bio 1
🧬 Microbiology & Evolution Exam Deck
Section 1 — Methods for Studying Microbes
DNA sequencing | Technological advance that allows scientists to study microbes without growing them in culture.
Microscopy | Method that reveals microbial structure and morphology (what microbes look like).
Culture methods | Method that reveals which microbes can grow under specific laboratory conditions.
Sequencing | Method that reveals genetic identity of microbes and community composition.
Metagenomics | Study of genetic material recovered directly from environmental samples.
Culture-independent methods | Techniques that study microbes without growing them in laboratory cultures.
Why culture methods miss microbes | Many microbes require specific environmental conditions or interactions with other organisms.
Anaerobic microbes | Microbes that live without oxygen and are often missed by traditional culture methods.
Community-dependent microbes | Microbes that require interactions with other microbes to survive.
🌍 Section 2 — Microbes and the Tree of Life
Microbes | Organisms too small to be seen with the naked eye; defined by size rather than evolutionary group.
Three domains of life | Bacteria, Archaea, and Eukarya.
LUCA (Last Universal Common Ancestor) | The common ancestor of all living organisms.
Why LUCA matters | Explains why all life shares core molecular machinery like DNA and ribosomes.
Archaea | Domain of life distinct from bacteria discovered through molecular sequencing.
Discovery of Archaea | Achieved by comparing ribosomal RNA sequences among organisms.
Why Archaea were recognized as a separate domain | Their molecular machinery differed significantly from bacteria.
Viruses | Not included on the tree of life because they lack universal cellular machinery.
⚡ Section 3 — Microbial “Superpowers”
Microbial superpowers | Unique abilities that allow microbes to transform environments and evolve rapidly.
Fermentation | Microbial process that transforms sugars into products like alcohol or lactic acid.
Nitrogen fixation | Conversion of atmospheric nitrogen into biologically usable forms.
Extreme survival | Ability of microbes to live in extreme environments such as hot springs or hydrothermal vents.
Rapid evolution | Microbes evolve quickly due to short generation times and large population sizes.
Microbes as Earth’s engineers | Microbial metabolism drives planetary biochemical cycles.
Why microbes shape ecosystems | They control nutrient cycling, oxygen production, and energy flow.
Microbes and oxygen production | Photosynthetic microbes in oceans produce more than half of Earth’s oxygen.
Pathogens | Disease-causing microbes; represent only about 1% of microbial diversity.
🧫 Section 4 — Human Microbiome
Human microbiome | Community of microbes living in and on the human body.
Holobiont | Host organism plus its associated microbial community.
Microbiome importance | Influences metabolism, immune function, and disease risk.
Variation in human microbiomes | Influenced by genetics, diet, and antibiotic history.
Why microbiome science changed medicine | It challenges single-cause explanations of disease.
Germ-free mice | Animals raised without microbes used to study microbiome effects.
Key finding from germ-free mice | Microbiomes can influence traits like weight gain and immune development.
💊 Section 5 — Antibiotics and Evolution
Antibiotic resistance | Evolutionary process where bacteria survive exposure to antibiotics.
Why antibiotic resistance was predictable | Microbes evolve rapidly and selection favors resistant variants.
Selective pressure | Environmental force that favors survival of certain traits.
Horizontal gene transfer | Movement of genes between organisms without reproduction.
Resistance spillover | Spread of antibiotic resistance between ecosystems (farms, hospitals, environment).
Antibiotic stewardship | Responsible use of antibiotics to slow resistance evolution.
Why antibiotics are strong selective pressures | They target core cellular processes and kill susceptible bacteria efficiently.
Factors increasing resistance evolution | Repeated use, large populations treated, and predictable exposure.
One Health approach | Recognizes connections between human, animal, and environmental health.
🌱 Section 6 — Evolution Concepts
Ladder of progress model | Incorrect idea that evolution moves toward higher or more advanced species.
Correct view of evolution | Evolution produces branching diversity rather than ranked progress.
Contingency in evolution | Outcomes depend on chance historical events.
Cambrian Explosion | Period of rapid diversification of animal body plans.
Factors enabling the Cambrian Explosion | Increased atmospheric oxygen and ecological interactions.
RNA World hypothesis | Early life stage where RNA both stored information and catalyzed reactions.
Natural selection requirements | Heritable variation and differences in survival or reproduction.
🧠Section 7 — Anthropocentrism and Evolution
Anthropocentrism | Viewing humans as the central or most important species.
Problems with anthropocentrism | Leads to hierarchical ranking of species and ethical blind spots.
Human exceptionalism | Belief that humans are fundamentally separate from evolutionary history.
Correct scientific perspective | Humans are unique but not exempt from evolutionary and ecological processes.
Human-centered tests of intelligence | Often underestimate abilities of other species.
🧪 Section 8 — Science and Society
Science as a public good | Knowledge benefits society broadly and should be shared.
Basic research | Fundamental investigation that often leads to future applications.
Pathway from research to societal benefit | Basic research → discoveries → applied technology → societal impact.
Why societies fund science | Knowledge and innovation benefit public health, environment, and technology.