1. Cells

2. Types of Cells Prokaryotic Eukaryotic No nucleus
No membrane-bound organelles
Eubacteria and Archaebacteria
Cleary defined nucleus
Membrane-bound organelles
Plants, animals, fungi & protista

3. Characteristics
Prokaryotic Cells
Eukaryotic Cells
Genetic Material
Located in nucleoid (region of cytoplasm not bounded by membrane)
Consists of a single DNA molecule
Located in nucleus
(membrane-bound compartment within the cytoplasm)
Made up of DNA molecules and protein. Organized into chromosomes.
Cytoplasm
Small ribosomes.
Photosynthetic membranes arising from the plasma membrane in some species.
Large ribosomes.
Membrane-bound
organelles present.
Organelles are compartments which perform specific cell functions.

4. Typical Prokaryotic Cell

5. Typical Eukaryotic Animal Cell

6. Typical Eukaryotic Plant Cell

8. Endomembrane System

10. Cell Membrane Fluid Mosaic Model
Fluid: Phospholipids in constant motion; proteins drift
Mosaic: Variety of proteins embedded and attached to membrane

11. I P PP Phospholipid bilayer Head Hydrophilic; polar Phosphate group
Head
Hydrophilic; polar
Phosphate group
Tail
Hydrophobic; nonpolar
Fatty acids
Proteins
Integral proteins (IP) •
Embedded within membrane
Transport, carriers, receptors
Peripheral proteins (PP)
Found on inner membrane surface
Points of attachment for cytoskeleton I P PP
Oligosaccharides
Surface carbohydrates
Short, branching chains
Involved in cell-to-cell recognition
Glycolipid if attached to lipid
Glycoprotein if attached to a
protein
Cholesterol
Maintains & restricts
membrane flexibility
and fluidity

13. Cell Transport Selectively permeable Hydrophobic core: •
Hydrophobic core: •
Nonpolar cross with ease
Small polar (H2
O) small enough to
pass between lipid molecules
Large polar and ions cannot pass
without help

15. Passive Transport Does not require cell energy
CHARACTERISTICS:
Does not require cell energy
Molecules move down (H to L) concentration gradient.
DIFFUSION:
Random movement of molecules
Down concentration gradient
Until equilibrium reached

17. OSMOSIS: Diffusion of water across selectively permeable membrane
ISOTONIC
HYPOTONIC
HYPERTONIC
Two sol’n with same solute conc.
Sol’n with lower solute conc.
Sol’n with higher solute conc.

18. ANIMAL CELLS
PLANT CELLS
Isotonic No net movement of water Normal state
for animal cells
Isotonic No net movement of water
Cell flaccid (limp). Plant wilts

19. Animal Plant Cell: Hypertonic Environ: Hypotonic Water enters cell
Cell swells & bursts
Cytolysis Cell dies
Cell swells
Cell wall pushes back
Cell becomes turgid
Normal state for
plant cells

20. Animals Plants Cell: Hypotonic Environ: Hypertonic Water exits cell
Cell shrinks
Crenates
Plasmolysis
Cell dies
Cell membrane pulls
away from
cell wall
Usually lethal

22. OSMOREGULATION-ADAPTATIONS
Paramecium
C=Hypertonic
E = Hypotonic
Water enters
Cell membrane less permeable to water Contractile vacuole pumps water out
Fresh Water Bony Fish
C = Hypertonic
Don’t drink water
Excrete large volumes of watery urine
Marine Bony Fish
C=Hypotonic E=Hypertonic
Water exits
Drink large amounts of water. Gills pump excess salts out of body.
C = Cell E= Environment

24. Transport proteins are specific
ACILITATED
DIFFUSION •
Diffusion of solutes across membrane
With help of transport proteins
Passive transport
Transport proteins are specific
Model
Protein has 2 conformations
Solute binds to protein
Protein changes shape
Solute released to other side of membrane

26. Active Transport CHARACTERISTICS: Requires cell energy (ATP)
Materials moved against (L to H) conc. gradient
Na+/K+ Pumps .
Other Examples: Proton pumps: Mitochondria & chloroplasts
Involved in plant cell growth
Active Transport .

28. Cotransport 1 . Active transport of H+ creates H+ conc. gradient 2
. H_+ allowed to diffuse down
conc. gradient; sucrose tags along
Cotransport

30. Transport of Large Molecules
Endocytosis (1-4)
Intake of large molecules, solids, food
Material collects in pocket of cell membrane
Pocket pinches off forming vacuole
Exocytosis (5-8) •
Release of large molecules, solids, wastes from cell
Vacuole/vesicle fuses with cell membrane
Contents released to outside

31. RECEPTOR-MEDIATED ENDOCYTOSIS
 TYPES OF ENDOCYTOSIS
PHAGOCYTOSIS
Cell eating
Intake of solids, food, bacteria
Nonspecific
PINOCYTOSIS
Cell drinking
Intake of small droplets of liquid (oil)
RECEPTOR-MEDIATED ENDOCYTOSIS
Specific
Model
− Molecule binds to receptor protein
− Complex migrates to “coated” pit
− Pit pinches off forming vacuole
-Receptor protein returns to cell membrane