BIOL 2 Lab #2

• The kingdom Protista contains mostly unicellular eukaryotes
• This taxonomic grouping 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 protest phylogeny are rapidly changing with each new piece of evidence
• The classification suggests 4 “supergroups” within the original Protista kingdom and the taxonomy is still being worked out
• It is important to focus on the characteristics of each clade which explains why they are grouped together
• This lab will only look at the groups that were once included in the Protista kingdom and the other groups (higher plants, fungi, and animals) will be examined in future labs
• Supergroups within the Protista kingdom


  • Excavata
  • SAR
  • Archaeplastida
  • Unikonta
• Clade


  A group of biological taxa (as species) that includes all descendants of one common ancestor
• For the protists, the supergroups are divided into smaller clades assigning them artificial numbers to establish a grouping at a specific level
• General Characteristics and structures of Archaeplastida supergroup


  • Similar DNA sequences and cell structure (The plastids are endosymbiotic cyanobacteria)
• Evidence suggests the Archaeplastida supergroup evolved over a billion years ago with the incorporation of plastids from a cyanobacteria
• Biogeography of Archaeplastida supergroup


  • Contain the red algae, green algae, and the higher plants
• Red Algae


  • General Characteristics and structures - Includes 6000 known species that are reddish in color (pigment: phycoerythrin) which hides the green chlorophyll color. The red pigment allows them to absorb green and blue wavelengths of light. Their life cycle lacks a flagellated stage.
  • Biogeography - The most abundant large algae in the warm coastal waters of tropical oceans.
  • Unique Characteristics - Eaten as “nori”, the wrap around sushi. In the life cycle, the structure most people identify as “algae” is either a structure that is haploid (n) or tetraploid (4n)
• Chlorophytes


  • General Characteristics and structures - Species similar to higher plants in color (pigment: Chlorophyll A and B and carotenoids). Some want to include them in a kingdom with plants called Virdiplantae.
  • Biogeography - Found in marine, freshwater, and terrestrial ecosystems, even in snow.
  • Unique Characteristics - One of two groups commonly called green algae
• Desmids


  • General Characteristics - Unicellular chlorophytes with an isthmus between its two halves. Within the isthmus is the nucleus, and in the two halves are the chloroplasts.
  • Habitat - Common alga found floating in freshwater
• Volvox


  • General Characteristics - 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.
  • Unique Characteristics - Reproduction may occur by binary fission where daughter colonies are formed.
  • Habitat - Freshwater alga found in ponds, ditches, and shallow puddles
• Protococcus


  • General Characteristics - Unicellular or found in small colonies. Often confused with mosses.
  • Habitat - Found as a thin, green covering on the moist, shaded side of trees, rocks, and soil
• General Characteristics of Spirogyra

  • Occurs in multicellular filaments with chloroplasts in ribbon-like strands spiraling through the cells. The nucleus is usually near the center of the cell.
• Cell structure of Spirogyra


  • Ribbon-like strands spiral through the cells
  • Nucleus is usually found near the center of the cell
• Reproduction of Spirogyra


  1. Asexually by fragmentation due to high winds

  2. Sexually through conjugation where two haploid filaments form, male and female gametes combine to form a diploid zygospore, new filaments are produced through meiosis of the zygospore
• Habitat of Spirogyra


  • Found in freshwater ponds
• Example of Spirogyra


  • Ulothrix
• Cell structure of Ulothrix


  • Occurs in multicellular filaments with a single bracelet-like chloroplast in each cell, filaments are haploid
• Reproduction of Ulothrix


  Can reproduce asexually or sexually, sexually through the formation of isogametes, male gamete travels across the conjugation tube to combine with the female gamete and form a diploid zygospore, new filaments are produced through meiosis of the zygospore
• Habitat of Ulothrix


  • Found in freshwater and marine environments, thrives in spring and winter in cool temperatures
• Cell structure of Charophytes


  • Similar to higher plants in color with pigment Chlorophyll A and B and carotenoids, closest relatives of land plants
• Biogeography of Charophytes


  Found in ponds and lakes with ancestors of higher plants living on the edge and subject to occasional drying
• Unique Characteristics of Charophytes


  • Commonly called green algae, share four distinctive traits with higher plants: Rings of cellulose-synthesizing proteins, Peroxisome enzymes, Structure of flagellated sperm, Formation of a phragmoplast
• Cell structure of Unikonta


  • Members include a single flagella or lobed or tube-shaped pseudopodia
• Unikonta might have been the first group of eukaryotes to evolve from other eukaryotes
• Clades of Unikonta


  • Amoebozoans
  • Opisthokonts
• Clade1 of Amoebozoans


  • Slime molds, Gymnamoebas, Entamoebas
• Cell structure of Slime Molds


  • Once thought to be fungi, possess hyphae and fruiting bodies, molecular evidence suggests they are Amoebozoans
• Slime Molds


  • General Characteristics and structures – This clade includes species that were once thought to be fungi because they possess hyphae and their fruiting bodies. Molecular evidence suggests that they are Amoebozoans.
  • Biogeography – The Slime molds include more than 900 species and occur all over the world and feed on microorganisms that live in any type of dead plant material. They contribute to the decomposition of dead vegetation, and feed on bacteria, yeasts, and fungi. For this reason, these organisms are usually found in soil, lawns, and on the forest floor, commonly on decomposing logs.
  • Unique Characteristics – They are divided into two groups distinguished by their unique life cycles: the Plasmodial Slime Molds and the Cellular Slime Molds.
• Plasmodial Slime Molds


  • General Characteristics and structures – They are brightly colored (yellow or orange) and have hyphae that are multinucleated (Coenocytic).
  • Biogeography – These organisms are usually found in soil, lawns, and on the forest floor, commonly on decomposing logs.
  • Unique Characteristics - They form a plasmodium for feeding and reproduction.
• Cellular Slime Molds


  • General Characteristics and structures – They are usually clear and have hyphae that are mono-nucleated (Septate).
  • Biogeography – These organisms are usually crawl through dung, soil, rotting mushrooms, decaying leaves and other organic material.
  • Unique Characteristics - They form a plasmodium during stress and reproduction.
• Gymnamoebas


  • General Characteristics and structures – This clade includes species that have broad pseudopods and usually lack a test.
  • Biogeography – Found in soil, fresh water, and marine environments.
  • Unique Characteristics – The majority are free living heterotrophs but some feed on detritus (non-living organic material).
• Entamoebas


  • General Characteristics and structures – This clade includes amoeba species that are parasitic.
  • Biogeography – Infect all classes of vertebrate animals along with some invertebrates.
  • Unique Characteristics – There are six different species that infect humans. The only species that is known to be pathogenic is Entamoeba histolytica. Infection causes amebic dysentery and is spread from contaminated food and water. It is responsible for up to 100,000 deaths every year.
• Opisthokonts


  • General Characteristics and structures – This clade is a very diverse group. One common characteristic is the flagellate cells, such as most animal sperm and chytrid spores, propel themselves with a single posterior flagellum.
  • Biogeography – Includes four different clades: 1) Nucleariids, 2) the Fungi, 3) the Choanoflagellates and the 4) the Animals.