Inveterate Zoology

1. BIOL 201:
Invertebrate Zoology
Chapter 2: Introduction to Protozoa
Rob Swatski
Assistant Professor of Biology
HACC-York

2. Eukaryotes
Domain
Eukarya
Protozoa are
animal-like
protists
Classification
continually
changes
Membrane-
bound nucleus
& organelles
2

3. Protozoa
Most unicellular
Some colonial
(ancestors of
plants & animals)
Most motile
Incredible
diversity
3

4. Eukaryotic
Cells
Diversity of
specialized
organelles
Cell membrane &
cytoplasm
Double-membraned
nucleus,
mitochondria, &
chloroplasts
Internal membrane
system
4

5. 5

6. Cytoplasm
Fluid enclosed
by cell
membrane
Ectoplasm:
outer, stiff
portion
Endoplasm:
inner, fluid
portion
6

7. Cell
Membrane
Phospholipid
bilayer with
proteins
Barrier to the
external
environment
Selective passage
of molecules
Glycocalyx
Endocytosis &
exocytosis
7

8. 8

9. Internal
Membrane
System
Compartmentalizes
the cell
Endoplasmic
reticulum (ER)
Golgi bodies
Lysosomes
9

10. 10
Cytoskeleton

11. Cytoskeleton
3-D network of
protein fibers
Microfilaments
(actin)
Microtubules
Dynamic
11

12. 12
Microfilaments

13. Microtubules 13

14. Functions of the
Cytoskeleton
Cell motility:
cilia, flagella,
pseudopodia
Maintains
cell shape
Regulates
cell division
Vesicular
transport
14

15. 15
Cell
Motility
Motor molecules
(dynein) change shape
in the presence of ATP
Dynein arms grab,
move, & release outer
MT’s
MT doublets flex,
bending cilium or
flagellum
Treadmilling

16. 16

17. 17

18. 18
Cilia &
Flagella
Both made of MT core
(axoneme) sheathed
by plasma membrane
(9x2)+2 MT
arrangement
Arises from &
anchored to cell by
basal body (9x3)+0
Motor protein
(dynein) drives
bending movement

19. Cilia
Many
Short
Sweep
materials across
cell (oar-like)
Flagella
Fewer
Long
Move entire cell
(whip-like)
19

20. 20
Cilia

21. Cilia
21

22. 22
Basal body
Cilium or
Flagellum

23. (9x2)+2
23

24. Flagella
24

25. Base-to-tip wave
propagation
Longitudinal
forces provide
forward thrust
Flagellar
propulsion 25

26. Ciliary
propulsion Metachronal waves26

27. 27
Cell motility using actin

28. Pseudopodia
Used for locomotion,
feeding, & endocytosis
Dynamic disassembly &
assembly of actin
Ectoplasm (gel)
converted into
endoplasm (fluid)
Contractile ectoplasm
provides force to move
cytoplasm forward
28

29. 29
Amoeboid movement

30. 30

31. Protozoan
Physiology
Same rules as in
metazoans
Environmental
effects may be
more significant
Ectothermic
Large surface area-
to-volume ratio
31

32. Uptake By
Cells
Endocytosis:
extracellular uptake
Micropinocytosis:
water, ions, small
molecules
Macropinocytosis:
proteins &
macromolecules
Phagocytosis:
bacteria & protozoans
in food vacuoles
32

33. 33

34. 34Micropinocytosis

35. 35Macropinocytosis

36. 36
Phagocytosis

37. Intracellular
Digestion
Engulfment
(phagocytosis): food
vacuoles fuse with
lysosomes
Intracellular Digestion:
mechanical/chemical
Absorption into
cytoplasm: products are
metabolized or stored
Elimination of
indigestible material via
exocytosis
37

38. Cell
Circulation
Cytoplasmic
circulation needed in
larger cells
Streaming: directional
transport within cell
or pseudopodium
Shuttling: the
movement of vesicles
along a MT
Cyclosis: flow travels
in a circuit
(Paramecium)
38

39. 39

40. Endosymbiosis
Heterotrophs often form
mutualistic symbioses
with autotrophs
Zoochlorellae:
photosynthetic symbionts
such as unicellular green
algae or diatoms
Zooxanthellae:
photosynthetic symbionts
such as nonmotile yellow
or brown dinoflagellates
Evolutionary value
40 Stentor

41. 41
Zoochlorellae (in Paramecium bursaria)

42. 42
Zoochlorellae
(in giant green
sea anemone)

43. 43
Zooxanthellae (in coral)

44. 44
Endosymbiosis

45. 45
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