Protozoans

1
Protozoans

• Introduction

2
Protozoa

• Single celled organisms
• Many contain multiple nuclei
• Many different body forms

3
Structures

• Have a plasma membrane or multiple membranes as
  part of the pellicle secreted envelope around
  the protozoan
• May have alveoli sacs within the organism
• May have glycocalyx glycoproteins that are
  immunologically important
• Pellicular microtubules below the plasma
  membrane
• Arrangement varies by organism

4
Membranous Organelles

• Very diverse in this group
• Mitochondria
• Tubular rather than lamellar cristae or they are
  absent
• Single and large or sausage shaped
• Golgi Apparatus or Dictysome
• Elaborate in some
• Multiple function based on the type
• Large and/or multiple parabasal bodies of the
  flagella

5
Organelles (cont.)

• Microbodies dense granular matrix
• Oxidases and catalase peroxisome
• Makes H2 anaerobically hydrogenosomes
• Glyoxylate cycle that makes carbohydrates from
  fat glyoxosomes
• Release of contents out of cell extrusomes
  reside under the cell membrane and originate from
  the dictysome
• Release of toxic substances for defense - toxosome

6
Organelles (cont.)

• Kinetocyst captures food
• Hptocyst paralyzes prey
• Trichocyst mechanical resistance to predators
• Mucocyst secrete protective coating
• Cytoplasm has various different states
• Endoplasm center zone that has a sol state
• Ectoplasm peripheral zone that has a gel state

7
Nucleus

• Protozoans are eukaryotic
• DNA is as chromosomes associated with histones
• Nucleus has a membrane, with various shapes
  possible
• Double membrane, may or may not disappear during
  mitosis
• Micronuclei in the reproductive stage meiosis
  prior to sexual reproduction (conjugation)
• Macronuclei somatic cell cell metabolism and
  growth, no meiosis
• Endosomes internal bodies that are the nucleoli

8
Locomotive Organelles

• Pseudopodia used for locomotion and feeding
• 4 types
• Lobopodia finger shaped with round tips both
  ecto- and endoplasm
• Filopodia slender, sharp pointed organelles tat
  are only ectoplasm unbranched
• Rhizopodia branch excessively and may fuse to
  form net-like structure
• Axopodia like filopodia but also contain and
  axial filament of microtubules back into the cell
  interior

9
Locomotive Organelles (cont.)

• Undulipodia cilia and flagella
• Cilia have a kinetosome and axoneme in the 92
  arrangement
• Body cilia somatic ciliature are in rows
  (kineties) and are composed of kinetids basic
  unit of structure
• Flagella whiplike central axoneme that arises
  from the kinetosome (similar to centrioles)
• Lie in the bottom of the flagellar pocket or
  reservoirs
• 2 or more flagella are called heterokonts
• Flagella, kinetosome and associated organelles
  are the mastigont or mastigont system

10
Cilia Ultrastructure
11
Reproduction

• Asexual
• Binary fission
• Symmetrogenic between kinetosomes or flagellar
  rows
• Homothetogenic across kinetics
• Sexual