The Cell and its basic components Dr. Vindman AP Biology Unit 2.

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