1. The Fundamental Units of Life
CELLS
The Fundamental Units of Life

2. Cell Theory All organisms are composed of 1 or more cells.
The cell is the basic living unit, providing organization for all organisms.
All cells arise from preexisting cells.

3. Cells Are Small
Most are too small to be seen with the unaided eye…so Microscopes are used.
A Light Microscope uses visible light shone through glass lenses.
A “thin section” of specimen is required.
van Leeuwenhoek

4. Principles of Microscopy
LIGHT
REFRACTION
MAGNIFICATION
RESOLUTION

5. MAGNIFICATION Image size exceeds real size.
Achieved with convex lenses.
There are limits…
…involving the nature
of light.
First, you need enough
light to penetrate the thin
specimen.

6. RESOLUTION
Next, you need light of appropriate wavelength…or RESOLUTION is compromised.
A measure of clarity – of focus.
Minimum distance between two points that allow the points to be distinguishable.
Light microscopy not very useful below 0.2um.

7. RESOLUTION

8. Electron Microscopy Uses e- rather than light.
Electrons have a much shorter wavelength.
SEM = Scanning Electron Microscopy
TEM = Transmission Electron Microscopy

9. Electron Microscopy

10. Cells!

11. CELLS Eukaryotic Cells (animals, plants, fungi, protists)
Complex & relatively large.
Membrane-bound nucleus & organelles.
80-S Ribosomes.
Prokaryotic Cells (archaea, bacteria)
Simple & relatively small.
NO Membrane-bound nucleus & organelles.
70-S Ribosomes.

12. PROKARYOTIC EUKARYOTIC
CELLS
PROKARYOTIC EUKARYOTIC

13. EUKARYOTIC CELLS Organelles = “little organs” (not really)
Membrane-bound

14. ORGANELLES
Nucleus
Isolates the DNA & provides access to its hereditary information.
The “control center” of the cell (Transcription).

15. Nucleus Nuclear Envelope (a double membrane) Nucleolus Nucleoplasm
with Pores.
Nucleolus
rRNA
Proteins
Ribosomes
Nucleoplasm
with Chromatin/Chromosomes.

16. Ribosomes Not true organelles, more “structures”. Protein factories.
2 sub-units.
Free (in cytosol/cytoplasm), more for intracellular activities.
Bound (on E.R.), often for extracellular activities (secretion) & packaging within certain organelles.

17. Endomembrane System
Synthesis of Proteins & their transport into membranes and/or organelles.
Packaging of Proteins for transport out of the cell (secretion) or to other areas of the cell.
Modification of Proteins.
Transport of lipids, lipoproteins, glycoproteins, etc.

18. Endomembrane System Endoplasmic Reticulum (E.R.) Golgi Apparatus
Rough E.R.
Smooth E.R.
Golgi Apparatus
Vesicles
Lysosomes
(also, nuclear envelope, vacuoles, and plasma membrane)

19. Endoplasmic Reticulum
Network of interconnected membranes (continuous with the nuclear envelope).
Flattened or tubular Cisternae.

20. Rough E.R.
The site of protein synthesis, particularly secretory proteins.
Initial modification of proteins.
Especially, formation of Glycoproteins.
Formation (budding) of Transport Vesicles.
Formation of NEW Membrane =
Phospholipid Synthesis

21. Smooth E.R. Formation of Lipids, detoxification.
Lipid-derived hormones (steroids) are synthesized, including sex hormones (testosterone, etc.) in certain glands.
Solubilization of toxins (drugs, alcohol, caffeine, etc. ) in liver cells.
Calcium ion storage & release in muscle cells.

22. Golgi Apparatus
Manufacture, storage, modification, sorting, & shipping of ER-produced items (esp. secretion).
Addition of non-protein portions to protein molecules.

23. Golgi Apparatus Stacks of cisternae, with cis & trans faces.
Cis – receiving (takes in vesicles).
Trans – sending (gives rise to vesicles).

24. Lysosomes
Vesicles carrying digestive enzymes – hydrolytic (proteolytic) enzymes.
Animal Cells.
Digestion of food brought in by phagocytosis.

25. Lysosomes
Digestion and recycling of old & damaged organelles within the cell: Autophagy.

26. Endomembrane System

27. Vacuoles Large vesicles with particular functions. Food Vacuoles.
Contractile Vacuoles.
Central Vacuole w/ tonoplast in Plant Cells.
Storage.
Dissolved Solutes.
Dumping Ground.
Protection.
Shape.

28. Mitochondrion Site of cellular respiration = energy production.
Carbohydrates ATP
Not part of endomembrane system.
Have their own DNA, RNA, Proteins, and Ribosomes (70-S).
Grow and reproduce independently.
Animals, Plants, Fungi, Protists.

29. Mitochondrion Surrounded by a double membrane – an envelope.
Outer Membrane
Inner membrane (Cristae)
Matrix

30. Chloroplast
Site of Photosynthesis = acquisition of chemical energy from sunlight.
Sunlight + CO Carbohydrates
A plastid (not part of endomembrane system).
Have their own DNA, RNA, Proteins, and Ribosomes (70-S).
Grow and reproduce independently.
Plants, Protists.

31. Chloroplast Surrounded by a double membrane – an envelope.
Inner Membrane (Grana composed of stacked Thylakoids)
Outer Membrane
Stroma

32. Peroxisomes
Odd vesicles that carry Hydrogen to Oxygen, forming Hydrogen Peroxide (H2O2).
Used to break down larger molecules.
Detoxify alcohol in Liver Cells.

33. Cytoskeleton Fiber-like structures that lend organization.
Support (providing a scaffolding onto which organelles & vesicles can be organized).
Shape (maintain particular shape depending on the cell’s location and/or function).
Transport of materials around or out of the cell.
Motility of the whole cell from one location to another.

34. Cytoskeleton Microtubules Microfilaments Intermediate Filaments
Keratin Subunits
Tubulin
Actin
Keratin

35. Cytoskeleton Permanent Flagella Cilia Muscle Contraction
Scaffolding & Shape Maintenance

36. Cytoskeleton
Transient
Spindle Fibers
Transport filaments

37. Cell Wall OUTSIDE the Cell Membrane (technically, outside the cell!)
Various proteins & glycoproteins in Prokaryotes.
Cellulose in Plants.
Chitin in Fungi.

38. Eukaryotic Cell

39. Endosymbiont Theory

40. Onion Cells