Download Honors Biology Chapter 4 Cell Size and Cell Type Notes 1-15

Cell Size: Surface Area to Volume
Scale of the Universe
Most cells are very small and can’t be observed with the
naked eye.
 Bacteria are the smallest cells <10 µm
o .2 µm diameters
 Eukaryotic cells are larger, most between 10-100 µm
o Bird eggs are large cells
o Muscle cells and nerve cells are very long
What limits cell size?
 Function
o Minimum size must be large enough to contain
DNA, proteins and internal structures needed for
survival and reproduction
 Resource needs
o Maximum size must be based on the supply of
nutrients and oxygen to the cell, as well as waste
removal.
Surface Area = 96 mm2
Volume = 64 mm3
What is the relationship between Surface Area and
Volume?
Surface Area = Length X Width X 6 (Number of sides)
Volume = Length X Width X Depth
 Large cells have more surface area and volume than
smaller cells
 Smaller cells, however, have larger surface area to
volume ratios
Is it better to be made out of 1 big cell or many smaller
cells?
Many small cells
Larger cell has greater volume, which means:
 More chemical reactions
 Greater need for resources
 Greater waste production
 Greater heat production
Smaller SA/V ratio makes it difficult to acquire
necessary resources while removing waste and heat.
http://www.youtube.com/watch?v=xuG4ZZ1GbzI
Cells
All cells share some common characteristics:
1. Plasma membrane – phospholipid bilayer that serves
as the barrier between what is inside/outside the cell.
2. Genetic material – all cells have DNA for their
heritable material
3. Ribosomes – organelles that build proteins based on
the information stored in the DNA.
4. Cytoplasm – organelles and fluid inside the plasma
membrane, excluding the nucleus.
Prokaryotic Cells vs. Eukaryotic Cells
Prokaryotic Cells - All Bacterial Cells
Pro = Before
Karyote = Kernel = Nucleus
Prokaryotic cells
lack membrane
bound organelles
Small Cells
Generally range from
0-10 micrometers (µm)
Nucleoid Region – Nucleus-like region where the DNA
inside a prokaryotic cell is coiled. Not a nucleus, no
membrane.
Cell Wall – located beyond the plasma membrane. Helps
protect and maintain the shape of the cell. Not made of
cellulose.
Capsule – located outside the cell wall of some
prokaryotes. Sticky layer that adds protection and allows
cells to stick to surfaces.
Pili (Pilus)/Fimbriae – short projections that help cells
attach to surfaces.
Prokaryotic Flagella – long projections that propel the cell
through its liquid environment.
Eukaryotic Cells – Protist, Plant, Fungus and Animal Cells
Eu = True
Karyote = Kernel = Nucleus
Eukaryotes have many different membrane bound
compartments called organelles that carry-out specific
functions for the cell.
 Cellular metabolism – chemical activities of the cell
o Many take place in these compartments
 Many important molecules are embedded into the
membranes of these organelles.
Eukaryotic cells have organelles with and without
membranes.
Larger Cells
Generally range from 10-100 micrometers (µm)
Plant and Animal cells share many similar organelles:





Nucleus
Mitochondria
Ribosomes
Vesicles
Peroxisomes
Plants
 Cell wall
 Chloroplast
 Large Central
Vacuole





Smooth/Rough ER
Lysosomes
Golgi Apparatus
Cytoskeleton
Others
Animals
 Centrioles
 Flagella*