last 11 hours, the S phase 8 hours, G2 phase 4
hours, and M phase 1 hour. The lengths of each stage can be
proven by an experiment in which cells are exposed to
radioactive thymidine then culture for varying lengths of time.
Radioactively labelled interphase cells will be observed for
several hours as they progress through the S-stage into the G2
stage. By comparison, radioactively labelled mitotic cells will
not be observed until 4 hours after labelling which corresponds
(Cliff, 2016)
to the length of the G2 stage, the minimum time required for a
cell to incorporate the radioactive thymidine at the end of S phase to enter mitosis (Cooper,
2000).
Mitosis
Mitosis is a large part of the cell cycle and is the process by which the DNA, organelles, and cell
itself divides into two new identical daughter cells. Mitosis begins with prophase when the
chromosomes are already replicated and each consists of two sister chromatids held together
by a centromere. These chromosomes condense in the nucleus. Outside the nucleus, the
Downloaded by olinder seth ()
