microbial mats and multicellularity #7 Flashcards
what is a microbial mat & where are they typically found?
multilayered sheet of prokaryotes & shallow seabeds
what does proximate causality mean?
molecular mechanisms
what does ultimate causality mean?
selective advantages
define simple (basic) multicellularity found in prokaryotes
cell-cell adhesion, intercellular communication
what are the 3 classes of simple multicellularity in prokaryotes?
filaments, aggregates, MMPs
what are filaments?
formation of long chains of cells, some of which elongate but do not divide/ linear or branched/ single or multiple layers / many clonal in origin
what are aggregates?
cells are embedded in a slimy self-produced matrix/ biofilms& systems/cells w/ distinct morphologies / extracellular matrix
what are MMPs?
magnetotactic bacteria
connected by tight
intercellular junctions/ only obligate mc bacteria/ fission of “whole organism”
what are the 2 ways that organisms are constrained as greater complexity evolve?
physical constraints, selection (+ environment) constraints
what are the 4 selective advantages of multicellularity?
- resistance to environmental stresses
- improved nutrient utilization
- resistance to predators
- division of labor
what are the selective disadvantages of multicellularity?
energetic costs - synthesis of adhesion & communication molecules
physical limitations - less freedom of movement
what are the 6 groups of eukaryotes that complex multicellularity evolved?
brown algae (kelp), green algae, plants, red algae, fungi, animals
why do we believe the 6 groups of eukaryotes evolved more than once?
symbiotic theory, colonial theory, cellularization theory
symbiotic theory
cooperation of different species of unicellular organisms, each with different roles.
colonial theory
cooperation of the same unicellular species as in slime molds
