Eukaryotic Cell Division
Purpose
Increase cell number for growth, maintenance,
repair, or reproduction
Cell Types
Somatic
Germ
Cell Division Cycle
Interphase
Nuclear Division (Mitosis or Meiosis)
Cytokinesis
Fig. 5.1a
TERMINOLOGY
Genetic Material
Structural Types
Chromatin
Uncoiled genetic material not visible
with a light microscope.
Chromosome
Coiled genetic material visible with a
light microscope.
Fig. 5A
TERMINOLOGY
Genetic Material
Structural Apparatus
Sister Chromatids
One of two identical copies of genetic
material attached at the centromere.
Centromere
Constricted portion of a chromosome that
holds sister chromatids together.
Kinetochore
Protein structure at the centromere to which
spindle fibers attach.
TERMINOLOGY
Centrioles
Cylindrical structure within a centrosome
producing spindle fibers.
TERMINOLOGY
Mitotic Spindles (Spindle Fibers)
Microtubules that bring about chromosomal
movement.
SOMATIC CELL DIVISION
Somatic Cells
Definition
All diploid cells that are not involved in
gamete formation.
Examples
Skin, Heart, Liver, Intestinal, Bone, Muscle
Type of Cell Division
Mitotic (Mitosis)
Steps
Interphase
Mitosis
Cytokinesis
SOMATIC CELL DIVISION
Mitotic Cell Division
Outcome
Each daughter cell is a clone of the parent.
Each cell has homologous pairs (diploid,
2N) of chromosomes.
Human Karyotype
46 chromosomes
. 22 paired autosomes
. 2 sex chromosomes ( XX or XY)
KARYOTYPE
Homologous Pairs, Diploid, 2N
Autosomes
#1-22
Sex
Chromosomes
Humanoid
Daughter’s Old Boyfriend
22.9
MITOTIC CELL DIVISION
Interphase
Purpose
Preparation for cell division.
Steps
G1 (Gap 1) Phase
S Phase (Synthesis)
G2 (Gap 2) Phase
Genetic Material
Chromatin
INTERPHASE
G1 (Gap 1) Phase
Undividing Cell
1) Cell growth
2) Cell metabolism
Dividing Cell
1) Organelles begin to replicate
2) Preparation for S phase
a) DNA is checked for damage
b) Environment is checked for adequacy
c) Cell size is checked
Fig. 5.1b
G1 PHASE
INTERPHASE
S (Synthesis) Phase
DNA replication
Formation of Sister Chromatids
DNA REPLICATION
Sister Chromatids
INTERPHASE
G2 (Gap 2) Phase
Final preparation for mitosis.
Check for DNA damage
Check to see that S phase is complete
Check the environment for adequacy
Finish Organelle Replication
Fig. 5.1b
MITOTIC CELL DIVISION
Mitosis
Purpose
Nuclear division
Separation of sister chromatids
Steps
Prophase
Metaphase
Anaphase
Telophase
MITOSIS
Prophase
1) Chromatin coils becoming chromosome.
2) Nuclear envelope disintegrates.
3) Centrioles produce mitotic spindles and
move toward the spindle poles
4) Kinetochore fibers attach to kinetochores
5) Polar fibers run from pole to pole
6) Asters attach centrioles to plasma
membrane
MITOSIS
Metaphase
Centriole movement aligns chromosomes at
the spindle equator.
M Checkpoint for spindle fiber attachment.
MITOSIS
Anaphase
1) Kinetochores pull on Kinetochore fibers
2) Sister chromatids separate.
a) Chromatids are now referred to as
“Daughter Chromosomes”.
3) Daughter chromosomes move toward
opposite spindle poles.
Daughter Chromosome
MITOSIS
Telophase
1) Chromosomes arrive at spindle poles.
2) Nuclear membrane regenerates.
3) Spindle fibers disintegrate.
4) Chromosomes become chromatin.
CYTOKINESIS
Purpose
Formation of two daughter cells.
Types
Animal Cell
Cleavage Furrow
Formation of a contractile ring at the cell
equator which will "pinch“ the cell in two.
Plant Cell
Cell Plate
Construction of a new cell wall inside of the
cell creating two cells.
ANIMAL CYTOKINESIS
ANIMAL CYTOKINESIS
DAUGHTER CELLS
PLANT CYTOKINESIS
PLANT CYTOKINESIS