# Lipids atoms 100 m 10 m 1 m 10 cm 1 cm 1 mm 100 µ m

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lipidsatoms100 m10 m1 m10 cm1 cm1 mm100µm10µm1µm100 nm10 nm1 nm0.1 nm1 meter (m) = 1.09 yards1 centimeter (cm)1 millimeter (mm)1 micrometer (µm)1 nanometer (nm)= 10–2(1/100) meter (1 cm = 0.4 inch)= 10–3(1/1000) meter= 10–6(1/1,000,000) meter= 10–9(1/1,000,000,000) meter
Section 2.1 Review40U N I T 1Cellular FunctionsAs you can see in Table 2.1, smallercells, such as those on the right, bene-fit from a much larger surface area tovolume ratio than do larger cells. In re-ality, no cells are perfect cubes orspheres and a great variety of shapesexist. For example, human nerve cellscan be very long, but to maintain a highenough surface area to volume ratio tosurvive, they are very slender.INFOBITAlthough most cells are aboutthe same size, there are excep-tions:Mycoplasma(at approxi-mately 0.2µm in diameter) isthe smallest cell yet discoveredand the single-celledAcetabularia sp. (at 5–7 cm) isone of the largest cells.Understanding Concepts1.Biologists accept that life begins at thecellular level of organization. Providetwo pieces of evidence to support thisview.2.What is the normal size range for mostcells? Explain why it is an advantagefor cells to be small.3.Calculate the volume and surface areaof 512 cubes with sides of 0.25 cm.Applying Inquiry/Communication Skills4.Two different types of cells have the fol-lowing dimensions. Cell #1 is 2 mm2 mm8 mm and cell #2 is 1 mm2 mm16 mm.a)Calculate the volumes of cell #1 and#2. How do they compare?b)Calculate the surface areas of thetwo cells. How do they compare?c)Calculate the surface area to vol-ume ratio for the two cells. How dothese values compare?d)What do the values in c) tell youabout the importance of cell shape?Making Connections7.An understanding of cells informs andaffects everyone.a)Explain how the cell theory relatesto other living organisms besideshumans, e.g., to a dog or anamoeba.b)Describe four ways that cells haveaffected your life.Use this information to explain hownerve cells can be very large (up to1 m in length).5.Cells were observed as early as 1665.Since that time, important new dis-coveries about the cell have occured.Research and construct a time-line ofobservation and discovery.6.Assume you are a 19th-century re-porter assigned to explain the impor-tance of the discovery of cells and thecell theory. Write a supported para-graph to tell your readers why suchdiscoveries are important to them.Refer to page 59,Investigation 2I n v e s t i g a t i o nOne (222)-cm cubeEight 1-cm cubesSixty-four 0.5-cm cubesSurface Area (cm2)244896Volume (cm3)888Surface Area to Volume Ratio3:16:112:1TABLE 2.1The Effect of Size per Cube Side on Surface Area and Volume
C H A P T E R 2Cell Structure and Function412.2Cell StructuresKey UnderstandingsWhen you have completed this section, you will be able to:distinguish between prokaryotic and eukaryotic cellsdescribe how cell structures manage various cell functionsexplain the fluid mosaic structure of membranesThere is no such thing as a typical cell,but all cells can be classifed according

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