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5.1 The Cell Cycle
Why do you think that you
always have to cut your hair,
your fingernails, and the
The growth is made by new
cells being made.
5.1 The Cell Cycle
Cells have distinct phases of growth, reproduction,
and normal functions.
5.1 The Cell Cycle
5.1 The Cell Cycle
Your body cells go through a cycle too. This cycle allows
new cells to be created to heal or replace dead or
damaged cells.
5.1 The Cell Cycle
• The cell cycle is a regular pattern of growth, DNA
replication, and cell division that occurs in eukaryotic cells.
• The cell cycle
is the process
of duplicating
somatic or
body cells
5.1 The Cell Cycle
STAGE 1- Gap 1 (G1)
•Cells carry out their normal functions
•Cells increase in size
•Organelles increase in number
* Cells spend most of their time here
5.1 The Cell Cycle
STAGE 2- Synthesis (S)
•Cell makes a copy of its nuclear DNA
•By the end of S stage the cell contains 2
complete sets of DNA
5.1 The Cell Cycle
STAGE 3- Gap (G2)
•Cells continue to carry out their normal functions
•Additional growth occurs
5.1 The Cell Cycle
STAGE 4 (includes 2 processes)
•The division of a body cell’s nucleus and its
•2 new nuclei form
•The process that divides the cell cytoplasm
5.1 The Cell Cycle
5.1 The Cell Cycle
The result of the cell cycle is 2
daughter cells that are identical to the
original cell
5.1 The Cell Cycle
Cells divide at different rates.
• The rate of cell division varies with the need for those
types of cells.
• Some cells are unlikely to divide (G0).
5.1 The Cell Cycle
Cell size is limited.
• Volume increases faster than surface area.
5.1 The Cell Cycle
• Surface area must allow for adequate
exchange of materials.
– Cell growth is coordinated with
– Cells that must be large have
unique shapes.