1. Animal-Like Protists:
Chapter Opener
Chapter 08
Animal-Like Protists:
The Protozoa
CH 8.1 – Evolutionary Perspective of the Protists
CH 8.2 – Life w/in a Single Plasma Membrane
CH 8.3 – Symbiotic Lifestyles 1

2. Evolutionary perspective
CH 8.1 – Evolutionary Perpective of the Protists
Evolutionary perspective
Fossil record indicates virtually all protist and animal phyla living today were present during the Cambian period (550 mya)
No fossil evidence of evolutionary path
Evidence comes from extant species and hypotheses of formation
Animation: Three Domains 2

3. Evolutionary perspective protozoan evolution
CH 8.1 – Evolutionary Perspective of the Protists
Evolutionary perspective protozoan evolution
Cyanobacteria were first successful species
Domain: Eubacteria
Kingdom: Monera
Endosymbiosis gave rise to more complex cellular structures
Developed nucleus, mitochondria, plastids and cytoskeleton
Became eukaryotic
Developed a variety of metabolic processes
Autotropic – plant-like
Heterotopic - animal- like 3

4. Evolutionary perspective polyphyletic
CH 8.1 – Evolutionary Perspective of the Protists
Evolutionary perspective polyphyletic
Protists probably arose from more than one ancestral moneran group
Between 7-45 phyla
Each phyla comes from a combination of different lineages 4

5. Evolutionary perspective polyphyletic
CH 8.1 – Evolutionary Perspective of the Protists
Evolutionary perspective polyphyletic 5

6. - 4 Protist Super Groups -
CH 8.1 – Evolutionary Perspective of the Protists
- 4 Protist Super Groups -
b) Amoebozoa
a) Excavata
d) Chromalveolata
c) Rhizaria 6

7. Protozoan taxonomy CH 8.2 – Life Within a Single Plasma Membrane
(Gr. Proto, first + zoa, animal)
Complete organism in which all life activities are carried on w/in a single plasma membrane
Chemoorganotrophic
Organisms that use organic compounds as a source of energy, electrons, & carbon for biosynthesis 7

8. Protozoan taxonomy Protozooloist Studies protozoa
CH 8.2 – Life Within a Single Plasma Membrane
Protozoan taxonomy
Figure 8.2
Protozooloist
Studies protozoa
Regard protozoa as a subkingdom (super group) of the phyla Protista
Classification is based on the types of nuclei, mode of reproduction, and mechanism of locomotion 8

9. Maintaining homeostasis – Structure
CH 8.2 – Life Within a Single Plasma Membrane
Maintaining homeostasis – Structure
Pellicle - plasma membrane of many protozoa is underlaid by a layer of microtubules that add rigidity and support to the membrane, but are flexible enough to bend
Ectoplasm – the portion of the cytoplasm just beneath the pellicle, is clear and firm
Endoplasm – inner most cytoplasm, granular, more fluid 9

10. Function in osmoregulation. More common in freshwater species.
CH 8.2 – Life Within a Single Plasma Membrane
Contractile vacuoles: fill with fluid and then expel the fluid outside the cell.
Function in osmoregulation.
More common in freshwater species.
Figure 8.2 10

11. Maintaining homeostasis – Nutrition
CH 8.2 – Life Within a Single Plasma Membrane
Maintaining homeostasis – Nutrition
Most ingest other organisms or products of other organisms
Cytopharynx – food ingested through specialized region analogous to a mouth
Food vacuoles fuse with enzyme containing lysosomes to digest food. Small particles diffuse out into cytoplasm 11

12. Egestion vacuoles contain the remaining food material
CH 8.2 – Life Within a Single Plasma Membrane
Egestion vacuoles contain the remaining food material
Cytopyge – acts as an anal pore and merges with egestion vacuole to remove waste 12

13. Maintaining homeostasis – Gas Exchange
CH 8.2 – Life Within a Single Plasma Membrane
Maintaining homeostasis – Gas Exchange
Large surface area allows efficient diffusion of O2 needed for cellular respiration & eliminating the CO2
Excretion of metabolic nitrogenous waste, ammonia also occurs through diffusion 13

14. Maintaining homeostasis – Reproduction
CH 8.2 – Life Within a Single Plasma Membrane
Maintaining homeostasis – Reproduction
Fission is the cell multiplication process in protozoa.
Binary fission: one individual splits into two equal sized individuals.
Animation: Binary Fission 14

15. Maintaining homeostasis – Reproduction
CH 8.2 – Life Within a Single Plasma Membrane
Maintaining homeostasis – Reproduction
Binary Fission:
Longitudinal: (Euglenoids)
Transverse: (Ciliates)
Figure 8.3 15

16. Maintaining homeostasis – Reproduction
CH 8.2 – Life Within a Single Plasma Membrane
Maintaining homeostasis – Reproduction
Fission
Budding: progeny cell much smaller than parent.
Multiple fission (schizogony): multiple nuclear divisions followed by multiple cytoplasmic divisions producing several offspring. 16

17. Maintaining homeostasis – Reproduction (Sexual)
CH 8.2 – Life Within a Single Plasma Membrane
Maintaining homeostasis – Reproduction (Sexual)
Many types of protists reproduce sexually as well as asexually.
Isogametes – all look alike.
Anisogametes – two different types.
Syngamy – gametes from two individuals fuse to form the zygote.
Autogamy – gametes from one individual fuse.
Conjugation – gametic nuclei are exchanged. 17

18. CH 8.3 – Symbiotic Lifestyles
Symbiosis: (Gr. Syn, with + bios, life) Intimate association between 2 organisms
Parasitism – one organism lives in or on a second organism
– Host – the organism upon which the parasite lives
Intermediate: host that supports juvenile stage
Definitive: host that supports sexually reproductive stage 18

19. Mutualistic: benefits both.
CH 8.3 – Symbiotic Lifestyles
Symbiosis (no harm)
Mutualistic: benefits both.
Commensalistic: one benefits, the other is neutral. 19