This document summarizes key cellular structures and processes. It describes mitochondria and chloroplasts, the cytoskeleton, and plasma membranes. It then explains different types of membrane transport including diffusion, osmosis, and various passive and active transport mechanisms.

1. Mitochondria
• Found in all eukaryotic cells.
• Responsible for energy production.

2. Chloroplasts
• Found only in eukaryotic cells such as plants
and algae.
• Site of photosynthesis.

3. Cytoskeleton

4. Cytoskeleton
• Made of long, thin,
protein filaments.
– Three sizes
• Microfilaments
• Intermediate filaments
• Microtubules
• Provides internal cell
structure.
• Anchor and connect
organelles.
• Move parts and products.

5. What is the
nature of cell
membranes?

6. Plasma Membrane
• Fluid mosaics of phospholipids, proteins and
carbohydrates.

7. Plasma Membrane
• Phospholipids provide basic architecture.
– Have hydrophilic tails and hydrophobic heads.

8. Plasma Membrane
• Proteins act as
channels,
recognition
molecules,
carrier proteins,
etc.
• Carbohydrates
help connect
cells and play a
role in
identification.

9. Diffusion
• Net
movement of
molecules
from areas of
high
concentration
to areas of
low
concentration.
• No energy
required.

10. Diffusion
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11. Osmosis
• Type of diffusion.
• Movement of water across semipermeable membrane from
area of high water concentration to area of low water
concentration.

12. Effect of osmosis on cells in various
solutions
• Hypotonic solutions
– High concentration of
water in extracellular
fluid compared to
inside the cells
causes net movement
of water into the cell.
– Results in increased
cell size.
– Can cause cell to
burst.

13. Effect of osmosis on cells in various
solutions
• Isotonic solutions
– Concentrations of
water inside and
outside of the cell
are equal.
– Results in no net
movement of
water.
– Cell size remains
the same.

14. Effect of osmosis on cells in various
solutions
• Hypertonic
solutions
– Concentration of
water in cell
exceeds that
outside of cell.
– Results in net
movement of water
out of the cell.
– Cell shrinks.

15. Membrane transport
• Large or hydrophilic
substance cannot pass
freely through the
membrane.
• To move them through
the membrane, must
have channel proteins or
carrier proteins.

16. Passive Transport: Ion Channels
• Ions are hydrophilic and the channel must be
open for the ion to pass through the channel.
• Selective for each ion.
• Ion moves down concentration gradient.

17. Passive Transport: Facilitated
diffusion
• Molecule enters protein carrier.
• Induces protein shape change allowing molecule to
exit the carrier.

18. Passive Transport: Facilitated
diffusion
• Selective for each molecule.
• Molecule moves down concentration gradient.

19. Passive Transport: Facilitated
diffusion
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20. Active Transport
• Uses carrier protein.
• Moves molecules against their concentration
gradient.
• Requires ATP as an energy source.

21. Active Transport
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22. Active Transport

23. Endocytosis
• Cells absorb outside material by inverting plasma
membrane to form a vesicle that encases the
material.

24. Exocytosis
• Moving molecules, particles, and other substances
contained in vesicles across the plasma
membrane and out of the cell.