The World Within Us: Microbes That Help and Harm | Summary and Q&A

Summary

In this video, Julie Theriot, an associate professor in biochemistry and microbiology, gives a presentation on the microbes that live inside our bodies. She discusses the concept of the world within us, highlighting the importance of microorganisms for our normal functioning, health, and disease. Julie explains the common ancestry of all cells on the planet and how the diversity of microorganisms in the gut differs from the overall bacterial tree.

Questions & Answers

Q: What is the significance of microorganisms that live on our bodies?

Microorganisms are important for our normal functioning, health, and disease. They are more numerous on our bodies than our own human cells, and they play a critical role in various bodily functions, including digestion.

Q: Can you recommend any books on the topic of microbial host interactions?

Yes, I recommend "The Ghost Map" by Stephen Johnson. It tells the story of cholera in 1850s London and explores the interactions between microorganisms and their hosts.

Q: Why are bacteria so important for the world's biodiversity?

Bacteria are the oldest species in terms of evolution, and they are critically important for maintaining the world's biodiversity. If all mammals were wiped out, it wouldn't significantly impact biodiversity. However, if bacteria were eliminated, it would have a devastating effect.

Q: What is Julie Theriot's background and expertise?

Julie Theriot has degrees in physics and biology from MIT and a background in cell biology from UCSF. She has combined physics, computation, and biology in her research and is considered one of the world's leaders in the field of microbiology.

Q: What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells, like bacteria, have their DNA freely floating in the cytoplasm, while eukaryotic cells, like human cells, have their DNA enclosed within a membrane-bound nucleus. Eukaryotic cells also tend to be larger and more morphologically complex than prokaryotic cells.

Q: How can the relatedness of cells be determined using ribosomal RNA?

Ribosomal RNA is a shared component among all cells on the planet. By comparing the sequence of ribosomal RNA, the relatedness of cells can be determined. The more similar the sequences, the more closely related the cells are.

Q: How do bacteria interact with human cells and organisms?

Bacteria interact with human cells and organisms through various mechanisms. They can be beneficial, assisting in digestion and maintaining overall health. However, some bacteria can also cause diseases. The interaction between bacteria and humans is a complex and ongoing area of research.

Q: How much of our body weight is made up of bacteria?

Bacterial cells are very small, and on average, an average bacterial cell in our body is between 1/100 and 1/1000 of the weight of a human cell. Overall, bacteria make up a few percent of our body weight. However, if every cell had an equal vote, bacteria would dominate.

Q: Where is the highest concentration of bacteria in our bodies found?

The highest concentration of bacteria in our bodies is found in the lower intestine, particularly in feces. About 30% of feces is made up of bacteria.

Q: How are bacteria in our gut different from those found elsewhere?

The bacteria found in our gut are different from those found elsewhere. They are a relatively low-diversity subset of the overall bacteria tree. The two dominant classes of bacteria in the gut are Bacteroides and Firmicutes.

Takeaways

Microbes play a crucial role in our bodies, outnumbering our own cells. Bacteria, the oldest species, are essential for maintaining biodiversity. The bacteria in our gut are a specialized subset, co-inhabiting our bodies and aiding in digestion. Understanding microbial host interactions is key to understanding health and disease. The relatedness of all cells on Earth can be traced back to a last universal common ancestor. The diversity and abundance of bacteria in the gut differ from the overall bacterial tree.