CELLS AND SIZES (2.1)

Can you arrange these items from biggest to smallest? Virus Atom Plant cell Bacteria Human DNA Frog egg Chicken egg Click the next slide to see the answer!

Human Chicken egg Frog egg Plant cell Bacteria Virus DNA Atom

1. molecules (1 nanometer = 1 nm). 2. cell membrane thickness (10 nm). COMPARE THE RELATIVE SIZES OF MOLECULES, CELL MEMBRANE THICKNESS, VIRUSES, BACTERIA, ORGANELLES AND CELLS (2.1.4) Relative sizes: 1. molecules (1 nanometer = 1 nm). 2. cell membrane thickness (10 nm). 3. virus (100 nm). 4. bacteria (1micrometer or 1 μm). 5. organelles (less 10μm). 6. cells (<100 μm – plants cells are larger than animal cells) http://click4biology.info/c4b/2/cell2.1.htm#size

RECAP: SI UNITS OF MEASUREMENT http://wps.prenhall.com/wps/media/objects/165/169061/GIFS/table1.5.gif

PRACTICE CONVERSIONS! How many millimeters in a meter? How many micrometers in a millimeter? How many nanometers in a micrometer? How many nanometers in a millimeter? Convert 50 μm to millimeters. Convert 100 nm to micrometers. Convert 10 mm to nanometers. Convert 20 mm to micrometers. More practice here: http://www.sciencegeek.net/Chemistry/taters/Unit0Metrics.htm

ANSWERS! How many millimeters in a meter? 1000 How many micrometers in a millimeter? 1000 How many nanometers in a micrometer? 1000 How many nanometers in a millimeter? 1 000 000 Convert 50 μm to millimeters. 0.05 mm Convert 100 nm to micrometers. 0.1 μm Convert 10 mm to nanometers. 10 000 000 nm Convert 20 mm to micrometers. 20 000 μm

What is the ACTUAL size of this stoma? CALCULATE THE MAGNIFICATION OF DRAWINGS AND THE ACTUAL SIZE OF SPECIMENS IN IMAGES OF KNOWN MAGNIFICATION (2.1.5) What is the ACTUAL size of this stoma? http://i-biology.net

Method #1. Using Scale Bars First calculate the scale on the scale bar: Scale length = 20 μm Ruler length 15 mm = 1.33μm per mm Then measure the image with the ruler: x μm is 60 mm on the image http://i-biology.net Now calculate the true length: 1.33 x 60 = 80 μm (scale) (image length) TIP! Always measure in mm – it will make your life easier, trust me!

What is the ACTUAL diameter of this egg cell?

What is the ACTUAL size of this bacterial cell? CALCULATE THE MAGNIFICATION OF DRAWINGS AND THE ACTUAL SIZE OF SPECIMENS IN IMAGES OF KNOWN MAGNIFICATION (2.1.5) What is the ACTUAL size of this bacterial cell? http://i-biology.net

Method #2. Using Magnification MEASURE the length of the cell 80 mm (remember always use mm!) DIVIDE by the magnification given 80mm = 0.00089 mm 90 000 CONVERT to a whole number = 890 nm Remember to: MEASURE DIVIDE CONVERT http://i-biology.net

FIND THE REAL SIZE OF THESE CELLS USING THE MAGNIFICATION: http://i-biology.net

What is the MAGNIFICATION of this plant cell image? CALCULATE THE MAGNIFICATION OF DRAWINGS AND THE ACTUAL SIZE OF SPECIMENS IN IMAGES OF KNOWN MAGNIFICATION (2.1.5) What is the MAGNIFICATION of this plant cell image? http://i-biology.net

MEASURE the length of the scale bar CALCULATE THE MAGNIFICATION OF DRAWINGS AND THE ACTUAL SIZE OF SPECIMENS IN IMAGES OF KNOWN MAGNIFICATION (2.1.5) MEASURE the length of the scale bar 20 mm (remember always use mm!) CONVERT to scale bar units 1 mm = 20 000 μm http://i-biology.net DIVIDE by the scale bar label 20 000 μm = 2 000 x 10 μm Remember to: MEASURE CONVERT DIVIDE

http://i-biology.net

More Practice! Remember to: MEASURE DIVIDE CONVERT MEASURE = 250 mm A student views an image of a cell magnified 350 times. The image is 250 mm long. Calculate the actual length of the sample in the image. Remember to: MEASURE DIVIDE CONVERT MEASURE = 250 mm DIVIDE = 250 mm/350 x = 0.714 mm CONVERT = 714 μm http://i-biology.net

More Practice! Remember to: MEASURE CONVERT DIVIDE MEASURE = 75 mm A sperm cell as a tail of 50µm long. A student draws it 75 mm long. Calculate the magnification. Remember to: MEASURE CONVERT DIVIDE MEASURE = 75 mm CONVERT = 75 000 μm DIVIDE = 75 000 μm/ 50 μm = 1 500 x http://i-biology.net