Cell Growth and Reproduction

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Cell Growth and Reproduction

• Cell Theory
• All cells come from pre-existing cells.
• Body Cell Division Mitosis
• Cells produced from one cell (parent cell).
• Result is two or more identical cells.
• Repairs worn-out tissue. (ex skin)
• Allows organisms to grow and change.
• Ivy to wrap around a trellis

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From birth to rebirth, a cell progresses through
stages that make up the Cell Cycle.

• Interphase -regular cell activities and growth
• Mitosis-cell division is just a short stage in
  in
• a cells life.

Progress through the cell cycle is carefully
regulated.
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Cell Cycle
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Cell Growth and Reproduction

• Cell Cycle Sequence of growth and division of
  the cell.
• Majority of cells life is spent during
  INTERPHASE or the cells growth period

Interphase
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Cell Growth and Reproduction

• INTERPHASE
• Longest phase Growth Phase
• Cell grows in size
• Carries on metabolism
• Chromosomes are duplicated to prepare for
  division
• 3 Stages

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Cell Growth and Reproduction

• INTERPHASE
• 3 Stages
• Cell grows, protein production is high
• Cell copies its chromosomes
• Centrioles replicate and cell prepares for
  division

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Interphase -main part of the Cell Cycle.

• Chromatin (long thin DNA molecule) is stored in
  the nucleus and it controls the cell activities
  and its overall design and function.
• Longest part of the cell cycle.

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DNA
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Replication copying of DNA during Interphase
Synthesis phase.
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Cell Growth and Reproduction

• Chromatin long strands of DNA wrapped around
  proteins
• Chromosomes exist as chromatin for most of cells
  lifetime
• Spaghetti noodles
• Chromosomes carry genetic information that is
  copied and passed on to new cells
• Like wound spaghetti

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Cell Growth and Reproduction
Chromosome
Chromatin
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Cell Growth and Reproduction

• Before cell division, chromosome is
• in spaghetti-like CHROMATIN state
• As cell division begins, chromosomes take on a
  new tightly packed shape
• Why do you think this is important?

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Cell Growth and Reproduction

• After INTERPHASE, cell enters period of division,
  also called MITOSIS
• Mitosis period of cell division
• As cell gets to the maximum size, it begins to
  undergo MITOSIS (cell division)
• Forms two daughter cells with complete set of
  chromosomes.

Mitosis
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Mitosis results in the production of two cells
that are genetically identical to the original
cell.
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Mitosis has four phases/stages PMAT

• Prophase
• Metaphase
• Anaphase
• Telophase

P
A
M
T
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Mitosis
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Cell Growth and Reproduction

• 1st Phase of Mitosis PROPHASE
• Long stringy chromatin coils up into visible
  chromosomes

Spindle fibers
Disappearing nuclear envelope
Doubled chromosome
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Mitosis begins with the phase PROPHASE

• Centrioles form spindle and
• Chromatin (DNA) condenses into paired chromosomes.

Sister chromatids
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Mitosis second stage isMetaphase!

• The nuclear membrane dissolves.
• The centrioles move to opposite ends while
  forming the spindle.
• The chromosomes line up in the middle of the cell.

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Microtubules

• Microtubules are small cylindrical fibers that
  change in length by assembling (polymerizing) and
  disassembling (depolymerizing).
• They are made of a protein called tubulin.
  Tubulin dimers are arranged to form a long hollow
  cylinder.
• The fibers are lengthened and shortened as
  tubulin dimers assemble or disassemble from one
  or both ends of the filament.
• The assembly of microtubules is controlled by an
  area near the nucleus called the centrosome or
  microtubule organizing area..
• Microtubules act as tracts along which organelles
  can move. For example, they are associated with
  movement of vesicles from the Golgi complex to
  the plasma membrane.
• Microtubules are responsible for the movement of
  cilia and flagella.
• They move the chromosomes during cell division in
  the spindle apparatus.

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Mitosis third stage isAnaphase!

• The chromatids (daughter chromosomes) are pulled
  apart
• by the spindle and move to opposite ends of
  the cell.

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Anaphase Chromatids are pulled apart
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Mitosis Cell Division

• 3 TELOPHASE
• The nucleus forms around each identical set of
  chomosomes.
• The spindle disappears.
• Share the same cytoplasm.

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Telophase The newly divided animal cell pinches
itself off in the middle a plant cell forms a
cell plate.
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Cell Growth and Reproduction

• CYTOKINESIS
• The two identical (daughter) cells completely
  separate and no longer share a membrane.
• DNA forms into chromatin again.

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Cytokinesis in Plants is different than Animals
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What is the longest phase of the cell cycle?
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MitosisPMAT
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Control of the Cell Cycle

• What happens when MITOSIS goes WILD?
• CANCER

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Control of the Cell Cycle

• Cancer
• Malignant growth due to uncontrolled cell
  division.
• Genetic changes to genes that control cell
  growth.
• Caused by environmental and genetic factors.

                                                
                                                  
                          Lung cancer cells
(530x). These cells are from a tumor located in
the alveolus (air sac) of a lung.
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Control of the Cell Cycle

• Cancerous cells form masses of tissues called
  MALIGNANT tumors.
• Tumors starve normal cells from nutrients
• Wait! But cant I have a BENIGN tumor?
• YES! Benign tumors are masses of tissues that
  are harmless. (BENIGN HARMLESS)
• Created by slower growing cells that clump
  together to form lumps.

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Control of the Cell Cycle

• Cancer METASTASIS
• In later stages, cancer spreads, enters
  circulatory system, and spreads throughout body.
• Forms new tumors that disrupt functions of
  organs, organ systems, and organism as a whole.

Skin cancer cells with a dividing cell stained
red.
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