Objectives
1) Name three parts of the cell cycle.
2) Name four major parts of mitosis.
3) Identify important parts of a dividing cell.
The cell cycle has three major parts:
1.
2.
Interphase
Mitosis (Mitosis has four major sub-parts)
(Karyokinesis)
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
3.
Cytokinesis
Interphase
Nuclear envelope
Nucleolus
Characterized by:
1. Intact nuclear envelope
2. Visible nucleolus
3. Although you can’t tell it,
the cell’s DNA and other
cell components are undergoing
a process called replication
(duplication process);
chromosomes become doublestranded.
4. Three sub-phases: G1, S, and G2
Mitosis = Karyokinesis
Prophase
Condensed chromosomes
(chromatin fibers)
Characterized by:
1. Disappearing nuclear envelope
and nucleolus
2. Chromosomes (46* in each
human cell) coil and condense
*23 pairs of chromosomes
3. Spindle fibers (microtubules)
form and chromosomes become
attached by way of centromeres
4. Newly formed centrioles
move to opposite ends of the cell
Mitosis = Karyokinesis
Metaphase
Characterized by:
1. Chromosomes align across the
“equator” or metaphase plate
2. Centrioles stop at opposite
ends of the cell
3. Spindle apparatus is fully
formed
Spindle
apparatus
Centrioles
Metaphase plate
Centrioles
Mitosis = Karyokinesis
Anaphase
Centrioles
Centrioles
Shortening microtubules
(spindle fibers)
Characterized by:
1. Spindle fibers (microtubules)
shorten and separate the
chromosomes at the
metaphase plate
2. In the human cell, 46 singlestranded chromosomes move
in opposite directions toward
each pole
Can you name structures in the dividing cell?
single-stranded chromosome
centromere
centrioles
spindle fiber (microtubule)
Mitosis = Karyokinesis
Telophase
Characterized by:
1. Cleavage furrow forms
2. Nuclear envelopes begin to
form around two daughter
nuclei
3. Chromosomes decondense
4. Spindle disappears
cleavage furrow
daughter nuclei
Cytokinesis
(Division of cytoplasm and
contents into two cells)
This figure represents an overview of the cell cycle.