What is DNA?
The genetic material
located in the nucleus of the
cell. It contains information
needed for an organism to
grow, maintain itself, and
reproduce.
What is a chromosome?
The physical structure in a
cell that contains the
cell’s genetic material. It
is compacted DNA.
How many chromosomes
do humans have?
Every species has a specific
number of chromosomes. For
humans it is 46 total
chromosomes or 23 pairs.
Mom = 23 chromosomes
Dad = 23 chromosomes
Total = 46 chromosomes
What is the relationship
between DNA and
chromosomes?
Nucleus Chromosomes
DNA
Why do cells need to
divide?
Growth: Baby sea turtle growing
into an adult sea turtle.
Development: Cells develop
into specific cells like skin cells.
Repair: Broken bone in your
body will repair itself.
How do cells divide?
Cells have a life cycle called the
cell cycle. The cell cycle is the
development and division of a
cell. There are 2 main phases:
 Interphase
 Mitosis
What does the Cell
Cycle look like?
Cell Cycle = Interphase, Prophase,
Metaphase, Anaphase, Telophase
What happens during
Interphase?
 The
cell spends
90% of its time in
this phase.
 The cell is
growing and is
ready to divide.
 At the end, the
nucleus contains
2 copies of DNA.
What happens during
Prophase?
The nuclear membrane
disappears.
 Chromosomes become
visible.
 Centrioles move to
opposite sides of the
nucleus and microtubules
appear.
 The cell prepares to
divide.

What happens during
Metaphase?
 Chromosomes
line up in the
middle of the
cell.
What happens during
Anaphase?
 Chromatids
of each
chromosome
pull apart
and move to
the opposite
ends of the
cell.
What happens during
Telophase?
2 new nuclear
membranes form.
 In plants, the cell
plate forms which
will become the cell
wall.
 Cell pinches and
divides.

What happens during
Cytokinesis?
Cell pinches and divides.
 Not a phase of mitosis, but must
occur for cell division to be
complete.
 Cyto- = cell and -Kinesis = movement
