1. Summary

This video focuses on taxonomic classification. It gives some great and clear information on what the three domains are and what distinguishes them from each other. The video uses fun graphics and appropriate language to define these important and potentially confusing terms.

2. Why Watch This Video?

• Have you ever wondered what differentiates the three domains from each other?
• Would you like to know what forms of life could have survived the extreme conditions of the early planet?
• Have you ever been confused by the difference between prokaryotes and eukaryotes?

3. Key Terms

• Extremophile: prokaryotes that thrive in extreme environments such as environments with low or no oxygen, or extreme temperatures.
• Eukaryote: cells or organisms that are distinguished by membrane-bound organelles, a nucleus, and their DNA being stored in the nucleus.
• Prokaryote: cells or organisms that are distinguished by their lack of membrane-bound organelles and nuclei. While they still have DNA it is not stored in the nucleus.

4. Loose Ends

Loose end #1: Bacteria versus Archaea

While the difference between eukaryotes and prokaryotes is explained well in the video, it does not go into much detail about why. Bacteria and archaea are split into two different domains. Upon further reading I learned that archaea were only actually separated into their own domain in the 70s. Up until then they were considered part of the bacteria domain. It was only once we learned more about DNA that we were able to see that archaea are genetically closer to fungi than to bacteria. Learn more

Loose end #2: What is a Protist?

The video explains they can be single or multicellular, hetero or autotrophic, they may have cellulose call walls, some do not. So, what is a protist? The glossary in our learning material for module four defines protists as eukaryotes that are not fungi, plants, or animals. The reading further explains that their grouping is informal. They are placed together less because of what they are, and more because of what they are not.

Loose end #3: Animal or Plant?

Some organisms seem like they could belong to either the animal or plant kingdom. barnacles, sea amenities, sea sponges, Venus fly-traps seem to display characteristics of both. So how do we decide which they should fall into? Well first off plant cells have chloroplasts which they use for photosynthesis. All of these plant looking organisms that fall into the animal kingdom are not able to photosynthesize their own food, they are heterotrophic.

5. Self-Test Questions