Cell Cycle
The cell cycle is all of the stages in the life of a cell, from the time the
cell is formed, to the time it divides into two new cells. The cell cycle is divided
into two major phases, which are interphase and the mitotic phase (m phase). In
the drawing, color the cell cycle (A) black, the interphase (B) dark blue, and the
mitotic phase (C) red.
Interphase is a period of growth and preparation. During interphase, the
cell is extremely active and carries on the regular routines of the cell. It is also
getting larger and preparing to divide into two new daughter cells. Interphase is
divided into three different sub-phases: G1 or Gap 1 phase, S or Synthesis
phase, and G2 or Gap 2 phase. During G1, the cell is making a lot of proteins and
is growing very rapidly. The cell’s organelles also increase in number and size.
Color the G1 phase (D) dark green. The second phase of interphase is the S
phase. During the S phase, DNA replication occurs. This means that the cell
makes an exact copy of its DNA so that when the cell divides, each new
daughter cell will have its own copy of DNA. The “S” in S phase stands for
synthesis, which means to create something new. In the S phase, a new
molecule of DNA that is exactly the same as the original is created. Color the S
phase (E) yellow. The third and last phase of interphase is the G2 phase. During
the G2 phase, the cell grows some more and gets ready to divide. Color the G2
phase of your drawing orange. Throughout interphase, the DNA is in the form of
chromatin.
After the G2 phase of interphase is complete, the cell enters the second
major phase of the cell cycle, which is the mitotic phase. The mitotic phase is
divided into two sub-phases: mitosis (H) and cytokinesis (G). Mitosis is the first
sub-phase of the mitotic phase. During mitosis, the chromosomes separate to
opposite sides of the cell. At the end of mitosis, the original nucleus has divided
into two new nuclei, but the rest of the cell has not completely divided yet.
Color the mitosis (H) brown. Mitosis is made up of four stages: prophase (H1),
metaphase (H2), anaphase (H3), and telophase (H4). You will learn more about
what happens during these four sub-phases later. Color prophase - light green,
metaphase - light blue, anaphase - purple, and telophase - pink. The second subphase of the mitotic phase, and the last phase of the entire cell cycle, is
cytokinesis. During cytokinesis, the cytoplasm of the cell divides and the cell
actually splits into two new cells. At the end of cytokinesis, the original cell,
called the mother cell, has completely divided into two new daughter cells. Each
daughter cell is identical to the original mother cell and to each other. Once
they have formed, each daughter cell will enter interphase and the cycle will be
repeated. Color cytokinesis gray. Color the mother cell and daughter cells any
colors you choose that have not yet been used!
1. Define the cell cycle in your own words.
2. What two main phases is the cell cycle divided into?
3. List the 3 sub-phases of interphase and briefly describe what happens in each
one.
4. What does the “S” of S phase stand for? Why is this a good name for this subphase of interphase?
5. What is the name of the phase in which the nucleus divides and chromosomes
move to opposite sides of the cell?
6. List the 4 stages of mitosis.
7. What happens during cytokinesis?
8. What happens to the daughter cells once they are created?
○ Cell cycle = A
○ Interphase = B
○ Mitotic Phase = C
○ G Phase = D
1
○ S Phase = E
○ G Phase = F
○ Cytokinesis = G
○ Mitosis = H
○ Mother Cell = a
2
○ Prophase = H
○ Metaphase = H
○ Anaphase = H
○ Telophase = H
○ Daughter Cells = b
1
2
3
4