Kingdom Protista

Paraphyletic group - grade (adaptive zone)

Some Protozoans are colonial but are not metazoans

Metazoans - more than one type of nonreproductive (somatic) cell

- embryonic development

General Characteristics:

nucleus is membrane-bound (eukaryote)

Ectoplasm: bases of cilia or flagella

organelles cytoplasm

Endoplasm: nucleus, organelles

A. Locomotion

Cilia and flagella - 9 + 2 arrangement of microtubules

- axoneme

- where axoneme enters body of cell - central pair ends and 9 pairs become 9 triplets.

- kinetosome or basal body - same in structure as centrioles

Pseudopodia

- hyaline cap

- actin/myosin interaction

- seen in ameboid cells

- lobopodia (large and blunt), filopodia (thin and branching), or reticulopodia (thin netlike mesh)

B. Excretion and Osmoregulation

osmoregulation - active maintenance of water and solute balance

contractile vacuoles

Protozoans get rid of metabolic waste (ammonia) by diffusion

C. Nutrition

autotroph -

heterotroph -

phagotrophs -

phagosome, lysosomes

osmotrophs - pinocytosis, facilitated diffusion or active transport

D. Reproduction

Asexual reproduction - fission mitosis




Sexual reproduction - isogametes or anisogametes

Syngamy - fertilization of individual gamete by another

Autogamy - gametes fuse within the same individual

Conjugation - exchange of gametic nuclei

Micronucleus undergoes meiosis = 4 haploid micronuclei

3 degenerate and remaining one divides into 2 haploid pronuclei

Each organism exchanges one pronuclei with the other

fusion to restore the diploid number of chromosomes

Why? gene recombination to increase genetic variation in pop.

E. Encystment and Excystment

cysts formed to withstand harsh environments. Protective covering.

Survival of some cysts stages up to 38 and 49 years.

- Can be regular part of life cycle or

- Can be the result of environmental change

Some of the organelles are reabsorbed: cilia, flagella

The Golgi apparatus secretes the cyst wall material which is carried to surface in vesicles.