Ch. 2 CELLS

Ch. 2 Word Splash Cell Theory stem cells metabolism growth reproduction response Homeostasis nutrition differentiation prokaryotic eukaryotic binary fission PASSIVE TRANSPORT active transport cell division endocytosis exocytosis cell cycle MITOSIS

Pre-Assessment 1.When unspecialized stem cells give rise to specialized cells, what is this process called? A.Specialization B. MeiosisC. MitosisD. Differentiation 2. The maximum size of a cell is limited by _____. A.its need for enough surface area to make exchanges with its environment B.the number of organelles that can be packed inside C.the materials needed to build it D.the amount of food it needs to survive 3. What do limits on maximum cell size depend on? A.the number of organelles B.surface-to-volume ratio C.number of surrounding cells D. thickness of the cell membrane

How to Calculate Magnification When given a magnified picture, you can use the formula: magnification = length of scale bar (using ruler) / given scale bar value (read value) * Note: both values must be in the same unit before you divide them!

Here’s how to convert from mm (10 -3 ) to μm (10 -6 ): 1mm = 1000μm

Ex: magnification = length of scale bar / given scale bar value magnification = _____ mm /.5 μm  ______ μm /.5 μm magnification = ______x

Magnification Practice Handout

Limiting Cell Size All cells grow, but growth is limited by the surface area to volume ratio Surface area (cell membrane) controls what enters and leaves the cell while the inside of the cell (volume) controls functions related to food/energy/waste

Small Cell Medium Cell Large Cell Cell radius0.25 units0.5 units1.25 units Surface Area (4Πr 2 ) 0.79 units3.14 units7.07 units Volume (4/3Πr 3 ) 0.06 units0.52 units1.77 units SA:V ratio13 : 16 : 14 : 1

Other Modifications to Help increase the SA:V ratio Smaller cells have larger SA to V ratios. To adapt to this concept, large animals don’t have large cells, instead they have more cells. Large cells may change from spherical to long and thin or they may have protrusions/folds to increase their surface area – Examples include nerve cells which are narrow and long and intestinal cells which have an increased surface area due to microvilli

Stem Cell Lab