Transcript Mitosis - White Plains Public Schools

Mitosis
The Process of Cellular Asexual
Reproduction
Asexual Reproduction
• Asexual reproduction occurs
when there is only one
parent or parent cell.
– Mitosis (cell division)
– Binary Fission (bacteria
and protist division)
– Budding (yeast and hydra)
– Spore formation (mold
and fungus)
– Regeneration (regrowth of
lost body part)
– Vegetative Reproduction
(bulbs, tubers, runners,
rhizomes and grafting)
The Cell Cycle
• Mitosis: cell
divides
• Interphase
consists of G1, S
and G2
• G1: growth,
synthesis of
proteins and
organelles
• S: chromosomes
are replicated,
DNA synthesis
• G2: preparation
for mitosis
Parts of a Chromosome
• During interphase the
DNA is replicated.
• During mitosis the DNA
condenses into visible
structures called
chromosomes.
• Each chromosome
consists of two identical
“chromatids”
• The centromere
connects the two
chromatids.
Prophase
• Structures called
centrioles appear and
move to opposite sides
of the cell
• Fibers begin to
connect each centriole
to the centromere of
each chromosome
• Nuclear membrane
disappears
Centrioles
Spindle Fibers
Metaphase
• Fibers now connect
the centromeres of
each chromosome to
the centrioles at each
side of the cell
• The chromosomes
line up along the
middle of the cell
Anaphase
• The centromeres
connecting each pair
of chromatids
separate.
• The fibers pull the
chromosomes apart
to opposite sides of
the cell
Telophase
• Fibers separate from
the chromosomes
• Chromosomes
unravel
• A nuclear membrane
forms around each
new set of
chromosomes
Cytokinesis
• Cell membrane
pinches together
separating the
cytoplasm and
organelles into two
new individual
daughter cells.
Mitosis and Chromosome Number
• A human skin cell has 46 chromosomes
• At the end of mitosis each daughter cell has
46 chromosomes
• Why is mitosis an example of asexual
reproduction?