Download Chapter 3 Section 2 - Blue Earth Area Schools

Chapter 3 Section 2
Cell Features
Objectives
1.
2.
3.
4.
5.
List the three parts of the cell theory
Determine why cells must be relatively
small
Compare the structure of prokaryotic
cells with that of eukaryotic cells
Describe the structure of cell membranes
Differentiate between the membrane
proteins structures and functions
Cell Theory

The research of
three different
scientists led to the
formation of the
cell theory.
– Schleiden
– Schwann
– Virchow
All living things are
made of at least 1
cell.
2. Cells are the basic
unit of structure and
function.
3. All cells arise from
existing cells.
1.
Cell Size
Cell Size limited by
surface area to
volume ratio.
 Need enough surface
area to service the
volume.

•Surface Area
does not increase
at the same rate
as volume
•Small cells more
efficient
Math Lab p. 56
Read Background
 Follow along steps 1-3 and see how they
calculate surface area, volume and the
ratio between the two.
 Answer analysis questions 1-3

Common features of all cells
1.
Cell membrane
– acts as a boundary
keeping internal from
the external.
2.
Cytoplasm
– All things inside the
cell other than the
nucleus.
3. Cytoskeleton
– Provides the interior
framework of the cell
similar to your
skeleton
4. Ribosomes
– The part of the cell
responsible for
protein synthesis.
Prokaryotes v Eukaryotes






Smallest simplest cells (115 µm)
No nucleus or membrane
bound organelles
Most successful
organisms
Small circle of DNA
Cell Wall outside of
membrane
May have a capsule
and/or flagella




More complex
Have nucleus and
organelles to allow for
complexity
DNA housed in the
nucleus
May have flagella or cilia
Cell Membrane

Semi-permeable lipid bilayer
– Phospholipids form layers with
embedded proteins
– Phospholipids are both polar
and non-polar
– Polar ends attracted to the
water inside and outside the cell
– Tails point away from water
Cell Membrane Structure
•Interior of membrane is then a large non-polar area
•Repels polar molecules and ions
•Allows lipids and lipid soluble substances through
•Helps maintain homeostasis
Cell Membrane Proteins


Held in place by
their areas of
polarity and nonpolarity
Protein “float”
around within the
bilayer in the fluid
mosaic model
Membrane proteins
1.
Marker Proteins
–
2.
Receptor Proteins
–
3.
Associated with
carbohydrate and aids in
cell identification and
recognition
Bind to specific signal
molecules outside the cell
causing an internal
change
Enzyme Proteins
–
Involved in biochemical
reactions
4. Transport Proteins
–
–
Allow for the movement
of specific molecule/ions
across the cell membrane
Sometimes called carrier
proteins