CHAPTER 4 A TOUR OF THE CELL 4.2 Most cells are microscopic Objectives: 1) Be able to explain why cell size is limited. III. Surface area-to-volume ratio A. Surface Area(SA) 1. The measurement of the exterior of the cell 2. To calculate take the # of sides and multiply by the length and width of sides B. Volume 1. The measurement of the internal contents of the cell 2. To calculate multiply the length x width x I. Diffusion A. One of many ways cells transport materials throughout the cell B. Cell parts must not be too far from the cell membrane 1. Diffusion is very fast and efficient over short distances 2. Diffusion becomes slow and inefficient as distances become larger II. DNA limits cell size A. DNA contains the directions for all cell activity 1. For exampleProteins a. If cell is too large the DNA cannot make proteins fast enough to support the cells needs
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CHAPTER 4 A TOUR OF THE CELL 4.2 Most cells are microscopic Objectives:1) Be able to explain why cell size is limited. III. Surface area-to-volume.
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CHAPTER 4 A TOUR OF THE CELL
4.2 Most cells are microscopicObjectives: 1) Be able to explain why cell size is limited.
III. Surface area-to-volume ratioA. Surface Area(SA)
1. The measurement of the exterior of the cell2. To calculate take the # of sides and multiply by the length and width of sides
B. Volume1. The measurement of the internal contents of the cell2. To calculate multiply the length x width x height
I. DiffusionA. One of many ways cells transport materials throughout the cellB. Cell parts must not be too far from the cell membrane
1. Diffusion is very fast and efficient over short distances2. Diffusion becomes slow and inefficient as distances become larger
II. DNA limits cell sizeA. DNA contains the directions for all cell activity
1. For exampleProteinsa. If cell is too large the DNA cannot make proteins fast enough to
support the cells needs
L=1
W=1
H=1
SA= 6X1X1=6
Volume= 1X1X1=1
C. As a cell grows so to does its SA and volume1. The problem the volume increases faster than the
SA
W=2
H=2
L=2
SA=24Volume=8
4X the SA8X the volume
2. How does the SA-to-volume ratio affect the function of the cella. If cell size doubles, the cell would require
8x more nutrients & would have 8x more waste to excrete
1. SA would only increase by 4x2. The plasma membrane could not accommodate this increase
4.3 Prokaryotic cells are structurally simpler than eukaryotic cellsObjective: 1) Be able to briefly explain the difference between a prokaryotic cell and a eukaryotic cell.I. Prokaryotic vs. Eukaryotic
Prokaryotes Eukaryotes
No Nucleus (have a Nucleoid) Nucleus
No membrane bound organelles Membrane bound organelles
Cell membrane Cell membrane
Cytoplasm Cytoplasm
Ribosomes Ribosomes
I. Organelle IntroA. A specialized compartment that carries out 1 or
more specific functionsB. 4 basic functional groups