Protists Flashcards
Are protists a paraphyletic or monophyletic group?
Paraphyletic
Protists vary in:
Body plan, method of motility, nutrition type, mode of reproduction
Three main protist groups are:
Algae, slime molds, protozoa
Algae, slime molds, and protozoa are groups of:
Protists
Algae
Plant like protists
Slime molds
Fungus like protists
Protozoa
Animal like protists
Ecological importance of protists
Algae produce much of the O2 in the atmopshere. They support food chains as producers of energy. Slime molds are important decomposers. They are also parasites. Protozoa are decomposers and consumers that support food chains. They are also parasites.
How are protists a paraphyletic group?
All eukaryotes are protists except animals, fungi, and land plants, so protists are a paraphyletic group (i.e. not all descendants included)
Describe compartmentalization in the origin of eukaryotic cells
The loss of a cell wall in Eukaryote evolution resulted in the need to maintain the surface area to volume ratio and provide support. One theory is that the infolding of the cell membrane led to the ER and nuclear envelopes as organelles in a prokaryotic ancestor of eukaryotes, likely in Archaea. Eukaryotes evolved to have a more complex cytoskeleton, nucleus, nuclear envelope, plasma membrane, ER, and other organelles.
What happens to the surface area:volume ratio as the size of the sides of a box increase?
The surface area is proportional to the (length of the side)^2, but the volume is proportional to the side cubed, so the surface area to volume ratio decreases as the size of the box increases.
Describe the advantages of multicellularity.
The size of the organism can increase, it permits cell specialization, it allows the organism to increase the surface area to volume ratio, and the organism can better avoid predators as a multicellular organism.
Can protists be multicellular?
Yes, protists can be multicellular as well as unicellular and colonial.
Endosymbiotic theory
This theory states that eukaryote organelles may have evolved when large eukaryotic organisms engulfed smaller organisms and a symbiotic relationship arose, e.g. ancestral eukaryotes engulfed an aerobic bacteria to create the mitochondria organelle. Chloroplasts evolved similarly.
Colonial protists
A colony is when several individual organisms especially of the same species live together in close association. Colonial protists are individual protists that form a colony to act as a larger multicellular organism.
