Cell Growth

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Mitosis and Meiosis
Cell Growth and Division
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Eukaryotic Cell Division

• Stage 1 Mitosis
• Stage 2 Cytokinesis

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Interphase-(the long period)

• G1 Phase Cell grows, makes new proteins and
  organelles
• G0 Phase Cells hang out and perform usual
  functions
• S Phase DNA is replicated
• G2 Phase Organelles required for division are
  synthesized

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MITOSIS
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MITOSIS

• The shortest part of the cell cycle
• Lasts from a few minutes to several days

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MITOSIS

• Consists of 4 Phases
• -Prophase
• -Metaphase
• -Anaphase
• -Telophase

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Prophase

• Nuclear envelope dissolves
• Nucleolus disappears
• Chromosomes become visible
• Centrioles move to poles
• Spindle fibers form

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Metaphase

• Chromosomes line up at the equator (center)
• Spindles connect to the centromere of each
  chromosome

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Anaphase

• Centrioles split chromosomes into sister
  chromatids
• Phase ends once chromatids
  reach the poles

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Telophase

• Chromosomes uncoil
• A nuclear envelope surrounds DNA
• Nucleolus re-forms
• Spindle fibers break down
• Cell division is not complete!

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Cytokinesis

• Divides cytoplasm

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Cytokinesis continued
In plants, a cell plate forms between the 2 new
cells
Forms new cell wall!
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Let's Review!
Prophase
Anaphase
Watch this 1st!
Metaphase
Telophase
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Meiosis
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During sexual reproduction, gametes (sperm or
eggs) are produced by each parent
Dads chromosomes
Moms chromosomes
Gametes contain half the number of chromosomes
found in most cells
Dads gametes
Moms gametes
When gametes unite, the zygote then has the
normal number of chromosomes
zygote
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Diploid vs. Haploid
DIPLOID Contains BOTH sets of chromosomes (1
from each parent)
Normal cell
2N
HAPLOID Contains 1 set of chromosomes to combine
during sexual reproduction with another to form a
DIPLOID cell.
Gamete 1N
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Meiosis has 2 distinct phases
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1 Interphase 1
Normal cell (diploid)
replicates its DNA
forming sister chromatids
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2 Prophase 1
Chromosomes pair
into homologous chromosomes
forming a TETRAD
where crossing over occurs
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3 Metaphase 1
Homologues line up _at_ equator
completely randomly
spindle fibers attach
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4 Anaphase 1
Homologues are
pulled to poles
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5 Telophase 1 Cytokinesis
Nuclear Membranes form
cell separates
into haploids (1N)
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Meiosis has 2 distinct phases
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6 Prophase 2
No DNA replication
New centrioles form
Nuclear membrane dissolves
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7 Metaphase 2
Chromosomes line
up at the equator
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8 Anaphase 2
Paired chromatids separate
pulled to poles
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9 Telophase 2 and Cytokinesis
Gametes produced
Half the number of chromosomes