Unit 6 - The Cell Cycle

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Unit 6 - The Cell Cycle

• The white sections summarize key information and
  vocabulary terms are underlined.

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• Dreams
• I look to the sky and what do I see?A castle, a
  rainbow, and dreams for me,An end to this battle
  that I must fight,To rid my feelings of
  depression and fright,An end to cancer is not
  far away,It will be here someday... someday.
• Anonymous

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Observations
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What is the cell cycle?

• Much as your body goes through different stages
  in your life, the cells and viruses do too.
• The life cycle of the cell is known as the cell
  cycle.
• In this unit we will discuss the of the cell
  cycle (the process of making of new cells).

http//www.wadsworth.org/BMS/SCBlinks/mcewen/Media
/fig_1_cell_mitosis.jpg
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5 Reasons Cells Divide

• Growth- an organism will increase in size as the
  number of cells making up that organism increase
• Differentiation- cells develop specialized cells
  to carry out specific tasks
• ex the heart cell versus the muscle cell
• Repair- to repair lost or damaged cells
• ex mending of skin, blood vessels and bone
• Regeneration- ability to replace a lost limb or
  body part by rapid cell division ex starfish,
  lizard

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5 Reasons Cont.

• And finally
• Reproduction the making of a new organism

http//ghr.nlm.nih.gov/handbook/illustrations/mito
sismeiosisjsessionidB368026AB01E981849F2E31603F7
154F
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Cell Division

• The splitting of a single cell into two new
  daughter cells is called cell division.
• This will occur when a cell reaches its maximum
  size and the nucleus initiates cell division
  proteins called cyclins and enzymes begin this
  process.

http//protist.i.hosei.ac.jp/PDB/Images/Sarcodina/
Heliozoa/Actinosphaerium/cell_division_1.jpg
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Two Types of Cell Division

• Mitosis- the division of body cells (AKA somatic
  cells) due to the splitting of the nucleus to
  create two new cells.
• Meiosis the creation of gametes (AKA sex cells)
  by cutting the of chromosomes in half to create
  sex cells.

http//ghr.nlm.nih.gov/handbook/illustrations/mito
sismeiosisjsessionidB368026AB01E981849F2E31603F7
154F
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Chromosomes

• Review We have already learned that genetic
  information is held within the nucleus (of
  eukaryotes) in the form of DNA.
• Therefore, it is very important that cells must
  copy their genetic information before dividing.
• Cells tightly coil their DNA into chromosomes
  during the process of mitosis.

http//www.koshland-science-museum.org/exhibitdna/
images/dna/intro02.gif
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Chromosomes Cont.
http//www.learner.org/channel/courses/biology/ima
ges/archive/fullsize/1940_fs.jpg
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Chromosomes Cont.

• During mitosis, identical chromosomes pair up
  and are now called sister chromatids (1), held
  together by a centromere (2).
• Sketch it!

http//upload.wikimedia.org/wikipedia/en/5/54/Chro
mosome.png
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Stage 1 Interphase

• Interphase The period of growth for the cell
  before cell division (the longest stage) which is
  broken up into the following phases
• G1 growth and development organelles copied
• After G1 cells typically enter a resting phase,
  G0
• S synthesis phase copies of the DNA
• G2 more growth

http//dedunn.edublogs.org/files/2011/06/mitosis-2
6hzktr.jpg
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Knowledge Check
During the course of the life of a cell, there
is a complicated series of checkpoints to ensure
that everything is going according to plan. When
something happens to the genes for these
checkpoints, cancer can develop.
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Stage 2 Prophase

• Prophase The beginning of M phase mitosis DNA
  condenses and forms chromosomes
• Identical chromosomes (Xsomes) join
• Nucleus disappears

http//dedunn.edublogs.org/files/2011/06/mitosis-2
6hzktr.jpg

• Centrioles (the organelles which form the
  spindles) move to opposite poles
• Spindle fibers (long strings that help the cell
  divide) begin to grow

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Stage 3 Metaphase

• Metaphase Xsome pairs line up along the middle
  of the cell on the metaphase plate
• Centrioles have moved to the poles spindle
  fibers attach to Xsomes.

http//dedunn.edublogs.org/files/2011/06/mitosis-2
6hzktr.jpg
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Metaphase Cont.
http//student.ccbcmd.edu/courses/bio141/lecguide/
unit6/genetics/DNA/DNArep/images/metaphase1_pc.jpg

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Stage 4 Anaphase
http//dedunn.edublogs.org/files/2011/06/mitosis-2
6hzktr.jpg

• Anaphase The centromeres divide and spindle
  fibers pull the chromosomes apart from their
  partners
• The chromatids move to opposite poles of the cell

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Stage 5 Telophase

• Telophase The nuclei reform at each end of the
  cell
• Chromosomes uncoil into chromatin (or loose
  genetic material)
• Spindles release Xsomes and shorten.
• The cell begins to pinch as the cytoplasm begins
  to divide

http//dedunn.edublogs.org/files/2011/06/mitosis-2
6hzktr.jpg
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Stage 6 Cytokinesis

• Cytokinesis The final stage in M phase that
  divides the cell cytoplasm
• In animals, the cell membrane is drawn inward
  (cleavage furrow).
• In plants, a cell plate is built to create new
  cells walls and membranes.
• Each half has one nucleus and gets own set of
  centrioles ( organelles)
• The cell is now two and enters Interphase (G1).
• Animation

http//alevelnotes.com/content_images/i77_dwa_1_mi
tosis.gif
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Cytokinesis Cont.

• During mitosis, after all the genetic material
  is sorted out, the cell splits all of its
  cytoplasmic goodies in two and sends them to
  opposite ends. It then constricts in the middle
  and eventually pinches in half, producing two
  daughter cells. The location at which the
  pinching in occurs is known as the cleavage
  furrow. Image

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Visualizing Mitosis
Anaphase
Prophase
Telophase
Interphase
Metaphase
http//wiki.district87.org/images/9/9f/Plant_cells
.jpg
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Ex Mnemonics

• Example
• I I
• P please
• M make
• A another
• T two
• C cells!

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• Student Created Example
• I Intelligent
• P people
• M make
• A all
• T the
• C cash!

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http//buffonescience9.wikispaces.com/file/view/Mi
tosis-Animation-1.gif/294684052/236x228/Mitosis-An
imation-1.gif