giant amoeba eats new york city
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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. - PowerPoint PPT PresentationTRANSCRIPT
GIANT AMOEBA EATS NEW YORK CITYSurface-to-Volume Ratios and the Benefits of Being Multicellular
PREDICTIONSWhy do you think cells are so
small?
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GIANT AMOEBA EATS
NEW YORK CITYYou 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
SURFACE-TO-VOLUME RATIOA 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
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
SURFACE-TO-VOLUME RATIO
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
MANY KINDS OF CELLSMulticellular 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.
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
21
2
22
28 248 8
Cell A 28:8
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?