Chromosomes and Cell
Reproduction
Objectives:
1. Identify different types of cell division
2. Differentiate between a gene, a DNA
molecule, a chromosome, and a chromatid.
3. Be able to compare haploid and diploid cells
4. Predict how mutations at the chromosome
level can affect development.
About 2 trillions cells are produced
by an adult human body every day
What are some of the reasons why cells
need to divide in our bodies?
Why do cells reproduce
• For growth
• Repair
• And reproduction
There are Two Types
of Cell Division
Mitosis
Meiosis
•Makes new somatic cells
(body cells)
•Makes germ cells or
gametes ( egg and sperm)
• These cells are used for
Growth and Repair of
tissues
• These cells are used for
reproduction
There are 5 stages of Mitosis
plus Cytokinesis
Interphase
Prophase
Metaphase
Anaphase
Telophase
and, Cytokinesis
Interphase
Cell grow and carries out if normal cell processes
DNA Replicates
Prophase
•
•
•
•
Nuclear membrane disintegrates
Nucleolus (nuclear membrane) disappears
Chromosomes condense
Mitotic spindle begins to form between the
poles
Spindle Apparatus
Includes
• Centrioles: Located at the poles of the cell,
and send out spindle fibers.
• Spindle fibers: attach to the centremere of
each sister chromatid, in order to pull
them
Centromere
apart.
↑
↑Spindle
The spindle apparatus ensure
that fiber
each new
Centrioles →
cell receives
1 full copy of the genetic
material
Metaphase
• Chromosomes attach to mitotic spindle
and align along the metaphase plate (the
equator of the cell).
Anaphase
• Microtubules shorten, moving chromosomes
to opposite poles
Telophase
•Chromosomes reach poles
of cell.
•Nuclear envelope re-forms.
•Nucleolus reappears.
•Chromosomes decondense.
Cytokinesis
Plant Cells
Cell plate forms dividing
daughter cells
Animal Cells
Cleavage furrow forms at
equator of cell and pinches
inward until cell divides in
two
Cleavage →
Furrow
The result is two
identical
daughter cells
That are Diploid
(having 2 copies of
each chromosome).