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Cell Reproduction


Prokaryotes
Bacteria
Eukaryotes
Plants & animals
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Prokaryotes
 Lack
a nucleus
 Have a single chromosome
 Reproduce by binary fission
 Include bacteria
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Steps in Binary Fission




Used by bacteria
Cells increase their
cell mass slightly
DNA & cell
components are
replicated
Each cell divides into
2 daughter cells
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Binary Fission of Bacterial Cell
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E. Coli Dividing by Binary
Fission
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Eukaryotes
 Contain
a nucleus &
membrane bound organelles
 Asexually reproduce cells by
mitosis
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Cell Cycle






Stages in growth &
division
G1 Phase
S Phase
G2 Phase
M Phase
Cytokinesis
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G1 Phase
 First
growth stage
 Cell increases in size
 Cell prepares to copy its
DNA
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Synthesis Phase
 Copying
of all of DNA’s
instructions
 Chromosomes duplicated
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G2 Phase
 Time
between DNA synthesis
& mitosis
 Cell continues growing
 Needed proteins produced
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M Phase
 Cell
growth & protein
production stop
 Cell’s energy used to make 2
daughter cells
 Called mitosis or
karyokinesis (nuclear
division)
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Life Cycle of a Cell
Mitosis is a cycle with no beginning or end.
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Interphase – Resting Stage
 Cells
carrying on normal
activities
 Chromosomes aren’t visible
 Cell metabolism is occurring
 Occurs before mitosis
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Interphase
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Stages of Mitosis
 Prophase
 Metaphase
 Anaphase
 Telophase
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Cells Undergoing Mitosis
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Steps in Prophase
 DNA coils
tightly & becomes visible
as chromosomes
 Nuclear membrane disappears
 Nuceolus disappears
 Centrioles migrate to poles
 Spindle begins to form
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Prophase
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Eukaryotic Chromosome
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Human Chromosomes
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Steps in Metaphase
 Spindle
fibers from centrioles
attach to each chromosome
 Cell preparing to separate its
chromosomes
 Cell aligns its chromosomes in
the middle of the cell
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Metaphase
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Steps in Anaphase
 Cell chromosomes are
separated
 Spindle fibers shorten so
chromosomes pulled to ends of
cell
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Mitotic Spindle
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Anaphase
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Steps in Telophase
 Separation
of chromosomes
completed
 Cell Plate forms (plants)
 Cleavage furrow forms(animals)
 Nucleus & nucleolus reform
 Chromosomes uncoil
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Telophase
Plant
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Animal
Cytokinesis
 Occurs
after chromosomes
separate
 Forms two, identical
daughter cells
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Cytokinesis
Cell Plate Forming in Plant Cells
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Prophase
Spindle
forming
(PREPARE)
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Metaphase
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
(MIDDLE)
Anaphase
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
(AWAY)
Metaphase
Telophase
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Individual
chromosomes
Anaphase
(TWO)
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Metaphase
Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
(TWO IDENTICAL DAUGHTER CELLS)
Metaphase
Let’s Review…
IV. Cell Specialization
A. Cells in Unicellular
Organisms…
1. One cell makes up entire organisms.
• No cell specialization.
B. Cells in Multicellular
Organisms…
1. Cell Specialization
• All of an organism’s cells have the same DNA
• Different cells use different genes to perform different functions
• Why do prokaryotes NOT have cell specialization?
Cells in Multicellular
Organisms…
• Cell Specialization Examples:
• Blood cells carry oxygen
• Muscle cells control movement
• Nerve cells used for response