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Giant Amoeba Eats New York City

Giant Amoeba Eats New York City. Surface-to-Volume Ratios and the Benefits of Being Multicellular. Predictions. Why do you think cells are so small? ________________________________ ________________________________ ________________________________. Giant Amoeba eats New Y ork C ity.

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Giant Amoeba Eats New York City

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  1. Giant Amoeba Eats New York City Surface-to-Volume Ratios and the Benefits of Being Multicellular

  2. Predictions • Why do you think cells are so small? • ________________________________ • ________________________________ • ________________________________

  3. Giant Amoeba eats New York City • You will likely never see that headline • As cells get larger, they need more food and produce more waste • Therefore, more materials must be able to move in and out of the cell through the cell membrane

  4. Surface-to-Volume Ratio • A growing cell needs larger surface area through which to exchange materials • As cell’s volume increases, its outer surface grows too. But the volume increases at a faster rate than the surface area. So if a cell gets too large, it won’t have enough openings to allow materials in and out

  5. Why aren’t the Rates the Same? • Because Surface-to-Volume is actually a ratio • The Surface-to-Volume ratio decreases as cell size increases • Increasing the number of cells but not the size keep a high surface-to-volume ratio

  6. Surface-to-Volume Ratio

  7. Benefits of Being Multicellular • A single cell as big as your are would have an incredibly small surface-to-volume ratio. The cell would not survive because its outer surface would be too small to allow in the materials it would need • Remember, multicellular organisms grow by? • Why is an elephant larger than a human being? Producing more cells It has more cells, not larger cells

  8. Many Kinds of Cells • Multicellular organisms are able to do lots of other things besides grow • This is because different cells are specialized to do different jobs • Humans for example have specialized cells like muscle, eye, and brain cells which let us walk, run, watch a movie, think, and so on.

  9. Math Break • The shape of a cell can affect its surface-to-volume ratio. Examine the cells below and answer the questions that follow • What is the surface area of Cell A? Cell B? • What is the volume of Cell A? Cell B? • Which of the two cells has the greater surface-to-volume ratio? A B 4 2 2 2 1 2 28 24 8 8 Cell A 28:8

  10. Your Pet Paramecium • Imagine you have a pet Paramecium, a type of unicellular organism. The dimensions of your Paramecium are 125 m x 50 x 20. If 7 food molecules can enter through each square micrometer of surface every minute, how many molecules can it eat in 1 minute? • If your pet needs 1 food molecule per cubic micrometer of volume every minute to survive, how much would you have to feed it every minute?

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