Prokaryotes-07-web - Lecture 3 pg 1 Lecture 3 Prokaryote...

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Lecture 3, pg Lecture 3: Prokaryote Diversity Quick Review: Last lecture, we discussed the tree of life and classification. Part of the discussion centered around the distinction between prokaryotes and eukaryotes. Remember that there are a tremendous number of differences between prokaryotes and eukaryotes. Today our job is to consider biological diversity within prokaryotes. The prokaryotes represent most of the diversity of life. In fact, it is in recognition of the extent of prokaryotic diversity that some scientists use a 3-domain system of classification. I obviously cannot go into too much detail about prokaryote diversity in one day, but it is important to remember that prokaryotes are very diverse. Remember also that there are two major groups of prokaryotes - the eubacteria and the archaea. Much of what I say during this lecture applies to both groups. To avoid confusion, I will be using the terms “prokaryote” and “bacteria” to refer to both the eubacteria and the archaebacteria (also known as archaea). There are several differences between the two groups, but I won’t have time to go into those differences in detail. They are covered, to some extent, in Table 27.2 in your book, and I may have a chance to cover some aspects of that next lecture. Occasionally I may make a specific comment on a difference between eubacteria and archaebacteria, but most of the points I make during the lecture will refer to all prokaryotes. Prokaryotes are the most abundant organisms on earth. Despite their importance, prokaryotes are often ignored, undoubtedly because of their small size. Usually they are invisible to the naked eye, and we’re unaware of their presence. When we are aware of their presence, it is often because they’ve made us ill. Strep throat, diarreah, flu, black plague and gonorreah are all examples of diseases caused by bacterial pathogens. Yet, it is important to note that prokaryotes have a major role in the Earth’s ecosystems; without them higher-life could not persist. Prokaryotes are - Diverse in species - Grow in diverse environments - Extremely Common - Essential – without prokaryotes, many eukaryotes could not survive. - Most are not harmful (that is, most do not cause human disease) Ways to catalog diversity among prokaryotes 1
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Lecture 3, pg Bacterial culture – to be studied, bacteria need to be cultured in the lab. Different bacterial species grow in different cultures, and this aids in the identification of species. This is discussed in some detail in your book. DNA sequence: However, most bacteria cannot be cultured readily in the lab, and
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Prokaryotes-07-web - Lecture 3 pg 1 Lecture 3 Prokaryote...

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