Transcript Cell Division

Cell Division
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Why do we grow? Do our cells
get bigger?

NO: organisms grow because they produce
more cells, not larger ones.
 A baby’s cells are the same size as an
adult’s, there are just less of them.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Cell division

Before a cell grows too large, it divides into two
“daughter cells.”
 Before it divides, it must copy its genetic material
so that both new daughter cells have a complete
set of DNA.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Chromosomes: coiled up DNA

Located in the nucleus
 Become visible ONLY during cell division
 Organisms have different numbers of them:
humans have 46.
The cell cycle:
Interphase:

G1 phase: cell growth


S phase: DNA replication


Cells increase in size, make
new proteins & organelles
Chromosomes are copied,
new DNA molecules made
G2 phase: preparation for
mitosis

Shortest phase, organelles
&molecules needed for
mitosis are made
M phase (MITOSIS): division of
the nucleus and cytoplasm
into two daughter cells
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Mitosis phases: PMAT
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Prophase

QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
First/longest phase (5060% of total time to do
mitosis)
 Chromosomes become
visible
 Centrioles separate and
position at opposite ends
of the cell
 Spindle fibers form
 Chromosomes attach to
the spindle fibers
 Nuclear envelope breaks
down
Metaphase

Lasts only minutes
 Chromosomes line up in the center of the cell
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Anaphase

Copied chromosomes separate and begin to
move toward opposite ends of the cell
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Telophase



Chromosomes disperse --become a tangle of material
rather than distinct chromatids
Nuclear envelopes begin to form around each clump of
chromosomes
Spindles break apart
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Cytokinesis (very end of
Telophase)

Cytoplasm divides
 In animals the cell membrane pinches in
 In plants a new cell wall forms
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Mitosis Poster

Copy figure 10-5 on pages 246-247 in your
book onto a large poster paper
 Draw each stage//copy what is happening
to the cell at each stage
 Must use color