Transcript Section 10.1

Section 10.1
Cell Growth
Book work review (Get your
highlighters ready!)
1. What are two reasons why cells divide
rather than continue to grow indefinitely?
a.
b.
More demands the cell places on its
DNA (DNA overload)
Cell has more trouble moving enough
nutrients and wastes across the cell
membrane
Book work review
2. Is the following sentence true or false? As
a cell increases in size, it usually makes
extra copies of its DNA.
False. How do we change the statement to
make it true?
Book work review
3. Circle the letter of what determines the
rate at which food and oxygen in a cell are
used up and waste products produced.
The cell’s volume.
Book work review
4. How can you obtain a cell’s ratio of
surface area to volume?
Divide the surface area by the volume.
Book work review
5. If a cell’s surface area is 6 cm2 and its
volume is 1 cm3, then what is its ratio of
surface area to volume?
6:1
Book work review
6. Is the following sentence true or false? As
a cell grows in size, its volume increases
much more rapidly than its surface area.
True
Book work review
7. Circle the letter of what happens to a
cell’s ratio of surface area to volume as the
cell’s volume increases more rapidly than its
surface area.
The ratio decreases.
Book work review
8. What is cell division?
The process by which a cell (parent) divides
into two new daughter cells.
Book work review
9. How does cell division solve the problem
of increasing size?
1.
2.
Before division, cell replicates (copies)
all DNA for the new daughter cell.
Reduces cell volume (increased ratio of
surface area to volume).
Cell 1 cm sides
Cell 3 cm sides
Surface area: 6 cm2
 Volume: 1 cm3


Surface area: 54 cm2
 Volume: 27 cm3
Surface Area and Volume
***Highlight/circle the surface area
equation and volume equation
1. 27 smaller cells x 6 cm2 = 162 cm2
2. 27 smaller cells greater surface area
Whiteboard review
Are the cells of a small plant larger or
smaller than those of a large plant?
Are the cells of a small animal larger or
smaller than those of a large animal?
The cells would be roughly the same size.
Size of the organism itself does not affect
cell size.
Whiteboard review
So, make a general statement that compares
the number and size of cells in small
organisms to those in larger organisms.
Small organisms have less cells than larger
organisms, but the cells are roughly the
same size no matter the size of the
organism itself.
Whiteboard review
What are the reasons (2) that cells stay
small?
1.
2.
More demands the cell places on its
DNA (DNA overload)
Cell has more trouble moving enough
nutrients and wastes across the cell
membrane
Whiteboard review
The rate at which food/waste exchange
takes place depends on the ________ of
the cell. However, the rate at which food
and oxygen are used up and waste products
are produced depends on the cell’s
_______.
Surface area; volume
Whiteboard review
Where is DNA found in a eukaryotic cell?
What is the function of DNA?
Nucleus; contains your genetic information
(traits)
Whiteboard review
What is the ratio of vowels to consonants
in the alphabet?
26 letters in the alphabet
A, E, I, O, U = 5 vowels
Leaves 21 consonants
5:21 or 5 to 21
Whiteboard review
Calculate the surface area, volume, and then
ratio of surface area to volume of a cell
(cube) with 10 cm sides.
S.A. = 10 x 10 x 6 = 600 cm2
Vol. = 10 x 10 x 10 = 1000 cm3
Ratio: 600:1000  6:10  3:5
Whiteboard review
Comparing a 1 cm per side cell and a 3 cm
per side cell…
1. Which of the two cells has the greater
volume?
2. Which of the two has the greater surface
area?
1. 3 cm cell
2. 3 cm cell
Whiteboard review
True or False…
Both volume and surface area increase with
cell size.
True
Whiteboard review
How would the function of the lysosome
organelle of a cell be impaired/more
difficult if the cell were to become too
large?
What about mitochondrion?
Lysosome = breaking down organic
molecules/organelles (too much to do)
Mitochondrion = energy production (not
enough produced)
Whiteboard review
How is a cell’s DNA like the books in a
library?
Books and DNA both contain information.
(DNA = genetic information).
Whiteboard review
As a cell increases in size, which increases
more rapidly, its surface area or its volume?
Volume increases much more rapidly than
surface area.
Whiteboard review
Which scenario is best for a cell?
A large ratio of surface area to
volume… or
A small ratio of surface area to
volume.
A large ratio of surface area to volume (6:1
is better than 2:1)