Micro Lecture Unit 1 Lecture 2

Chapter 1: Introduction

• Core idea: We could not live without the bacteria and archaea that inhabit many body surfaces (including the gut). The microbiome is essential to health.
• Homeostasis: the concept of staying in balance. Not a fixed point, but a normal range for key processes. Things can temporarily go outside the range (e.g., sugar spikes, rapid changes in activity), but staying outside the range for long periods leads to illness.
• When homeostasis is disrupted, it affects multiple systems (not just one): metabolism, oxygenation, blood pressure, etc. Thousands of physiological processes must stay within normal ranges to remain healthy.
• The microbiome helps maintain homeostasis by supporting various body systems (e.g., gut function, barrier against pathogens).
• Mention of E. coli as part of the gut microbiome and its relevance to health and disease in the context of homeostasis.

Chapter 2: Kind Of Stuff

• The digestive tract relies on a healthy microbiome for proper function.
• Microbiome on the skin acts as a barrier, helping prevent invasion by pathogens such as viruses and fungi.
• Earwax (cerumen) has a function in protecting the ear canal from fungal overgrowth; this is an example of microbiome-related protection.
• Concept of symbiosis: microorganisms living in/on us can cause disease in some cases, but most do not cause disease when balanced.
• If the microbiome is out of balance (dysbiosis), negative health effects can occur (e.g., unrealistic or unhealthy dietary choices can disrupt gut balance at any given time).
• Three kinds of symbiotic relationships (briefly noted):
  • Mutualism: both partners benefit.
  • Parasitism: one benefits, the other is harmed.
  • Commensalism: one benefits, the other is unaffected (implicit in the discussion of various microbiome interactions).
• Microbiome acquisition: initial colonization occurs from mothers at birth and through breast milk; changes in childbirth method (C-section, reduced breastfeeding) may affect early microbiome establishment.
• Observational point: in rural communities where kids are exposed to soil, animals, and environments (barefoot, outdoors), health outcomes related to microbiome exposure may differ from more sanitized environments.
• Takeaway: exposure to diverse microbes may build resistance and a robust microbiome; clean environments are not inherently better for microbiome development, and excessive hygiene may delay beneficial microbial exposure.

Chapter 3: Prebiotics And Probiotics

• Question posed: What is the difference between prebiotics and probiotics?
• Probiotics: live bacteria added to the gut to support the existing microbiome (i.e., adding gut bacteria to what you’ve already got).
• Personal practice note: some students take probiotics; the speaker also uses probiotics.
• A practical example given: a probiotic supplement with at least roughly 30,000,000 CFU (colony-forming units) is suggested in the discussion: 30{,}000{,}000 ext{ CFU}
• Parasitism (definition reiterated in this context): a microbe or fungus benefits by harming another living organism.
• Decomposers: organisms that break down dead matter, returning nutrients to the environment; they are crucial for nutrient cycling and the transformation of organic material into inorganic salts usable by plants (i.e., plant nutrient availability).
• Broad statement: bacteria play roles beyond humans and are involved in many biological processes; genetic engineering exists as an established tool, with growing relevance to medicine and life management.
• Future-oriented speculation: in vitro fertilization (IVF) and embryo screening may become common in order to select embryos without certain diseases; this reflects broader debates about genetic engineering, selection, and the ethical implications of “designing” humans.
• Fundamental DNA concept referenced: the bases G, A, T, C (GATC) are the nucleotide bases that constitute genetic material.
• Ethical, philosophical, and practical implications raised: questions about total removal of disease risk in offspring and the social implications of designing or screening embryos.

Chapter 4: Put The Dump

• Real-world relevance: biotechnology and waste management intersect with biology and ethics; these topics are already in practice today.
• Example of biotechnology in medicine: production of human insulin using E. coli. Process overview:
  • Restriction enzymes are used to cut out a DNA fragment that encodes human insulin from a human source (e.g., blood-derived DNA).
  • This insulin gene fragment is spliced into the DNA of E. coli, turning the bacteria into insulin-producing factories.
  • E. coli then produce large quantities of human insulin for medical use.
• Garbage dump analogy: dumps release methane through microbial decomposition; to prevent dangerous buildup or explosions, methane is vented, connecting waste management to chemistry and engineering (e.g., large-scale gas venting systems).
• The dump is not just waste disposal; it involves chemistry, biology, environmental engineering, and policy; understanding these processes is part of the broader field of bioscience and environmental science.
• A practical note: the same microbial processes that decompose waste are part of a broader system that yields useful byproducts, such as methane, which must be managed safely.
• The speaker emphasizes that handling waste properly is a multidisciplinary field combining science and engineering, not merely a housekeeping task.

Chapter 5: Protons And Neutrons

• Fundamental atomic structure:
  • Atoms contain protons and neutrons in the nucleus; electrons orbit around the nucleus.
  • Protons carry a positive charge; neutrons are neutral; electrons carry a negative charge.
  • The total charge of a balanced atom is neutral because the number of protons equals the number of electrons.
  • Neutrons contribute to atomic mass but do not affect charge.
  • Electrons are extremely light and their mass is often considered negligible in basic mass calculations; they occupy space around the nucleus in electron shells/orbitals.
  • The nucleus contains protons and neutrons; electrons orbit the nucleus and are attracted to the positive protons.
  • The general statement that most of an atom is empty space: the nucleus is tiny relative to the overall size, with most of the atom’s volume being empty space occupied by electrons.
• Isotopes and atomic mass:
  • The number of protons (Z) identifies the element (e.g., chlorine has Z = 17).
  • The number of neutrons (N) can vary, changing the atomic mass A = Z + N, while the number of protons (and thus electrons in a neutral atom) remains the same for that element.
  • The neutrons do not affect the identity of the element; they affect the isotope and atomic mass.
• Example: chlorine
  • Protons: 17 ⇒ balanced atom has 17 electrons as well
  • Electron configuration (example for chlorine): 2 in the first shell, 8 in the second shell, and 7 in the third shell, i.e., the electron count per shell is 2, ext{ }8, ext{ }7
  • This configuration reflects a neutral chlorine atom with Z = 17.
• Clarifications about notation and common elements mentioned in the lecture: helium has 2 protons and 2 electrons (and typically a full first shell); some mass examples given relate to common isotopes such as oxygen-16 with 8 protons and 8 neutrons (mass ~ 16).
• Important reminder from the lecture: an accurate mental image of atomic structure is simplified; real atoms have a far more probabilistic distribution of electrons around the nucleus, not fixed orbits as shown in some diagrams.

Chapter 6: Conclusion

• Recap fragment focused on balance and basics of homeostasis, with a nod to sodium and its electron configuration (sodium has 11 protons, and the student is reminded that the two electrons in the first shell and other shell occupancies lead to a stable, balanced state). The discussion emphasizes the broader theme of maintaining homeostasis in the body and the role of chemical and physical processes in sustaining life.
• Note: The chapter ends with an incomplete line about sodium and homeostasis, indicating the discussion would continue to further elaborate how sodium and other ions contribute to maintaining cellular and systemic balance.

Key Formulas and Numerical References

• Atomic mass relation (conceptual): A = Z + N where
  • A = atomic mass, Z = number of protons, N = number of neutrons.
• Protons = Electrons in a balanced (neutral) atom: number of p = e.
• Example electron shell configuration mentioned: for chlorine, 2, 8, 7 in the first, second, and third shells respectively.
• Probiotic dose reference mentioned: 30{,}000{,}000 ext{ CFU} (colony-forming units).
• Note on mass example: reference to oxygen-16 as an example having 8 protons and 8 neutrons (mass ~ 16).