Julie Robison's List: Astrobiology

• A fungus (plural: fungi) is a kind of living organism: yeasts, moulds and mushrooms are types of fungi. The Fungi are a separate kingdom of living things, different from animals and plants.

• Yeast are complex-celled microorganisms. They are classified as fungi. There are about 1,500 different species of yeast. Most reproduce asexually, by budding. Some use binary fission to reproduce.
• A certain kind of yeast, Saccharomyces cerevisiae has been used for a very long time. It is used for baking bread, for example, or as an additive to help the fermentation of alcoholic drinks, such as beer. It is also considered to be a model organism for modern cell biology.

• An extremophile is an organism that thrives in extreme conditions that are detrimental to most life on Earth. In contrast, organisms from moderate temperature or neutral pH environments may be termed mesophiles or neutrophiles.

• Astrobiology is the study of life in outer space. The field of astrobiology looks for conditions necessary for life, like liquid water, a good temperature, or the presence of oxygen.

   

  Two possible places to find life in the solar system are Europa, a moon of Jupiter and Titan, a moon of Saturn. These places may have liquid water. However, they may be too cold to support life.

• A eukaryote, also spelled eucaryote, is an organism with complex cells, or a single cell with a complex structure. In those cells the genetic material is organized into chromosomes in membrane-bound nuclei.
• In contrast, other organisms, such as bacteria and archaea, do not have nuclei and other complex cell structures. Such organisms are called prokaryotes.

• The Archaea (or Archea) are a group of single-celled organisms. The name comes from Greek αρχαία, "old ones".
• Archaea are tiny, simple organisms. They were originally discovered in extreme environments (extremophiles), but are now thought to be common to more average conditions. Many can survive at very high (over 80 °C) or very low temperatures, or highly salty, acidic or alkaline water.

• A microorganism or microbe is a living thing (organism) that is too small to be visible to the human eye (microscopic). The study of microorganisms is called microbiology. Microorganisms can be bacteria, fungi, archaea or protists.

• Bacteria (one of them is a bacterium) are very small organisms (living things). They are so tiny they can only be seen through a microscope. Bacteria are made up of one cell, so they are a kind of unicellular organism. They are among the simplest single-celled organisms on Earth. They have been living for billions of years. They include a number of extremophiles who live in extreme habitats.
• They vary widely in size and shape, but in general are at least ten times larger than viruses. A typical bacterium is about 1 µm (one micrometer) in diameter, so a thousand bacteria lined up would be one millimeter long. There are about five nonillion (5×10³⁰) bacteria on Earth.^[1]
• Bacteria are identified and grouped by their shapes. The bacilli are rod-shaped, the cocci are ball-shaped and the spirilla are spiral-shaped.

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