Ameoba

Domains

Domains are the highest level of biological taxonomy. Domains may contain multiple Kingdoms which may each have multiple Phyla and so on.

• Bacteria - Prokaryotes. They are the most widespread domain as well as the most ancient (probably). Very diverse biochemically.
• Archaea - also Prokaryotes but very different from other bacteria. Many of the most extreme thermophiles (high temp) and halophiles (high salt) are Archaea but they also are present in moderate conditions. None are known to cause disease and most are difficult to cultivate in the lab. A very active area of research
• Eukarya - membrane-bounded nucleus and membranous organelles. Includes the four kingdoms Protists, Plants, Animals, Fungi. Eukaryotic cells are usually much larger than the prokaryotic cells.

Bacteria

• Gram Stain - a common stain used to classify bacteria. Bacteria with a thick cell wall (made of peptidoglycan) retain the dye and are gram positive. A gram-negative bacteria probably gave rise to the mitochondria we find in eukaryotic cells.
• Colony morphology - colonies on a petri plate generally grow from a single cell. They vary by shape, texture, color, etc.
• Often classified on shape
  • Spirillum - spiral
  • Bacilli - rod
  • Cocci - round
• Cyanobacteria. These are large (for bacteria) photosynthesizing organisms. A member of this group may have given rise to the chloroplasts in Plant cells. We look at:
  • Gloeocapsa
  • Anabaena

Protists

This Kingdom of Eukarya contains many singled celled organisms as well as some fairly large multicellular organisms. It's a bit of a catch-all group. If it's Eukaryotic and not a fungi, plant, or animal, it's put into the Protists Kingdom.

• Autotrophs are organisms that can make their own food from inorganic sources. Like plants, many Protists are autotrophs via Photosynthesis. We look at:
  • Diatoms
  • Euglena
• Heterotrophs need organic nutrients supplied by other living creatures. Animals and fungi are also heterotrophs. Most protists ingest their food (as do we) but a few absorb nutrients (as do Fungi). Organisms that secrete enzymes extracellularly and absorb the nutrients are called saprophytes (they are Saprotrophic). This means that Protists contain both autotrophs and heterotrophs as well as the special group of heterotrophs called saprophytes. We look at:
  • Amoeba (moves by Pseudopods)
  • Paramecium (cilia)
  • and Trypanosmes (flagella)
• Slime molds - see life cycle fig 14.18. Can be of the Cellular or Plasmodial variety.

Here are some figures from the textbook "Evolution".

• The Tree of Life. This is a phylogenetic tree showing the evolutionary relationships of currently living organisms. A simple tree like this was the only figure in Charles Darwin's "Origin of Species" published in 1865. Here's a different tree.
• A timeline of life on earth, showing origin of various major groups and mass extinctions (red bands). Click to zoom in for more detail.
• Ok, not really from this book, it's the evolution of the tree: primitive and modern.

Practical Review

A study guide before each practical will be sent via email to you from Bio1120's master teacher, Linda Smith-Stanton. Here are the items she thinks you should be familiar with:
• The system of organism classification - remember domains are now the largest categories, then kingdoms...
• General characteristics of Bacteria. Are they uni or multicellular, pro or eukaryotic ...?
• The 3 shapes of bacteria - fig 14.2.
• What cyanobacteria do and how they do it; identification of gleocapsa and/or anabaena. figs 14.3 and 5.
• General characteristics of Protists. Which are heterotrophs and which are autotrophs and what that means their "jobs" can be.
• How to distinguish a photosynthetic protist from a cyanobacterium.
• Be prepared to identify amoeba (fig 14.6a), paramecium (fig 14.6b), trypanosoma (fig 14.6c), diatoms (fig 14.7b) and/or euglena (fig 14.7e).
If these organisms are mobile be familiar with their means of movement (flagella vs cilia vs pseudopods).