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Cell cycle
 An ordered sequence of events in the life of a cell , from its origin
in the division of a parent cell until its own division into two. The
Eukaryotic cell cycle is composed of interphase (including G1, S1,
and G2 subphases) and M phase (including mitosis and
cytokinesis)
Mitosis
INTERPHASE
 A process of nuclear division in
eukaryotic cells conventionally divided
into five stages: prophase, prometaphase,
metaphase, anaphase, telophase. Mitosis
conserves chromosomes number by
allocating replicated chromosomes
equally to each of the daughter cells.
G1
S
(DNA synthesis)
G2
Cell cycle
A. Interphase: During interphase, cellular metabolic activity is high,
chromosomes and organelles are duplicated, and cell size may
increase.
B. Mitotic phase: cell is divided into two daughter cells.
1. Mitosis: nuclear division.
a. Prophase
INTERPHASE
b. Prometaphase
c. Metaphase
d. Anaphase
e. Telophase
2. Cytokinesis: division of cytoplasm.
G1
S
(DNA synthesis)
G2
Mitosis in an Animal Cell
Fragments
of nuclear
Chromosomes
Aster
Centrosomes
envelope Kinetochore
(duplicated,
(with centriole pairs)
Early mitotic
uncondensed) spindle
Nonkinetochore
Centromere
microtubules
Nucleolus Nuclear Plasma
envelope membrane
G2 of Interphase
Prophase
•A nuclear envelope encloses
the nucleus. The nucleus
contains one or more nucleoli.
•Two centrosomes have formed
by replication of single
centrosome.
•Chromosomes, duplicated
during S phase, cannot be seen
individually because they have
not yet condensed.
Centrosome at
one spindle pole
Metaphase
•The centrosomes are now
opposite poles of the cell.
•The chromosomes have all
arrived at the metaphase
plate. The chromosomes’
centromeres lie at the
metaphase plate.
Prometaphase
•The chromosomes become •The nuclear envelope
fragments.
more tightly coiled,
condensing into discrete
•The chromosomes have
chromosomes observable
become even more
with a light microscope.
condensed.
•The nucleoli disappear.
•Some of microtubules attach
• The mitotic spindle begins to the kinetochores,
becoming “ kinetochore
to form.
microtubules”, which jerk the
•The centrosomes move
chromosomes back and forth.
away from each other.
Metaphase plate(an imaginary plane)
Spindle
Kinetochore
microtubule
Chromosome, consisting
of two sister chromatids
Cleavage furrow
Daughter
chromosomes
Nucleolus
forming
Nuclear
envelope
forming
Anaphase
Telophase
•Anaphase begins when the
centromere are cleaved.
•The two daughter
chromosomes begin moving
toward opposite ends of the
cell as their kinetochore
microtubules shorten.
•Two daughter nuclei form in
the cell.
•Nucleoli reappear.
•The Chromosomes become
less condensed.
Cytokinesis
•The formation of a cleavage
furrow, which pinches the
cell in two.
1. 白魚囊胚細胞的有絲分裂
-- Whitefish, Mitosis
Interphase
Prometaphase
Metaphase
Anaphase
Telophase &
Cytokinesis
Prophase
Cleavage furrow
Mitosis in a Plant Cell
Nucleus
Chromatin
Nucleolus condensing
Prophase
•The chromosomes are
condensing and the
nucleolus is beginning to
disappear.
•The mitotic spindle is
starting to form. Although
not yet visible in the
micrograph,
Chromosomes
Prometaphase
•Discrete chromosomes are
now visible.
•The nuclear envelope will
fragment.
Metaphase
•The spindle is complete.
•The chromosomes have all
arrived at the metaphase
plate.
細胞板
Cell plate
Anaphase
• The chromatids of each
chromosome have
separated, and the
daughter chromosomes
are moving to the ends of
the cell.
Telophase
• Daughter nuclei are forming.
• Nucleoli reappear.
• The Chromosomes become
less condensed.
Cytokinesis
• The cell plate will divide the
cytoplasm in two.
2. 洋蔥根尖細胞的有絲分裂
-- Onion root, Mitosis
Prometaphase
Metaphase Prophase Interphase
Interphase
Telophase ＆
Cytokinesis
Prophase
Cell Plate
Anaphase
Telophase ＆
Cytokinesis
The content of report
1. Select a slide of onion cells or whitefish cells to record
observations. Draw the observed images, including interphase,
prophase, metaphase, anaphase, telophase & cytokinesis, and
describe the characteristics of the observed.
2. Question:
Description the differences of plant cells and animal cells
in mitosis?