6PROTOZOA 2
6PROTOZOA
INTRODUCTION
Parasitism
A specific type of interaction between two organisms
Host-parasite interactions often operate over a longer timescale than those seen with other pathogens
Results in significant host-parasite interaction at the cellular and organismal level
E.g.
Parasites that alter the behavior of the host
Giardia lamblia – induce biochemical change in the host cells at the site of infection (duodenal epithelium)
Parasites – have life cycles that often involve several hosts (survival and transmission between different hosts requires the parasite to exhibit more than one physiologically distinct form)
Habitats
Parasites
Some – inhabit only one site throughout their life cycle
Most – move to various sites within the body (require the formation of motile cellular forms, which will produce a significant change in the physiology and morphology of the parasite as a result of environmental change)
Life cycles involving more than one host organism – greater changes
Reasons why parasites move to various sites in with the host:
Driven by evasion of host immune attack
To aid transmission
Physiology of parasitic protozoa
Parasitic protozoa
Single-celled eukaryotic organisms
Utilize flagella, cilia, or amoeboid movement for motility
Some species – may exhibit more than one form of motility
All pathogenic protozoa – heterotrophs
Carbohydrates or Amino acids – major source of carbon and energy
Some parasitic protozoa – utilize oxygen to generate energy through oxidative phosphorylation
Many protozoan parasites – lack functional mitochondria; as a result, they exhibit a fermentative metabolism that functions even in the presence of oxygen
Metabolism of parasites – highly adapted
Unique organelles – kienetoplasts, hydrogenosomes
Synthetic pathways found in other eukaryotes – absent, because many metabolic intermediates/precursors are actively scavenged from their environment (minimizes energy expenditure, which is finely balanced in parasites and means that
INTRODUCTION
Parasitism
A specific type of interaction between two organisms
Host-parasite interactions often operate over a longer timescale than those seen with other pathogens
Results in significant host-parasite interaction at the cellular and organismal level
E.g.
Parasites that alter the behavior of the host
Giardia lamblia – induce biochemical change in the host cells at the site of infection (duodenal epithelium)
Parasites – have life cycles that often involve several hosts (survival and transmission between different hosts requires the parasite to exhibit more than one physiologically distinct form)
Habitats
Parasites
Some – inhabit only one site throughout their life cycle
Most – move to various sites within the body (require the formation of motile cellular forms, which will produce a significant change in the physiology and morphology of the parasite as a result of environmental change)
Life cycles involving more than one host organism – greater changes
Reasons why parasites move to various sites in with the host:
Driven by evasion of host immune attack
To aid transmission
Physiology of parasitic protozoa
Parasitic protozoa
Single-celled eukaryotic organisms
Utilize flagella, cilia, or amoeboid movement for motility
Some species – may exhibit more than one form of motility
All pathogenic protozoa – heterotrophs
Carbohydrates or Amino acids – major source of carbon and energy
Some parasitic protozoa – utilize oxygen to generate energy through oxidative phosphorylation
Many protozoan parasites – lack functional mitochondria; as a result, they exhibit a fermentative metabolism that functions even in the presence of oxygen
Metabolism of parasites – highly adapted
Unique organelles – kienetoplasts, hydrogenosomes
Synthetic pathways found in other eukaryotes – absent, because many metabolic intermediates/precursors are actively scavenged from their environment (minimizes energy expenditure, which is finely balanced in parasites and means that