Download Mitosis

CELL CYCLE
The Cell Cycle
• Cells must divide to maintain maximum
efficiency.
• Mitosis is the process in which somatic
(body) cells divide to form a new cell.
• Mitosis consists of four phases.
• Interphase is the period in between each
mitotic cell division.
Reproduction
• Asexual Reproduction: A single cell or group of
cells each duplicates its genetic material and then
splits into two new genetically identical cells.
– The offspring are genetically identical
• Sexual Reproduction: Genetic material from each
of two parents combines, producing offspring that
differ genetically from either parent.
– Involves the union of sex cells (egg and sperm)
Parent
cell
DNA replicates
Cell division = One
cell makes two cells
Two daughter cells
are genetically
identical to each
other and to parent
cell = clones
The same DNA can appear in two forms
Chromatin = uncondensed DNA
Chromosome = condensed DNA
1 Chromosome
1 chromatid per chromosome
1 DNA double helix
DNA replication
1 Chromosome
2 chromatids per chromosome
2 DNA double helices
Cell division in eukaryotic cells:
Cytokinesis = division of the cytoplasm
Interphase
• Interphase is made of 3 stages.
• The Gap 1 and 2 or G1 and G2 phase is when
cells grow and make RNA, proteins, and other
macromolecules.
• The S or Synthesis phase is when the cell is
making DNA.
DNA Replication
• During the S phase of the cell cycle, DNA
replicates.
• A short section of the DNA uncoils.
• New nucleotides bond to the open sections of
the DNA.
• The “new” and “old” sections of DNA
separate and now there are 2 DNA strands.
Interphase
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ATP is synthesized.
Damaged parts are repaired.
Wastes are excreted.
Proteins are made.
Organelles are formed.
Chromosomes are copied.
Specialized tasks are performed .
Interphase
nucleus
DNA = Chromatin
Interphase
Chromatin
in nucleus
Mitosis
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Mitosis consists of four phases
Prophase
Metaphase
Anaphase
Telophase
Prophase
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Longest phase.
Chromatin coils.
Nucleus disappears.
Centrioles migrate.
Spindle forms.
Prophase
Nuclear membrane
disappears
Nucleolus disappears
Chromatin condenses into
chromosomes
Spindle fibers appear
Chromatin
Chromosomes
Metaphase
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Chromatids attach to spindle fibers.
Chromatids migrate to equator of spindle.
Metaphase
Chromosomes line up in center of cell
Centromere = holds chromatids together
Chromatids
(DNA double helix)
Two chromatids
per
chromosome
Anaphase
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Centromere splits.
Chromatids are separated.
Chromatids are now called chromosomes.
Anaphase =
Sister chromatids separate
from each other
Telophase
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Cytoplasm divides.
Nucleus reappears.
Chromosomes uncoil.
Telophase
Cytokinesis makes 2 new cells
Chromosomes decondense
into chromatin
Nucleolus reappears
Nuclear membrane reappears
Early Telophase
Late Telophase
Cytokinesis
• In the process called
cytokinesis, the cytoplasm
divides and two identical
daughter cells are formed.
Animal cell
membranes
pinches
together
between two
new cells
Cytokinesis
Plant cell
wall grows
between two
new cells
Interphase
Prophase
Prophase
Telophase
Metaphase
Telophase
Anaphase
Plant
Cytokinesis =
division of
cytoplasm
Telophase
Interphase
Anaphase
Prophase
Animal cytokinesis =
pinching of plasma
membrane
Early telophase
http://www.unm.edu/~asmund/mitosis.jpg
Metaphase
Late Telophase
Plant or
Animal cell
mitosis?
Plant