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The Process of Cell Division
Lesson Overview
Lesson
Overview
10.2 The Process
of Cell Division
The Process of Cell Division
Lesson Overview
Chromosomes
Chromosomes make it possible to separate DNA
precisely during cell division.
The genetic information that is passed on from one
generation of cells to the next is carried by
chromosomes.
Every cell must copy its genetic information before
cell division begins.
Each daughter cell gets its own copy of that genetic
information.
Cells of every organism have a specific number of
chromosomes.
mitosis
The Process of Cell Division
Lesson Overview
Prokaryotic Chromosomes
Prokaryotic cells lack nuclei. Instead, their DNA
molecules are found in the cytoplasm.
Most prokaryotes contain a single, circular DNA
molecule, or chromosome, that contains most of
the cell’s genetic information.
DNA unzips making 2 strands and each strand is copied
giving 2 identical copies of DNA.
The Process of Cell Division
Lesson Overview
Binary fission
Binary fission- Bacterial cell grows
and then splits into equal halves.
Product of binary fission – 2 identical
bacterial
The Process of Cell Division
Lesson Overview
Eukaryotic Chromosomes
In eukaryotic cells, chromosomes are
located in the nucleus, and are made
up of chromatin.
Chromatin is composed of DNA and
histone proteins.
The Process of Cell Division
Lesson Overview
DNA coils around histone proteins to form
nucleosomes
The nucleosomes interact with one
another to form coils and supercoils that
make up chromosomes.
The Process of Cell Division
Lesson Overview
The Eukaryotic Cell Cycle
Interphase consists of phases: G1, S, G2
Interphase is the time between cell
divisions.
G1 – rapid cell growth, a cell is in this
part
of the cell cycle for the longest period of
time
between cell divisions.
S – DNA is copied, chromosome
replicated
is now two sister chromatids joined at
centromere
The Process of Cell Division
Lesson Overview
G2 Phase: Preparing for Cell
Division
G2 – Organelles replicate,
microtubules are
reassembled to form spindle
apparatus that
will move chromosomes, cell is
now
prepared for mitosis.
This is the shortest phase of
interphase.
An eukaryotic cell spends most of
its time in
Interphase.
The Process of Cell Division
Lesson Overview
M Phase: Cell Division
In eukaryotes, cell
division occurs in two
stages: mitosis and
cytokinesis.
Mitosis is the division of
the cell nucleus.
Cytokinesis is the
division of the
cytoplasm.
After cytokinesis is
complete, the cell will be
in Interphase again.
The Process of Cell Division
Lesson Overview
MITOSIS
Biologists divide the events of mitosis
into
four phases:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
The Process of Cell Division
Lesson Overview
PROPHASE
Chromosomes condense and become
visible.
Centrioles form and take up positions
on opposite ends of the nucleus.
Spindle becomes visible.
Nuclear membrane breaks down, and
the nucleolus
disappears.
The Process of Cell Division
Lesson Overview
Metaphase
Spindle fibers (kinetochore) assist in moving
the chromosomes to the equator (middle)
of the cell.
The centromeres of all the sister chromatids
line up.
The imaginary line that bisects each of
the chromatids through the centromere
is called the metaphase plate.
The Process of Cell Division
Lesson Overview
ANAPHASE
Sister chromatids separate from each other
at the centromere.
The spindle now pulls each chromosome to
opposite ends of the cell (toward the
centrioles).
The spindle is taken apart as the
chromosomes move.
Each pole now has one complete set of
chromosomes.
The Process of Cell Division
Lesson Overview
TELOPHASE
Chromosomes uncoil, spindle fibers
disappear, and the nuclear
membrane reforms.
Mitosis is complete.
Is the cell divided???
The Process of Cell Division
Lesson Overview
Cytokinesis
Cytokinesis is the division of the cytoplasm.
Cytokinesis completes the process of cell
division – it splits one cell into two.
Animal cells pinch in the membranes forming
a cleavage furrow.
The Process of Cell Division
Lesson Overview
Cytokinesis in Plant Cells
In plants, the cell membrane is not flexible enough to
draw inward because of the rigid cell wall.
Instead, a cell plate forms between the divided
nuclei that develops into cell membranes.
The plate is formed from secretions of
the golgi.
A cell wall then forms in between the two new
membranes.
The Process of Cell Division
Lesson Overview
Important Cell Structures
Involved in Mitosis
Chromatin- genetic material in a non-dividing
cell, loose strands
Chromatid – each strand of a duplicated
chromosome
Centromere – the area where each pair of
chromatids is joined
Centrioles – tiny structures located in the
cytoplasm of animal cells that help organize the
spindle
Spindle – a fanlike microtubule structure that
helps separate the chromatids
The Process of Cell Division
Lesson Overview
The Stages of the Cell Cycle
mitosis review