1. Lecture 4 Cells
Reading: Chapter 6

2. All life is based on a unit of organization we call the cell There are two basic cell architectures:
Prokaryotic
Eukaryotic

3. Sizes of things

4. Prokaryotic Cells

5. Escherichia coli
Bacillus polymyxis

6. Eukaryotic Cells
Eukaryotic cells are much more complex than prokaryotic cells
Eukaryotic cells are usually much larger than prokaryotic cells
Most Prokaryotes are single celled
Many Eukaryotes are single celled
Many Eukaryotes are multi-celled

7. Animal Cell

8. Plant Cell

9. Some major differences between animal and plant cells
Plant cells have a cell wall
Plant cells have chloroplasts (plastids)
Plant cells have a central vacuole
Plant cells have plasmodesmata
Animal cells have lysosomes
Animal cells have centrioles
Many animal cells are ciliated

10. Similarities between plant and animal cells
Nucleus
Mitochondria
Endoplasmic reticulum
Golgi
Vesicles
Peroxisomes
Cytoskeleton
Centrosome
Flagella (some cells)

11. Things all cells (both prokaryotic and eukaryotic) have in common:
Plasma membrane
DNA
Central role for proteins
Same genetic code
Mechanism of protein synthesis
Ribosomes, mRNA, tRNA
Many metabolic pathways

12. Nucleus and cytoplasm (Eukaryotic cells)
Nucleus contains DNA
Bounded by two membranes
Inner and outer nuclear membrane
Nuclear pores
Nucleus contains no ribosomes
Site of most DNA and RNA synthesis
The cytoplasm includes everything between the plasma membrane and the nuclear membrane - ribosomes

13. nucleus

14. Ribosomes
Ribosomes are found bound to the ER (rough ER) and free in the cytosol
Ribosomes are the site of all protein synthesis
Ribosomes have no membrane as part of their structure (made of RNA and protein)

15. Endomembrane system Endoplasmic reticulum Golgi Transport vesicles
Smooth
Rough
Golgi
Transport vesicles
Central vacuole (plants)

16. Endoplasmic reticulum
Site of much protein synthesis
Site of most membrane synthesis

17. Golgi Stack of membrane sacks Processing and transport center
Transport is by vesicles ER
lysosomes
Plasma membrane

18. Lysosomes
Site of protein and polysaccharide degradation (animal cells)
Provides major protection from foreign microorganisms (bacteria and viruses)
pH inside is about 5 (low). This activates digestive enzymes

19. Vesicle transport systemER
Golgi
Plasma memb.
Lysozomes
Vacuoles
Vesicles
Exocytosis

20. Vacuoles Central vacuole (plants) Phagosome (phagocytic cells)
Amoeba
Macrophages
Contractile vacuole
Protists

21. Energy Mitochondria (all eukaryotic cells)
“powerhouse of the cell”
Site of respiration (O2 + CH  CO2 +H2O)
Major source of ATP
Chloroplasts (all eukaryotic plant cells)
Site of photosynthesis
H20 + CO2 + light  glucose + O2
Ultimate source of chemical energy for most of life

22. Mitochondria Two membranes Have DNA and ribosomes
Inner mitochondrial membrane
Site of respiration
Outer mitochondrial membrane
Have DNA and ribosomes

23. Chloroplasts Three membranes Have DNA and ribosomes Outer Inner
Thylakoid (site of photosynthesis)
Have DNA and ribosomes

24. Other membrane bound organelles
Plastids (related to chloroplasts)
Starch storage (roots)
Pigment (flowers)
Have DNA and ribosomes
Peroxisomes (both plants and animals)
Single membrane
H transfer reactions (to oxygen)
Detoxification
Protection from oxidative damage

25. Cytoskeleton
All protein

26. Microfilaments (thin filaments) Intermediate filaments
Microtubules
α and β tubulin
Microfilaments (thin filaments)
actin
Intermediate filaments
(more than a dozen types with a similar overall structure)
Thick filaments (muscle)
myosin

28. Microtubules and transport in cell
Molecular motors
Molecular “walking machines”
Can work on both micro- filaments and microtubules

29. Microtubules and cell movement
Flagella
Cilia

30. Flagellum and Cilium Structure
Dynein = molecular motor

31. How does it work?

32. Microtubules and chromosome movement
Centrioles (animal cells)
Organize flagella
Organize spindle
Cell centers (plant cells)

33. Figure 12.5

34. Actin and cell movements
Membrane and cytoplasmic movements involve microfilaments

35. Structures outside the plasma membrane
Cell walls (plants, fungi, many protists)
Extracellular matrix (animals)
Polysaccharides (mucus, slime)
Junctions

36. Plant cell walls

37. Extra cellular matrix

38. Junctions