the cell and its basic components dr. vindman ap biology unit 2
TRANSCRIPT
The Cell and its basic components
Dr. Vindman AP Biology Unit 2
What is a cell
• It is the basic unit at which the quality of life begins so….– It has a metabolism (does energy conversion)– It has the ability to sense and respond to change– It can reproduce – A population of cells can evolve– What else?
Cells
100X magnification
400X magnification
What things are found in all cells?
How big can a cell be?
• Cells must take in an energy source, move all necessary materials in and all waste products out.
• All of this must go through the cell_________ and ________ throughout the cytoplasm.
Diffusion and cell size
• At your lab stations find phenolphthalein agar cubes.
• There should be 3 different sized cubes.• USE A SPOON to Place these cubes in an acetic
acid (vinegar) for 15 minutes
Fill in the following chart while you wait Cube dimensions
Surface area of cube
Volume of cube
SA : Volume
1cm cube
2cm cube
3cm cube
Measure distance of diffusion
Cube size
Distance of color change mm
1cm2cm3cm
Answer and then turn in
1. Which cube has the highest surface are to volume ratio?
2. Which cube had the highest percentage of its volume experience a color change
3. How is this relevant to the cells ability to perform the functions necessary to be alive? (There is more than one function effected)
Surface Area : VolumeLIMITS TO SIZE
Volume
• Volume determines the amount metabolism in the cytoplasm
• Metabolism will require import of precursors
• Metabolism will result in the export of secretions
• And the export of excretory products
© 2010 Paul Billiet ODWS
Surface area
• Surface area will determine the exchange of materials between the cell and its environment
• Bigger cells will metabolize more• But they will need more surface to
support that metabolism• And the sites of metabolism in bigger
cells will be further from the surface of the cell
© 2010 Paul Billiet ODWS
Growing cells
1µm
2µm
3µm
4µm
5µm
6µm© 2010 Paul Billiet ODWS
How are surface area and volume affected by growth?
11.21.5236
216125642781
2161509654246
654321
SA/V
Volume / µm3
Surface area / µm2
Size / µm
© 2010 Paul Billiet ODWS
Comparing Surface Area and Volume changes
0
100
200
300
400
500
600
700
800
900
1000
0 1 2 3 4 5 6 7 8 9 10
Size / µm
Surface areaVolume
© 2010 Paul Billiet ODWS
Surface Area:Volume Ratio
0
1
2
3
4
5
6
0 1 2 3 4 5 6 7 8 9 10
Size / µm
SA
/V
© 2010 Paul Billiet ODWS
Solving the problem
• Bigger cells have a greater metabolism than smaller cells
• BUT bigger cells have a proportionally less surface for exchange
• How to increase surface area with increasing size?
© 2010 Paul Billiet ODWS
With a partner, come up with 9 examples where increased surface
area is an adaptation.
Throw out extensions
Microvilli of small intestine epithelium
Image Credit www.cytochemistry.net/
Flatten into a thin film
Chick blastodisc
Image Credits http://anatomia.uw.hu/
Divide the cytoplasm into smaller volumes
Early human embryos
Zygote
8-cell Embryo
Image Credit http://www.advancedfertility.com/ Image Credit http://www.rmfcfertility.com/
Multicellular organisms show the same adaptations
• Flowering plants have an extensive, branched rooting system to absorb water and minerals
Image Credit http://ecomerge.blogspot.com
Multicellular organisms show the same adaptations
• Mammals have a long small intestine with internal folding to absorb digested food
Image Credit C. Candalh, INSERM