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Mitosis
A Form of Cell Division
"Every cell comes from a
cell..." (R. Virchow)
I. Cell Size
A. Cells grow until they are too big to
take in sufficient nutrients or get rid
of wastes.
B. The cell will maintain itself or will
divide into two smaller cells.
C. The process of cell growth and cell
division is called the cell cycle.
The Cell
• The eukaryotic cell has a nucleus in which
there chromosomes.
• The chromosomes carry genetic
information in the form of DNA.
• During growth and maintenance the
chromosomes are spread out in the
nucleus in a
form called
chromatin.
Check Point
• 1. What is the process of cell growth and
division called?
– The cell cycle
• 2. Cell theory states that all living cells
come form___________.
– Existing cells
• 3. What carries genetic information in the
form of DNA?
– Chromosomes
II. Interphase
A. Most of the life of the cell is spent in
Interphase, a period of growth and
maintenance.
B. If the cell is a type that divides, then
it will go through a process of cell
division called mitosis.
Interphase
Check point
• What two main things happen during
interphase?
– Growth and DNA replication
III. Why Divide?
A. Single-celled organisms divide to
reproduce.
B. Cell division in multicellular organisms
enables the organism to grow larger
while the cells remain small.
C. A large surface:volume ratio is due to
small cell size. This allows sufficient
food to enter, wastes to leave, and
gases to be exchanged.
IV. What is Mitosis?
A. Mitosis is the division of the mature
parent (mother) cell into two smaller
daughter cells.
B. The daughter cells are identical to
the parent cell.
C. There are four stages called
prophase, metaphase, anaphase, and
telophase.
Check Point
• How many daughter cells does mitosis
produce?
V. Which Cells Divide?
A. Cells that divide constantly and
rapidly in animals:
1. Skin cells
2. Sperm cells
3. Bone marrow cells
B. Cells that divide constantly and
rapidly in plants:
1. Root tip cells
2. Phloem cells
3. Meristematic tissue for growth
and replacement
VI. Mitosis
A. Cells divide to make more cells.
B. While all the other organelles can be
randomly separated into the daughter
cells, the chromosomes must be
precisely divided so that each daughter
cell gets exactly the same DNA.
Maintaining cell identity
• Human body cells have 46 chromosomes, 23
from each parent.
• Every body cell has the same 46 chromosomes
• Each species has a characteristic number of
chromosomes: corn has 20, house flies have 10,
chimpanzees have 48.
• After cell division (mitosis), the resulting
daughter cells must have the same number of
chromosomes as the parent cell.
Chromosomes
• The essential part of
a chromosome is a
single very long
strand of DNA. This
DNA contains all the
genetic information
for creating and
running the organism.
VII. The Steps of Mitosis
A. In the parent cell the DNA in the
chromosomes is copied during
Interphase.
B. The four phases of mitosis divide
these copied chromosomes so that
each daughter cell will receive one
full set of the chromosomes.
Check point
• How many chromosomes do we get from
each parent?
– 23
Mitosis in Plant Cells
Prophase
Metaphase
Anaphase
Telophase
Mitosis in Animal Cells
Prophase
Metaphase
Anaphase
Telophase
Class Activity