CELLS AND SIZES (2.1). Can you arrange these items from biggest to smallest? Click the next slide to see the answer!

CELLS AND SIZES

(2.1)

Can you arrange these items from biggest to smallest?

Click the next slide to see the answer!

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!

1. How many millimeters in a meter?2. How many micrometers in a millimeter?3. How many nanometers in a micrometer?4. How many nanometers in a millimeter?5. Convert 50 μm to millimeters.6. Convert 100 nm to micrometers.7. Convert 10 mm to nanometers.8. Convert 20 mm to micrometers.More practice here:

http://www.sciencegeek.net/Chemistry/taters/Unit0Metrics.htm

ANSWERS!

1. How many millimeters in a meter? 10002. How many micrometers in a millimeter? 10003. How many nanometers in a micrometer? 10004. How many nanometers in a millimeter? 1 000

0005. Convert 50 μm to millimeters. 0.05 mm6. Convert 100 nm to micrometers. 0.1 μm 7. Convert 10 mm to nanometers. 10 000 000 nm8. Convert 20 mm to micrometers. 20 000 μm

What is the ACTUAL size of

this stoma?

http://i-biology.net

CALCULATE THE MAGNIFICATION OF DRAWINGS AND THE ACTUAL SIZE OF SPECIMENS IN IMAGES OF KNOWN MAGNIFICATION (2.1.5)

Method #1. Using Scale BarsFirst calculate the scale on the scale bar:

Scale length = 20 μmRuler length 15 mm = 1.33μm per mm

Then measure the image with the ruler:x μm is 60 mm on the imageNow calculate the true length:1.33 x 60 =

80 μm(scale) (image length)

http://i-biology.net

TIP! Always measure in mm – it will make your life easier, trust me!

What is the ACTUAL diameter of this egg cell?

http://i-biology.net

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 MagnificationMEASURE the length of the cell80 mm (remember always use mm!)

DIVIDE by the magnification given80mm = 0.00089 mm90 000

CONVERT to a whole number = 890 nmRemember to:

MEASURE DIVIDE CONVERT

FIND THE REAL SIZE OF THESE CELLS USING THE MAGNIFICATION:

http://i-biology.net

http://i-biology.net

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?

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 bar20 mm (remember always use mm!)

CONVERT to scale bar units1 mm = 20 000 μm DIVIDE by the scale bar label20 000 μm = 2 000 x10 μm

http://i-biology.net

Remember to: MEASURE

CONVERT DIVIDE

http://i-biology.net

More Practice!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.

http://i-biology.net

Remember to: MEASURE

DIVIDE CONVERT

MEASURE = 250 mmDIVIDE = 250 mm/350 x = 0.714 mmCONVERT = 714 μm

More Practice!A sperm cell as a tail of 50µm long. A student draws it

75 mm long. Calculate the magnification.

http://i-biology.net

Remember to: MEASURE

CONVERT

DIVIDEMEASURE = 75 mmCONVERT = 75 000 μmDIVIDE = 75 000 μm/ 50 μm = 1 500 x