Outline for Cell membrane
You have the cell organelle chart for that cell anatomy part of this test
Compare and contrast plants and animal cells
Animal Cell
Cell wall Absent
Shape Round (irregular shape)
Vacuole One or more small vacuoles
(much smaller than plant cells).
Centrioles Present in all animal cells
Chloroplast Animal cells don't have
chloroplasts.
Plant cell
Present (formed of cellulose)
Rectangular (fixed shape)
One, large central vacuole taking
up 90% of cell volume.
Only present in lower plant forms.
Plant cells have chloroplasts
because they make their own
food.
Cytoplasm Present
Present
Endoplasmic Reticulum Present
(Smooth and Rough)
Present
Ribosomes Present
Present
Mitochondria Present
Present
Plastids Absent
Present
Golgi Apparatus Present
Present
Plasma Membrane Only cell membrane
Microtubules/ Present
Microfilaments
Flagella May be found in some cells
Lysosomes Lysosomes occur in cytoplasm.
Nucleus Present
Cilia Present
Cell wall and a cell membrane
Present
May be found in some cells
Lysosomes usually not evident.
Present
It is very rare.
I.
compare and contrast prokaryote and eukaryote cells
The primary distinction is that eukaryotic cells have a "true" nucleus containing their
DNA, whereas prokaryotic cells do not have a nucleus. Both eukaryotes and prokaryotes
contain large RNA/protein structures called ribosomes, which produce protein. Prokaryotic
cells are usually much smaller than eukaryotic cells. Therefore, prokaryotes have a larger
surface-area-to-volume ratio, giving them a higher metabolic rate, a higher growth rate, and
as a consequence, a shorter generation time than eukaryotes.
II.
CELL MEMBRANE STRUCTURE
Boundary between cell contents and external environment
Regulates communication between the two environments
A.
III.
Fluid Mosaic Model
1.
Bilayer of Lipid with associated protein complexes
2.
Lipid Bilayer
a.
Phospholipid
Hydrophylic (Water-loving), and Hydrophobic (Water-hating), fatty acid chains
b.
Cholesterol
3.
Proteins
a.
Integral proteins(across whole membrane can act as carrier complexes)
Form Channels and Carrier molecules
b.
Surface proteins with Carbohydrates attached to lipids or proteins
(extracellular coat)
1.
Determines outside vs inside differences
2.
Different cells, tissues, organisms have different surfaces materials
3.
Attachment sites for Specific Chemicals (Control molecules,
Hormones, Antibodies), Viruses etc.
CELL MEMBRANE FUNCTIONS
A.
Passive Membrane Processes
1.
Diffusion
Movement of molecules, (kinetic energy is measured by temperature) From region of
high concentration to region of low concentration Passive movement, follows and
eliminates concentration gradient
a.
At Equilibrium - solute gradient eliminated
b.
Does not require the presence of energy or a membrane
c.
Free movement across permeable membranes
Diffusion Rates determined by
Magnitude of the Concentration Gradients (NUMBER OF SOLUTE MOLECULES)
Diffusion Across Membranes
d.
e.
f.
2.
Permeability of Membranes
Size of Surface Area that permits diffusion
Examples:
Oxygen across membranes in lungs and tissues
Resting neuron 20X more permeable to K+ than Na+
Changes in numbers of membrane channels
Increase in surface area (microvilli, PCT, intestinal ep.)
g.
h.
Osmosis
Diffusion of a solvent across a semipermeable membrane
Requires a semipermeable membrane separating two different fluid environments
a.
Passive movement of water (only)
b.
At Equilibrium, Eliminates solvent concentration gradient
c.
Biological systems solvent = water
d.
Implied - presence of non-diffusible soluble substances,
e.
Impermeable solutes - osmotically active, ex. blood proteins
Osmotic pressure
f.
Force exerted to oppose osmosis
g.
h.
i.
Distilled water osmotic pressure = 0
1.
Pressure effected by number of particles in solution, NOT the size of
the molecule
1.
Osmolarity = 1 mole of glucose = 1 osmole [1 osm](glucose)
2.
1 mole of sodium chloride = 2 osm (Na+, Cl-)
3.
measured by freezing point depression 1 osm = -1.86oC
4.
Plasma freezing point depression = -.56oC [0.3 osm]
Mixed solution = sum of osmolarity of each solute
Tonicity (strength)
1.
Isotonic (same strength) = the same solute concentration
2.
Hypotonic = a relatively lower solute concentration
3.
Hypertonic = a relatively higher solute concentration
Regulation of Blood Osmolarity (Negative feedback loop)
a. Hypothalamus
osmoreceptors
b. Posterior Pituitary ADH
c. Kidney
3.
B.
DCT & CD, permissive effect of ADH
Filtration
Movement of solute across a semipermeable membrane as a result of pressure
differences
Example: Movement of fluid across the glomerulus in the kidney
4.
Dialysis
Diffusion of solute across a semipermeable membrane as a result of concentration
differences
Example: Used in the artificial kidney machine
ACTIVE MEMBRANE PROCESSES Carrier Mediated Transport
1.
Carrier (Integral) proteins in plasma membrane (permeases)
2.
Characteristics similar to enzymes
a.
Specificity - interacts with specific molecules
b.
Competition - 2 slightly different molecules compete for permease site
c.
Saturation - Rate of transport increases until all sites are filled
Rate levels off (no increase).
3.
Facilitative Diffusion
1. Passive movement of solute across a semipermeable membrane
2. Requires Carrier (Integral) proteins in plasma membrane
3. Does Not Require ATP. Solutes move with the concentration gradient [H --> L]
4. Example: Movement of many nutrients across the intestinal epithelium
4.
Active Transport
0. Carrier (Integral) proteins in plasma membrane (permeases)
1. Energy dependent (Requires ATP) m
2. Movement of Solutes across a cell membrane against the concentration
Gradient
3. Solutes move against the concentration gradient. [L --> H]
4. Example: Concentration of iodine in a thyroid gland cell
5.
Endocytosis
0. CELL EATING Phagocytosis
Capture and transport particules into the cytoplasm through the formation of a
C.
D.
membranous vesicle.
Example: Feeding in the Amoeba
1. CELL DRINKING Pinocytosis
Capture and transport of fluids the cytoplasm through the formation of a
membranous vesicle.
Example:Movement of lipid droplets into an intestinal epithelial cell
6.
Exocytosis
The ejection of fluids or other materials by fusion of a vesicle with the cell membrane
CELL MEMBRANE RECEPTORS & REGULATORS
Structures on the cell membrane that bind to cirlculating molecules
1.
Control Substances (ex. Hormones, neurotransmitters)
2.
Antigens (RBC blood group antigens)
3.
Channels (ex. calcium channels)
4.
Channels WITH electrostatic or chemical GATEs
Isotonic, Hypotonic, and Hypertonic
IV.
V.
VI.
VII.
Predict the direction of water movement based on differences in three dfferent solute
concentrations in the EFC and how these differences effet animal use the terms that describe
the solute concentration inside and outside the animal cell, and the term describing the
resulting change to the animal cell
isotonic, hypertonic, hypotonic
animal
direction
effect on cell
VIII.
IX.
Isotonic
normal balanced flow in
both direction
no change
Hypertonic
Flow net out of cell
Hypotonic
net flow into the cell
cell crenatized and falls
out of solution
cell can rupture when
there is not enough stretch
in the membrane to take
all the water.
X.
predict te direction of water movement based on differences in three differenct solute
concentrations in the EFC and how these differences effect plant cells, describe the solute
concentration inside and outside the plant cell and the term describing he resulting change to
the plant cell
plant
direction
Isotonic
normal balanced flow in
both direction
effect on cell
no change
Hypertonic
Flow net out of cell, the
cell shrinks pulling away
from the cell wall
the cell shrinks pulling
away from the cell wallplasmolyzed.
Hypotonic
net flow into the cell
the cell membrane will
apply force to the cell
wall and if left in tap
water long enough will
rupture the cell wall and
the cell membrane.
XI.
XII.
XIII.
Distinguish among simple diffusion, osmosis, facilitated transport and active transport
Diffusion is the movement of molecules from an area of greater concentration to an area of
lesser concentration. e.g. Exchange of gases in the lungs or body tissues.
Osmosis is the diffusion of water through a semi-permeable membrane from an area of low
solute to an area of high solute concentration. Faciliated diffusion is the passive transport of
molecules down a concentration gradient. It is simply diffusion that involves a protein to
make diffusion happen more easily across a cell membrane.
Active transport is the moving of substances across the cell membrane using the cell's energy.
Molecules are moved against a concentration gradient, i.e they move from an area of lesser
concentration to an area of greater concentration. Tlhis is done by a carrier molecules which
gets its energy from ATP.