Are there limits to cell size?

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Are there limits to cell size?
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Demonstration Recap

• Using 3 different sized agar blocks to represent
  cells (3 cm, 2 cm, and 1 cm), we observed the
  nutrient uptake of each when placed in
  solution.
• Although the nutrients traveled into the cells
  at the same speed, the cell that appeared to
  receive the most nourishment was the smallest
  one. This can be explained by the distance a
  particle from outside the cell would need to
  travel inwards to reach the center. In the small
  cell, this distance is the smallest.

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Data Surface Areas Volumes
Surface Area (6 x w x l) Volume (w x l x h) Surface Area Volume
1 cm Cube 6 x 1 x 1 6 1 x 1 x 1 1 6/1 6
2 cm Cube 6 x 2 x 2 24 2 x 2 x 2 8 24/8 3/1 3
3 cm Cube 6 x 3 x 3 54 3 x 3 x 3 27 54/27 2/1 2
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Data Observations

• 1 cm Cube
• (SA/V 6)
• 2 cm Cube
• (SA/V 3)
• 3 cm Cube
• (SA/V 2)

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Which cell was most efficient?

• This is the cell in which the nutrients (pink)
  got closest to reaching the core of the cell.
• Answer the smallest cell
• Based on this answer, can you tell me

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What is the relationship between cell size and
the rate at which nutrients reach the core of the
cell?

• The cell that received the most nutrition for
  all of its organelles was the smallest cell.
• It has a surface area to volume ratio of 6 to 1,
  which is the highest of all three cells. This
  means more of the cell was able to receive
  nutrients because it was directly exposed to the
  nutrient solution. The part of the cell that was
  not exposed did not receive nutrients until they
  traveled into the area. However, since the cell
  took up very little space (has a very small
  volume), the nutrients did not have far to travel
  once they got inside the cell.

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Does a cell have to be round?

• No, any shape is possible- however, the ratio of
  Surface Area to Volume may vary.

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What is the best shape and size for a cell?

• The best shape and size for a cell is one where
  the ratio of surface area to volume is high
  enough that the cell gets complete nourishment
  with minimal harm inflicted on itself in the
  process.
• HUH?! What?

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For instance

• IF you had a cell with a very small SA/V ratio
  (volume is very large), your cell might be so big
  that nutrients cannot reach their destination in
  time, and the cell will die.

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But on the other hand

• IF you have a cell with a very large SA/V ratio
  (surface area is very large), your cell will
  become very fragile and thin. It could die
  easily from heat exposure or snags.

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The best cell shape

• Would probably be a cell that is long and thin,
  tube-like.
• Good examples nerve cells, muscle cells, xylem
  and phloem cells in plants.

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Biggest Smallest Cells

• How big is the biggest cell?
• The biggest cell is an ostrich egg (about the
  size of a football).
• What are the smallest cells?
• Bacteria- Ever wonder why bacteria can produce a
  new generation in 20 30 minutes? And over ten
  million cells in less than a day?