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 1cm 2cm 3cm

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 : Volume LIMITS 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 ODWSODWS

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 ODWSODWS

Growing cells 1µm 2µm 3µm 4µm 5µm 6µm © 2010 Paul Billiet ODWSODWS

How are surface area and volume affected by growth? SA/V Volume / µm 3 Surface area / µm 2 Size / µm © 2010 Paul Billiet ODWSODWS

Comparing Surface Area and Volume changes © 2010 Paul Billiet ODWSODWS

Surface Area:Volume Ratio © 2010 Paul Billiet ODWSODWS

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 ODWSODWS

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

Flatten into a thin film Chick blastodisc Image Credits

Divide the cytoplasm into smaller volumes Early human embryos Zygote 8-cell Embryo Image Credit Image Credit

Multicellular organisms show the same adaptations Flowering plants have an extensive, branched rooting system to absorb water and minerals Image Credit

Multicellular organisms show the same adaptations Mammals have a long small intestine with internal folding to absorb digested food Image Credit C. Candalh, INSERM