Lesson 2: Microbial Life as the foundation for all life
learning outcomes
By the end of this lesson, students should be able to:
Visualize the microbial world as a network
Discuss the origins of life as an assembly of non-life
Describe some of the ways that viral genomes are varied and multi-faceted
Begin the discuss the nature of viral life
Describe how bacteria have sex and how that may have impacted how mammals have sex
Understand how microbes are a conduit to our own ancestors
Describe how microbial life makes all death productive
Guided drop-in
PREVIOUS questions about lesson 2
What is the difference between positive sense and negative sense RNA?
The idea of ‘sense’ in nucleic acid refers to the nature of its role and what is complementing its sequence.
Negative sense RNA is only a thing with viruses:
Positive sense RNA can be directly translated into proteins (similar to mRNA)
Negative sense RNA is complementary to the viral genome so it has to be converted to positive sense first.
More info in the context of influenza viruses: https://www.virology.ws/2009/05/01/influenza-virus-rna-genome/
Are bacteria affected by oxygen toxicity?
Every living thing is affected by oxygen toxicity, but it’s pretty context dependent and so there are different ways in which bacteria can be damaged by O2. In relation to double-stranded DNA damage, bacteria, in some instances, contain biochemical strategies to repair their own DNA. It’s tricky though, and it doesn’t always work, and when it doesn’t that’s generally lethal to the cell.
DNA double-strand breaks induced by reactive oxygen species promote DNA polymerase IV activity in E.coli: https://www.biorxiv.org/content/10.1101/533422v1
What are the consequences of inheritance of spermal mitochondria, on both an organismic and cellular level for the individual who inherits it, and also for population genetics on both a local and global scale? Is there a "Mitochondrial Adam"?
Paternal inheritance of mitochondrial DNA is a thing in some species, and it’s referred to as ‘paternal leakage’. Whether or not this can occur in human and higher primates is a hotly contested subject – there doesn’t seem to be a consensus as of yet. As such, there’s no research on the effects of this type of heteroplasmy on an individual or population level.
No further evidence for paternal leakage of mitochondrial DNA in humans yet: https://www.pnas.org/content/116/6/1821
More resources on inherited microbes:
https://www.newscientist.com/article/dn26519-composition-of-your-gut-bacteria-may-be-inherited/
https://www.pnas.org/content/112/3/633
https://www.washingtonpost.com/news/speaking-of-science/wp/2015/02/17/bacterial-dna-from-mom-may-be-inherited/
additional resources
Additional resources are posted here for your general interest - the following aren’t integral to the learning but may be supportive. They include music, articles, interviews, writing, and primary scientific literature which you may (or may not) find interesting.
recommended viewing
recommended listening
Bespoken Bones: did you eat your ancestors for breakfast?
Environmental Microbiologist and ancestral animist Siv Watkins discusses the power of our relationships with the smalls, and solving ecological crisis through evolution.
articles and scientific papers
A post from Vincent Racaniello’s excellent blog discussing the benefits of segmented viral genomes
Ten reasons to exclude viruses from the tree of life
Reasons to include viruses in the tree of life
The origin of mitochondria and chloroplasts
You’re Surrounded by Bacteria that are Waiting for You to Die