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Sam’S PuPPy
• Body cell reproduction involves producing
new daughter cells for growth of tissues as
well as repair and replacement of old cells.
• Most living body cells eventually divide
into two cells through a process called
mitosis. This can happen because food and
nutrients are broken down and become
building blocks for new living materials like
the new cells produced during cell
division.
LT #5 I can DESCRIBE how cells multiply.
Why do cells divide?
• Weeds can grow pretty fast. In fact,
the stems and roots of a fastgrowing plant seem to get longer
over night. Where do the new stem
and root parts come from?
– They are made when existing cells
divide to form new cells. This process
is called cell division.
Why do cells divide?
• Eventually cells need to duplicate.
There are two types of cell
division, mitosis (growth) and
meiosis (reproduction).
• Mitosis allows organisms to grow
larger, and also helps organisms
replace injured cells. GROWTH!
Mitosis
• The big idea to remember is that
mitosis is the simple duplication of a
cell and all of its parts.
• It duplicates its DNA and the two new
cells (daughter cells: cells resulting from
the replication and division of a single
parent cell) have the same pieces and
genetic code.
Two identical copies come from one
original. Start with one; get two that
are the same. Get the idea?
Mitosis
• Before a eukaryotic cell (a cell with
an organized nucleus) divides, the
genetic material in the nucleus of
the cell copies itself.
• When the cell divides, the nuclear
material splits in half so that each
daughter cell gets genetic material
that is the same as that of the
parent cell.
Mitosis
• The dividing of the nuclear
material is known as mitosis.
• In the last stage of cell division,
the cytoplasm divides as well.
• There are now two complete
cells where there used to be
one.
Science Alert!
• The terms mitosis and cell division
are sometimes used
interchangeably.
• BUT…mitosis really refers only to
the dividing of the nuclear material.
• While…cell division is the complete
process of copying and dividing the
whole cell.
Cell Division Phases
• Beyond the idea that two identical
cells are created, there are
predictable stages or phases in the
cell division process.
• These steps ensure that the new
daughter cells are the same as the
cell from which they formed.
Cell Division
• There are 5 basic phases in the lifecycle of a cell.
–Interphase
–Prophase
–Metaphase
–Anaphase
–Telophase
Cell Division
• The following mnemonic devices can
help you remember the phases of cell
division.
• I prefer milk and tea.
• I propose meeting at ten.
• In Poland men are tall.
• CAN YOU COME UP WITH YOUR OWN
mnemonic device?
Cell Division/Mitosis
• Interphase
– The stage before cell division starts.
– As a cell prepares to divide, each
chromosome in the nucleus makes an
exact copy of itself.
– Chromosomes: a structure made of DNA that
contains the genetic info used to direct cell activity
and make new cells
Cell Division/Mitosis
• Prophase
– The nucleus prepares for cell division.
– The genetic material shortens and
thickens.
– The chromosome copies are held
together at their centers, so they form a
sort of “X.”
Cell Division/Mitosis
• Metaphase
– The two copies of each chromosome
line up in the center of the cell.
Cell Division/Mitosis
• Anaphase
– The copies separate.
– One complete set of chromosomes is
pulled to one side of the cell.
– The other complete set is pulled to the
other side of the cell.
Cell Division
• Telophase
– Final stage of cell division
– The cytoplasm pinches in at the
center of the cell, dividing the cell in
half.
– When cell division is complete, two
new daughter cells are formed.
– The daughter cells are identical to
the parent cell.
Two identical copies come from one
original. Start with one; get two that
are the same. Get the idea?
Mitosis Rap
Time!