Download Why are cells small?

Why are cells small?
Think about this……
Now that you’ve thought about
it…
 Turn
to the person next to you and in 20
seconds (I’ll say “start” and “stop”) come
up with one, specific reason cells have to
be small.
Surface Area
 The
surface
around the cell,
the cell
membrane’s size.
Volume
 The
contents of
the cell, what’s
inside.
 The
 The
 surface
 volume=space
amount of cell
membrane
area=around
amount of
cytoplasm
taken up
Cell Size
As cell size
increases, the
surface area to
volume ratio
decreases.
o Rates of chemical
exchange may
then be
inadequate for cell
size.
o Cell size, therefore,
remains small.
o
Calculating surface area to volume ratios
Surface area = (length x width) (number of sides)
Volume = length x width x height
Surface area : volume = ratio
The larger the surface area to volume ratio
number gets, the harder for the cell to perform
movement of materials.
Quick check
Think about these, form answers SILENTLY
and be ready, you may be chosen to
answer!
A) As a cell gets larger (grows) what
happens to the cell’s surface area?
B) As the cell gets larger (grows) what
happens to the cell’s volume?
C) Which one increases faster?
D) Why is this a problem?