Download Introduction to the Cell Cycle

Introduction
to the
Cell Cycle
Here’s what we’ll be
discussing in MUCH more
detail….
Limits to cell
growth
Why do cells divide?
Why don’t they just grow larger
and larger?
Problem #1.
Our DNA has it’s limits.
All of the information that a cell needs to function is
stored in it’s DNA.
• DNA is packaged into chromosomes. A chromosome
consists of one very long linear DNA molecule with
1000's of genes.
Our DNA has it’s limits!
• Each gene is the instructions for making a particular
protein that the cell needs.
• As the cell grows too large, there is an “information
crisis”. The DNA cannot keep up with the demands of
running a larger cell.
Problem #2. A Growing Cell Needs More Food
• A cell must constantly take in food and get rid of
waste.
• As the cell grows, the volume of the cell increases
much more rapidly than the surface area of the cell
membrane.
• When the cell gets too large, the membrane surface
area is not adequate enough to transport the large
quantities of food, water, and waste.
Cell Division
• Cell division is the process by
which a cell divides it’s contents
into two daughter cells.
1 mother cell  2 daughter cells
• The 2 daughter cells will be
IDENTICAL to the mother cell.
Chromosomes
• A cell must first copy it’s
chromosomes before
division can occur.
Chromosomes
• Chromosomes condense before
cell division occurs.
• After condensing and replicating,
the chromosomes consist of two
sister chromatids.
• These chromatids are connected
in the middle by a centromere.
The Cell Cycle
• The cell cycle is a series of
events that cells go through as
they grow and divide.
• During the cell cycle:
-A cell grows
-A cell prepares for division
-A cell divides into two
daughter cells
The Cell Cycle
The cell cycle consists of five major stages:
•
•
•
•
•
G1 (Gap 1)
S (Synthesis)
G2 (Gap 2)
Mitosis
Cytokinesis
Before a cell can begin mitosis, it must first do two
things…
1) Duplicate it’s DNA (chromosomes)
2) Duplicate a supply of organelles
This was a
CRASH COURSE
in what we will cover in this unit.
We will discuss all of these things in
detail.