Mitosis and

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Mitosis and Asexual Reproduction
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• Cell Cycle

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Period of time from one division to the next
Unicellular division results in formation of new
individuals of the species
Cell Cycle
Multicellular division results in replacement of
old or damaged cells
Process by which the nucleus divides while
maintaining number of chromosomes
Mitosis
Division of the cytoplasm
Cytokinesis
Asexual Reproduction
Reproduction that only involves one parentso
therefore no special reproductive organsare
needed
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Nuclear DNA wound around proteins knownas
histones
Chromatin
Chromosomes
Condensed rolls of chromatin that are able to be
seen during mitosis (rod-like structures)
There are 4 phases in MITOSIS
Prophase
Metaphase
Anaphase
Telophase
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Interphase
Known as resting phase

• Interesting things happen
• Cells grow in size by producing more nucleic
  acids, proteins,and cellular organelles

• Chromosomes make copies of themselves, but they
  cant be seen

• Nucleus of the cell is contained within the
  nuclear envelope

• Centrioles are present and duplicate themselves

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Prophase

• Chromosomes Pair Up!
• Double chromosomes become visible - Chromatid

• Chromosomes are 2 sister chromatids connected by
  a centromere

One Double Chromosome
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• At the beginning, centrioles move to opposite
  poles

• Aster (star shaped fibers) extend microtubules

• Spindle fibers attach (to centromere to pull away
  chromatids toopposite sides of the cell)

• By the end, the nuclear envelope and nucleus have
  
• disappeared

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Metaphase

• Chromosomes Meet in the Middle!
• Centromeres line up on the equator (middle
  metaphase plate)

• By the end, the centromeres divide and pull the
  daughter chromosomes to opposite sides of the
  cell

• Half of each chromosome goes to the opposite side
  of the cell

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Anaphase

• Daughter chromosomes move to opposite sides of
  cell
• (poles)

• Chromosomes get pulled Apart!
• Movement is accomplished by the microtubules

• Movement occurs by shortening of the microtubules

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Telophase

• Now there are Two!
• Chromosomes uncoil and return to previous shape
  (threadlike)

• Nuclear membrane and nuclei reform

NOTE Cytokinesis begins during late anaphase and
finishes during telophase
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Mnemonic Device
An easy way to remember theorder of the phases
in mitosisis to think
PMAT PASSED MY ARITHMETIC TEST!!
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Mitosis in Plants
Same as mitosis in animals except

• Plants have no centrioles spindle fibers take
  their place

• Asters do not form

• Cell wall does not pinch because it is too rigid

• Cell plate divides the cell into two

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D. Protein that causes cells to go through cell
cycle is called cyclin
Asexual Reproduction
Occurs only through the process of mitosis

• Each offspring has the same genetic information

Where can asexual reproduction be found?
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There are 5 different types of asexual
reproduction.
1. Budding
Parent divides unequally new individuals develop
from buds ex yeast hydra
2. Binary Fission
Most simple form of asexual reproduction Parent
divides equally and results in two separate
individuals Ex.-paramecium
3. Spore Formation
Single specialized cells that germinate when
released from parent. Usually covered by a
protective coating for preservation.
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4. Regeneration/fragmentation
Ability to regrow new body parts/ability to grow
new Organism from parts. ex hyrda, planaria,
starfish
5. Vegetative Reproduction/Propagation
Refers to roots, stems, and leaves. Cells divide
then differentiate to produce the same
organism Ex.- strawberry plant, pick-a-back plant