BIOL 2 Lab #2 Powerpoint

• Kingdom Protista (in the five kingdom system)


  • Contains mostly unicellular eukaryotes
• Protista classification is polyphyletic and based only on cellular structure and life styles not on any molecular evidence
• Scientists are now beginning to see evolutionary history in the protists using molecular biology and detailed comparison of cell structure
• The ongoing changes in the protist phylogeny are rapidly changing with each new piece of evidence
• Four "supergroups" within the original Protista kingdom


  • Excavata
  • SAR
  • Archaeplastida
  • Unikonta
• Classification suggests 4 "supergroups" within the original Protista kingdom and the taxonomy is still being worked out
• Focus on the characteristics of each clade to understand why they are grouped together
• Clade is defined as a group of biological taxa that includes all descendants of one common ancestor
• Cladogram will be used throughout the course to emphasize evolutionary relationships
• Supergroups will be divided into smaller clades assigning them artificial numbers to establish a grouping at a specific level
• Archaeplastida supergroup has similar DNA sequences and cell structure, with plastids being endosymbiotic cyanobacteria
• Archaeplastida supergroup evolved over a billion years ago with the incorporation of plastids from cyanobacteria
• Archaeplastida contain red algae, green algae, and higher plants
• Red algae clade includes 6000 known species that are reddish in color with pigment phycoerythrin
• Red algae are the most abundant large algae in warm coastal waters of tropical oceans
• Red algae are eaten as "nori", the wrap around sushi
• Chlorophytes clade includes species similar to higher plants in color with pigments Chlorophyll A and B and carotenoids
• Chlorophytes are commonly called green algae along with Charophytes
• Desmids are a group of chlorophytes that are usually unicellular with an isthmus between its two halves
• Kingdom with plants


  • Virdiplantae
• Chlorophytes are found in marine, freshwater, and terrestrial ecosystems and are even found in snow
• Chlorophytes


  • They are one of two groups commonly called green algae
• Chlorophytes


  • Usually unicellular with an isthmus between its two halves
• Chlorophytes


  • Within the isthmus, the nucleus is found. In the two halves, chloroplasts are found
• Chlorophytes are a very common alga found floating in freshwater
• Volvox


  • A colonial species consisting of hundreds to thousands of vegetative cells arranged in a single, spherical layer held together by a gelatinous secretion and joined by protoplasmic strands
• Volvox reproduction may occur by binary fission where daughter colonies are formed. It is found in freshwater in ponds, ditches, and shallow puddles
• Protococcus


  • Either unicellular or found in small colonies. Often confused with mosses and found as a thin, green covering on the moist, shaded side of trees, rocks, and soil
• Spirogyra


  • Occur in multicellular filaments with chloroplasts in ribbon-like strands spiraling through the cells. Reproduce asexually or sexually through fragmentation or conjugation
• Spirogyra is found in freshwater ponds
• Ulothrix


  • Occur in multicellular filaments with a single bracelet-like chloroplast in each cell. The filaments are haploid. Developed a holdfast, found in freshwater and marine environments thriving in cool temperatures
• Charophytes are similar to higher plants in color (pigment: Chlorophyll A and B and carotenoids). They are the closest relatives of land plants
• Charophytes are found in ponds and lakes with the ancestors of higher plants living on the edge and subject to occasional drying
• Higher plants


  • Pigment: Chlorophyll A and B and carotenoids
  • Closest relatives of land plants
• Evidence suggests the Unikonta supergroup might have been the first group of eukaryotes to evolve from other eukaryotes
• Amoebozoans have lobe or tube-shaped pseudopodia
• Slime molds were once thought to be fungi because they possess hyphae and their fruiting bodies
• Slime molds contribute to the decomposition of dead vegetation and feed on bacteria, yeasts, and fungi
• Slime molds are usually found in soil, lawns, and on the forest floor, commonly on decomposing logs
• Plasmodial Slime Molds are brightly colored (yellow or orange) and have multinucleated hyphae (Coenocytic)