Transcript chapter_1.3_presentation

Observing
Cells
Warm-up
 Answer
the following 3 questions on a
sheet of paper:
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Why are cells so small? (This was discussed
in the video from yesterday)
What are the two major kinds of cells? (Hint:
plant cells and animal cells are in the same
category)
What is the most easily identifiable part of a
cell?
Why are cells so small?
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The explanation of why cells do not grow very
large can be found in how cells function.
To carry out their work, cells need a constant
supply of materials such as oxygen, water,
and food particles. They also need to get rid
of waste products.
A larger cell would need more materials and
would produce more waste products.
Sizes and Shapes
 Cells
come in a variety of shapes and
sizes. Most cells, however, fall into a
narrow range of size- the “sweet spot” in
which they function most effectively.
 To grow bigger, organisms add more cells
to their bodies instead of growing bigger
cells.
Size and Shape
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We’ve learned that cells can’t be very big
because they need to bring in food and get
rid of waste through the cell membrane.
Think of it this way:
–
Imagine a cell as a swimming pool with a
diameter of 50 meters. To keep this “cell” alive,
you must swim to the center of the pool carrying
a beach ball (food), then swim back to the side
carrying a life buoy (waste).Imagine you have
to do this 12 times within a short span of time.
What difference would it make it the pool had a
diameter of 100 meters, and not 50?
Assignment 1
 Colour
the plant cell according to the
directions on the sheet, and answer the
questions at the bottom of the page.
 The assignment is due at the end of class
today. Don’t forget to write your name on
your paper!