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Biology Study Guide Complete review of your notes • Vocabulary + concepts to know • No tables This guide covers the vocabulary, nitrogen cycle, phosphorus cycle, water cycle, energy transfer, food chains, organisms, and ecological processes from all your notes. I combined repeated information and clarified a few definitions to help you prepare for tomorrow’s test. Part 1: Vocabulary 1. Ecology and ecosystem organization Ecology — The study of interactions between organisms and their environment. Biosphere — All parts of Earth where life exists. Population — Members of the same species living in the same area. Community — Different populations living and interacting in the same area. Ecosystem — A community of organisms and the nonliving environment they interact with. Biomass — The total mass of living organisms in a particular area or trophic level. Trophic level — An organism’s feeding position in a food chain. 2. Types of organisms Autotroph — An organism that makes its own food using light energy or chemical energy. * Examples: plants, algae and some bacteria. * Autotrophs are also called producers. Heterotroph — An organism that obtains energy and nutrients by consuming or absorbing organic matter from other organisms. - Examples: animals and fungi. Producer — An organism that makes its own organic food. Consumer — An organism that obtains energy by eating other organisms. Herbivore — An organism that eats plants or other producers. Examples: deer, cows and caterpillars. Carnivore — An organism that eats other animals. Examples: lions, hawks and sharks. Omnivore — An organism that eats both plants and animals. Examples: humans, bears and crows. Scavenger — An organism that feeds on dead animals. Example: a vulture. Detritivore — A heterotroph that obtains nutrients by ingesting detritus. Detritus — Dead and decomposing plant and animal material, including organic waste. Decomposer — An organism that breaks down organic matter externally using enzymes and absorbs the released nutrients. - Examples: fungi, mushrooms and bacteria. Phytoplankton — Tiny photosynthetic organisms, including algae, that drift in aquatic environments and form the base of many aquatic food webs. 3. Food and energy vocabulary Food chain — A single pathway showing how energy passes from one organism to another. Food web — A network of interconnected food chains showing feeding relationships in an ecosystem. Energy transfer — The movement of energy from one organism to another. Photosynthesis — The process that uses light energy to make sugars from carbon dioxide and water. Cellular respiration — The process of breaking down molecules such as glucose to release usable energy. Chemosynthesis — The process of using energy from chemical reactions to make organic molecules. 4. Nitrogen cycle vocabulary Nitrogen fixation — The conversion of atmospheric nitrogen gas into usable nitrogen compounds. Assimilation — The process in which plants absorb nitrogen compounds and use the nitrogen to build organic molecules. Consumption — Animals obtain nitrogen and other nutrients by eating plants or other animals. Ammonification — Decomposers convert nitrogen in organic matter into ammonia or ammonium. Nitrification — Bacteria convert ammonium into nitrite and then nitrate. Denitrification — Bacteria convert nitrate into nitrogen gas, returning nitrogen to the atmosphere. Ammonia — A nitrogen-containing compound with the formula . Ammonium — A positively charged nitrogen ion with the formula . Nitrite — A nitrogen-containing ion with the formula . Nitrate — A nitrogen-containing ion with the formula , which plants can absorb. 5. Water cycle vocabulary Evaporation — Liquid water absorbs energy and changes into water vapor. Condensation — Water vapor cools and changes into liquid droplets. Transpiration — The release of water vapor from plants, mainly through their leaves. Precipitation — Water falling from clouds as rain, snow, sleet or hail. 6. Nutrients and other vocabulary Phosphorus — An essential nutrient used to build DNA, RNA, ATP and cell membranes. It also supports plant growth and root development. Limiting nutrient — A nutrient whose limited availability restricts the growth of organisms. Eutrophication — The process in which excess nutrients enter a body of water, promoting excessive algae growth and potentially reducing dissolved oxygen. Amino acids — The building blocks of proteins. Proteins — Molecules made of amino acids that perform many functions in living organisms. Nucleic acids — Molecules such as DNA and RNA that store and transmit genetic information. External digestion — The breakdown of food outside an organism’s cells or body using enzymes, as fungi do. Decomposition — The breakdown of dead organic matter and waste, returning nutrients to the environment. Part 2: Things You Need to Know 1. The nitrogen cycle The nitrogen cycle describes how nitrogen moves between the atmosphere, soil, water and living organisms. Nitrogen is essential for making proteins, amino acids and nucleic acids such as DNA and RNA. Although the atmosphere contains a lot of nitrogen gas, most plants cannot use atmospheric nitrogen gas directly. The main processes 1. Nitrogen fixation Atmospheric nitrogen gas () is converted into usable nitrogen compounds. * Mainly carried out by nitrogen-fixing bacteria. * Lightning also helps convert atmospheric nitrogen into compounds that enter the soil. 2. Assimilation Plants absorb nitrate () or ammonium () from the soil and use the nitrogen to make proteins and nucleic acids. 3. Consumption Animals obtain nitrogen by eating plants or other animals. 4. Ammonification Decomposers break down nitrogen-containing material in dead organisms and waste, releasing ammonia or ammonium into the environment. 5. Nitrification Bacteria convert ammonium into nitrite and then nitrate. NH_4^+ \rightarrow NO_2^- \rightarrow NO_3^- 6. Denitrification Bacteria convert nitrate into nitrogen gas, returning nitrogen to the atmosphere. Important things to remember * Nitrogen fixation starts with atmospheric nitrogen gas, . * Nitrogen fixation is carried out mainly by bacteria, but lightning also contributes. * Plants need nitrogen to build proteins and nucleic acids. * Animals obtain nitrogen through food. * Decomposers recycle nitrogen from dead organisms and waste. * Nitrification produces nitrite and then nitrate. * Denitrification returns nitrogen to the atmosphere. The nitrogen cycle is a cycle, so nitrogen can enter through several pathways. The processes do not always occur in one simple sequence. 2. Nitrogen formulas to memorize * = nitrogen gas * = ammonia * = ammonium * = nitrite * = nitrate Pay special attention to the difference between ammonia, ammonium, nitrite and nitrate. 3. The phosphorus cycle Phosphorus is an essential nutrient that organisms need to survive. How it moves through the environment * Weathering breaks down rocks and releases phosphorus into soil and water. * Plants absorb phosphorus through their roots. * Animals obtain phosphorus by eating plants or other animals. * Waste and dead organisms are broken down by decomposers. * Phosphorus returns to soil and water, where it can be used again. Why phosphorus matters * It is needed to build DNA and RNA. * It is part of ATP, which cells use to transfer energy. * It is a component of cell membranes. * It helps plants grow and develop strong roots. * It is often a limiting nutrient in soils and aquatic ecosystems. Important difference: Unlike the nitrogen cycle, the phosphorus cycle does not have a major atmospheric gas phase. 4. Eutrophication Eutrophication happens when too many nutrients enter a body of water. This can occur when fertilizers or sewage enter lakes and rivers. Know the steps: * Excess nutrients enter the water. * Algae grow rapidly, creating an algal bloom. * Algae die and decomposers break down the dead material. * Decomposers use dissolved oxygen during decomposition. * Oxygen levels decrease, which can harm or kill fish and other aquatic organisms. Remember that the problem is not simply that algae grow. The decomposition of dead algae can use up the oxygen aquatic organisms need. 5. The water cycle The water cycle describes how water moves between Earth’s surface and the atmosphere. The four main processes * Evaporation: Liquid water absorbs heat and becomes water vapor. * Condensation: Water vapor cools and forms liquid droplets, helping create clouds. * Precipitation: Water falls from clouds as rain, snow, sleet or hail. * Transpiration: Plants release water vapor through their leaves. Water also collects in rivers, lakes and oceans, while some infiltrates the soil and becomes groundwater. Make sure you can explain the difference between evaporation and condensation: * Evaporation: liquid to gas. * Condensation: gas to liquid. 6. Photosynthesis, respiration and chemosynthesis Photosynthesis * Uses light energy to produce sugars. * Takes in carbon dioxide and water. * Releases oxygen in typical plant photosynthesis. * Stores energy in chemical bonds. Cellular respiration * Breaks down glucose and other molecules to release usable energy. * Happens in plants, animals and many other organisms. * Most of the energy organisms obtain is eventually released as heat. Chemosynthesis * Uses energy from chemical reactions instead of sunlight. * Allows certain organisms, such as some bacteria, to produce organic molecules. How they differ Photosynthesis uses light energy, cellular respiration releases usable energy from molecules, and chemosynthesis uses chemical energy to make organic molecules. 7. Carbon and energy in ecosystems Your notes include these important ideas about carbon and energy. * Carbon enters the atmosphere through processes such as respiration, decomposition and the burning of fossil fuels. * Vehicles release carbon dioxide when they burn gasoline or other fossil fuels. * Plants remove carbon dioxide from the atmosphere during photosynthesis. * Energy moves through food chains and food webs. * Most energy obtained by organisms is eventually released as heat. * Unlike nutrients, energy does not continuously recycle through an ecosystem; it flows through the ecosystem. 8. Food chains and food webs A food chain shows one pathway of energy transfer, while a food web shows many connected feeding relationships. For example: Grass — Producer Grasshopper — Primary consumer Frog — Secondary consumer Snake — Tertiary consumer Arrows point from the organism being eaten to the organism receiving the energy. Know these facts * Producers make their own food. * Primary consumers eat producers. * Secondary consumers eat primary consumers. * Tertiary consumers eat secondary consumers. * Food webs connect multiple food chains. * Less energy is available at higher trophic levels because energy is used for life processes and much is released as heat. 9. Autotrophs versus heterotrophs Autotrophs: * Make their own organic food. * Use light energy or chemical energy. * Include plants, algae and certain bacteria. Heterotrophs: * Obtain organic food from other organisms or organic matter. * Include animals and fungi. * Depend directly or indirectly on producers for energy. Remember that not every heterotroph eats another living organism. Decomposers, for example, absorb nutrients from dead organic matter. 10. Detritivores, decomposers and scavengers These three types of organisms are easy to confuse. Scavengers eat dead animals. Examples include vultures and some crabs. Detritivores ingest dead organic matter and waste. Examples include earthworms, woodlice and some aquatic organisms. Decomposers break down organic matter externally by releasing enzymes, then absorb the nutrients. Examples include fungi and bacteria. Where they live * Terrestrial means land-based. Examples of detritivores include earthworms and woodlice. * Aquatic means water-based. Some crabs and other aquatic organisms feed on detritus. Why they matter They help recycle nutrients back into the environment, allowing those nutrients to be used by other organisms. 11. Ecosystem organization Know the difference between these four terms: * Population: One species living in a particular area. * Community: Multiple populations living in an area. * Ecosystem: The community and its nonliving environment. * Biosphere: All parts of Earth where life exists. A community consists of different populations. An ecosystem includes both living and nonliving components. 12. Phosphorus transfer through food webs * Plants absorb phosphorus from soil or water. * Heterotrophs obtain phosphorus by eating plants or other animals. * Phosphorus moves between organisms through feeding. * Decomposition and waste return phosphorus to the environment. Phosphorus is important for plant growth and for building molecules that all living organisms need. Part 3: What to memorize before the test If you’re short on time, make sure you can answer these questions without looking at your notes. Final review checklist 0 of 13 Define ecology, biosphere, population, community and biomass. Explain the differences between autotrophs and heterotrophs. Distinguish herbivores, carnivores, omnivores, scavengers, detritivores and decomposers. Explain the nitrogen cycle processes and put them in context. Memorize N₂, NH₃, NH₄⁺, NO₂⁻ and NO₃⁻. Explain the phosphorus cycle and why phosphorus matters. Explain the steps of eutrophication and why oxygen decreases. Define evaporation, condensation, precipitation and transpiration. Compare photosynthesis, cellular respiration and chemosynthesis. Explain the difference between food chains and food webs. Explain why energy decreases at higher trophic levels. Explain how decomposers recycle nutrients. Describe how carbon enters and leaves the atmosphere. My advice for tonight: Study the vocabulary first, draw the nitrogen cycle from memory, and then explain eutrophication and the water cycle out loud. Finish by testing yourself on the checklist. If you can explain each item without looking, you’re in a good position for your test.

🦠 MICROBIOLOGY — WEEK 1 STUDY NOTES Microbiology Foundations Assigned reading: 1.1 What Our Ancestors Knew 1.2 A Systematic Approach 1.3 Types of Microorganisms 3.1 Spontaneous Generation 3.2 Foundations of Modern Cell Theor/y 1.1 What Our Ancestors Knew First: What is microbiology? Microbiology = the study of very small organisms and infectious agents. Microorganism / microbe = an organism that is generally too small to see without a microscope. Examples include: * Bacteria * Archaea * Fungi such as yeast and molds * Protozoa * Microscopic algae * Some parasites Viruses are also studied in microbiology, although viruses are acellular, meaning they are not made of cells. Important idea Microbes are NOT automatically bad. Many microbes are harmless or helpful. They: * help produce food * live naturally in and on our bodies * help ecosystems function * can be used to make medicines and other products Only some microbes cause disease. 🍞 Humans Used Microbes Before They Knew Microbes Existed Humans were using microorganisms for thousands of years before microscopes existed. One of the biggest examples is: Fermentation Fermentation = microorganisms change sugars/carbohydrates into substances such as: * alcohol * gases * organic acids Microbes involved can include: bacteria + yeast + molds Humans used fermentation to make: * bread * cheese * yogurt * beer * wine * pickled vegetables Easy example Yeast eats/metabolizes carbohydrates in bread dough. ↓ Yeast produces carbon dioxide (CO₂). ↓ Gas becomes trapped in the dough. ↓ Bread rises. Remember Fermentation = microbes changing sugars. ⸻ 🧊 Ötzi the Iceman Ötzi was a preserved human mummy approximately 5,300 years old. Scientists found evidence that he had: * Trichuris trichiura → a parasitic worm * Borrelia burgdorferi → bacterium that causes Lyme disease He also carried a fungus called Fomitopsis betulinus, which has laxative and antibiotic properties. Why does this matter? It shows that ancient people were trying to treat disease long before they understood microorganisms. ⸻ 🦠 Early Ideas About Disease Before microscopes, people didn’t know exactly what caused disease. Some cultures believed disease came from: * supernatural forces * angry gods * fate * bad air But some people began to realize that disease might spread between people. ⸻ Quarantine Ancient societies sometimes separated sick people from healthy people. This is called: Quarantine = separating potentially infected people to prevent disease spread. Even though they didn’t know what bacteria or viruses were, they understood that some diseases could spread. ⸻ 🚿 Sanitation Ancient civilizations also developed ways to improve sanitation. Examples included: * clean-water systems * drainage systems * sewers * aqueducts This was important because removing human waste and providing cleaner water can reduce disease transmission. ⸻ Important People From Early Medicine Hippocrates Who? Greek physician. Important idea: Disease had natural causes, rather than always being caused by supernatural forces. He is commonly called: “Father of Western Medicine.” Remember Hippocrates → disease has natural causes. ⸻ Thucydides Thucydides survived the Athenian plague. He noticed that people who survived the disease usually did not become sick from the same disease again while caring for infected people. This was an early observation of: Immunity Immunity = the body’s ability to resist a particular infection/disease. Remember Thucydides → early idea of immunity. ⸻ Marcus Terentius Varro Varro proposed that extremely tiny creatures that could not be seen might cause disease. He described tiny creatures entering the body through the: * mouth * nose This was an important idea because microscopes did not yet exist. Remember Varro → invisible tiny creatures may cause disease. ⸻ Ibn Sina / Avicenna Ibn Sina wrote the important medical work: Canon of Medicine He described ideas involving: * contagion * spread of disease * transmission through breath * isolation of sick people His work contributed to ideas that later became important for quarantine and infectious-disease control. ⸻ 🔬 Birth of Microbiology The development of the microscope completely changed science. For the first time, scientists could actually see microorganisms. ⸻ Antonie van Leeuwenhoek Extremely important name. In 1675, Antonie van Leeuwenhoek used powerful simple microscopes to observe tiny organisms. He called them: “animalcules” Today we know that some of the organisms he observed were: * bacteria * protists Remember Leeuwenhoek → first to describe bacteria/microorganisms seen through a microscope. Think: Leeuwenhoek = LOOKED at microbes. ⸻ ⭐ Golden Age of Microbiology Approximately: 1857–1914 During this period, scientists made major discoveries connecting microorganisms with: * fermentation * disease * medicine * infection Two huge names: Louis Pasteur and Robert Koch You are going to see both names repeatedly in microbiology. ⸻ Louis Pasteur Pasteur showed that microorganisms are responsible for fermentation. He also developed: Pasteurization Pasteurization = using controlled heat to kill/reduce microorganisms that cause spoilage or disease. He also worked on vaccines, including a vaccine against: rabies Pasteur will become especially important again in Section 3.1. Remember Pasteur → fermentation → pasteurization → vaccines → helped prove germ theory → disproved spontaneous generation ⸻ Robert Koch Koch showed that particular microbes could cause particular diseases. He identified microorganisms associated with diseases including: * anthrax * tuberculosis * cholera Remember Koch → specific microbe → specific disease. ⸻ 🧪 Basic Microbiology Laboratory Tools You don’t need to master these yet, but recognize the terms. Microscope → magnifies microbes. Stains/dyes → add color/contrast so microorganisms are easier to see. Growth media → nutrients/material used to grow microorganisms in the laboratory. Petri dish → shallow dish commonly used to hold growth media. Test tube → can contain liquid or solid/semi-solid growth media. Bunsen burner → flame that can be used during laboratory sterilization procedures. These will make much more sense once you start doing microbiology lab work. ⸻ 1.2 A Systematic Approach Now we move from discovering microbes to: “How do scientists organize and name all these different organisms?” ⸻ Taxonomy Definition Taxonomy = classification, description, identification, and naming of living organisms. Think: Taxonomy = biological organization system. ⸻ Carolus Linnaeus Linnaeus developed an important system for classifying organisms. The main levels used in classification include: Kingdom → Phylum → Class → Order → Family → Genus → Species A common memory trick: K P C O F G S King Philip Came Over For Good Soup You should know the order. ⸻ Species Species is the most specific/basic taxonomic level in this hierarchy. Example: Homo sapiens Homo = genus sapiens = species ⸻ Binomial Nomenclature Very important term. Binomial = two names. Every organism receives a scientific name consisting of: Genus + species Example: Homo sapiens Rules: Genus * first letter CAPITALIZED species * lowercase Both should normally be italicized when typed. Correct: Homo sapiens Not: Homo Sapiens ❌ homo sapiens ❌ Homo Sapiens ❌ ⸻ 🌳 Phylogeny Phylogeny = evolutionary relationship/history between organisms. Scientists can represent these relationships with a: Phylogenetic tree A phylogenetic tree shows how organisms are believed to be evolutionarily related. Organisms with a more recent common ancestor are considered more closely related. ⸻ Classification Changed Over Time Scientific classification did not stay the same. Linnaeus Originally divided nature into kingdoms including: * animals * plants * minerals The mineral kingdom was later abandoned. ⸻ Ernst Haeckel Added: Protista for many unicellular organisms. He later proposed Monera for organisms lacking nuclei. Remember: Haeckel → Protista ⸻ Robert Whittaker Developed a five-kingdom system: Animalia Plantae Fungi Protista Monera ⸻ 🧬 Carl Woese — VERY IMPORTANT Carl Woese used differences in: ribosomal RNA (rRNA) to study evolutionary relationships. His work helped establish the modern: THREE-DOMAIN SYSTEM 🟠 Bacteria 🟣 Archaea 🔵 Eukarya This is very important for your Week 1 material. Memorize: BAE Bacteria Archaea Eukarya ⸻ Bergey’s Manuals These are important references used in bacteriology. They help scientists: * classify bacteria * identify bacteria You probably don’t need every detail yet, but recognize the name: Bergey’s Manual ⸻ How Can Bacteria Be Identified? Scientists can identify microorganisms using things such as: Biochemical tests Look at chemical/metabolic characteristics. DNA/RNA analysis Examines genetic material. Serological tests Use reactions involving antibodies/antigens. ⸻ 1.3 Types of Microorganisms This section is VERY IMPORTANT. You need to understand the major groups. ⸻ 🌎 Three Domains of Life Again: 1. Bacteria 2. Archaea 3. Eukarya ⸻ Before We Continue: Two Big Cell Types You will hear these words constantly: PROKARYOTE vs EUKARYOTE Prokaryotic cells DO NOT have a membrane-bound nucleus. Bacteria = prokaryotic Archaea = prokaryotic Eukaryotic cells DO have a membrane-bound nucleus. Examples include: * animals * plants * fungi * protozoa * algae Super important: Prokaryote = NO nucleus Eukaryote = HAS nucleus ⸻ 🦠 BACTERIA Bacteria are: * unicellular * prokaryotic * found almost everywhere Some bacteria are helpful. Some bacteria can cause disease. Many bacteria have cell walls. You’ll learn much more about bacterial structures later. ⸻ 🌋 ARCHAEA Archaea are also: * unicellular * prokaryotic Like bacteria, they do not have a nucleus. BUT: Archaea ≠ Bacteria They differ in: * genetics * evolutionary history * metabolic pathways * cell membrane composition * cell wall composition Archaea occur in many environments. Important textbook point No archaea have been identified as human pathogens. Remember Bacteria + Archaea = Prokaryotes ⸻ 🔵 EUKARYA Eukaryotic microorganisms include: Algae Protozoa Fungi Helminths These have eukaryotic cells. ⸻ 🌿 ALGAE Algae can be: * unicellular * multicellular They are similar to plants in an important way: They perform photosynthesis. Photosynthesis = using light energy to make chemical energy/food. Remember: Algae → photosynthesis. ⸻ 🧫 PROTOZOA Protozoa are: * unicellular * eukaryotic * structurally more complex than bacteria Many are capable of movement. Remember Protozoa → single-celled eukaryotes, often motile. Motile = able to move. ⸻ 🍄 FUNGI Fungi studied in microbiology include: Yeasts Usually unicellular. Molds Usually grow as multicellular filament-like structures. Examples of fungi can be microscopic even though other fungi, such as mushrooms, are large. Remember Fungi → yeast + molds ⸻ 🪱 HELMINTHS Helminths = parasitic worms. You may think: “A worm isn’t microscopic. Why is it in microbiology?” Good question. Adult worms may be large enough to see. BUT their: * eggs * larvae can be microscopic. Therefore they are studied in microbiology. ⸻ 🦠 VIRUSES Viruses are different from cellular organisms. Viruses are ACELLULAR. Acellular = not made of cells. Viruses cannot reproduce independently. They require a: Host cell to reproduce. Remember Virus = acellular + requires host to reproduce ⸻ ⭐ Major Microorganism Comparison Group Cell type Nucleus? Important idea Bacteria Prokaryotic ❌ Some cause disease Archaea Prokaryotic ❌ Different from bacteria; no known human pathogens Fungi Eukaryotic ✅ Yeasts + molds Protozoa Eukaryotic ✅ Unicellular, often motile Algae Eukaryotic ✅ Photosynthesis Helminths Eukaryotic ✅ Parasitic worms Viruses Acellular No cell Need host to reproduce 🔥 This table is worth knowing very well. ⸻ 3.1 Spontaneous Generation This is mainly about one historical question: Where does life come from? People once believed: Spontaneous Generation Spontaneous generation = the belief that living organisms can arise from nonliving material. Examples people once believed: rotting meat → maggots mud → frogs old food → microorganisms Today we know this idea is incorrect. ⸻ Francesco Redi Redi tested whether maggots appeared spontaneously from meat. He compared meat that flies could reach with meat protected from flies. Result Maggots appeared when flies could access the meat. This suggested: Maggots came from flies — not directly from the meat. Remember Redi → meat + flies + maggots ⸻ John Needham Needham performed experiments with broth. He boiled broth and then observed microbial growth afterward. He interpreted this as evidence supporting: Spontaneous generation. Remember Needham → supported spontaneous generation. ⸻ Lazzaro Spallanzani Spallanzani disagreed. He boiled broth for longer and sealed the containers more carefully. The sealed broth did not show microbial growth. He argued that microbes came from contamination from the environment rather than being generated spontaneously. Remember Spallanzani → argued against spontaneous generation. ⸻ 🦢 Louis Pasteur’s Swan-Neck Flask Experiment This is VERY IMPORTANT. Pasteur used flasks with long curved necks. Why the curved neck? Air could enter the flask. BUT: Dust and microorganisms became trapped in the curved neck. So the broth remained uncontaminated. When microorganisms could reach the broth, microbial growth occurred. Conclusion Microorganisms did NOT spontaneously appear. They came from microorganisms already present in the environment. Pasteur helped establish the principle: “Life comes from life.” Exam memory Pasteur → swan-neck flask → disproved spontaneous generation. ⸻ 3.2 Foundations of Modern Cell Theory Now we move from: “Where do microbes come from?” to: “What is life made of?” Answer: CELLS ⸻ 🧬 Cell Theory The textbook describes the development of the idea that cells are the fundamental units of life. The central ideas are: 1. All living organisms are made of one or more cells. 2. The cell is the fundamental/basic unit of life. 3. Cells arise from pre-existing cells. Think: Life → cells → cells come from cells. ⸻ Robert Hooke In the 1660s, Robert Hooke examined cork with a microscope. He saw tiny compartments and called them: “cells” Remember Hooke → named/described cells. Don’t mix him up with Leeuwenhoek: Hooke → cells Leeuwenhoek → microorganisms ⸻ Matthias Schleiden Schleiden studied plants. He concluded that: Plants are made of cells. Remember: Schleiden → plants ⸻ Theodor Schwann Schwann studied animals. He concluded: Animals are made of cells. Remember: Schwann → animals ⸻ Robert Remak Remak provided evidence that cells form through the division of existing cells. ⸻ Rudolf Virchow Virchow strongly promoted the idea: Cells come from other cells. So: New cells do not spontaneously appear. ⸻ Easy Scientist Memory Hooke → saw/named cells Schleiden → plants Schwann → animals Remak/Virchow → cells come from existing cells ⸻ 🧬 Endosymbiotic Theory This sounds difficult, but the basic idea is simple. Endosymbiotic theory says: Mitochondria and chloroplasts were originally bacteria-like prokaryotic cells. A larger ancestral cell engulfed them. Instead of being destroyed, the cells developed a mutually beneficial relationship. Eventually, the engulfed bacteria evolved into: Mitochondria and Chloroplasts inside eukaryotic cells. ⸻ Evidence for Endosymbiotic Theory Mitochondria and chloroplasts have similarities to bacteria. They have: Their own DNA Their DNA resembles bacterial DNA. Their own ribosomes Their ribosomes resemble bacterial ribosomes. They reproduce through a process similar to binary fission Binary fission is a major way bacteria reproduce. Easy version Mitochondria and chloroplasts act strangely like bacteria because their ancestors were bacteria. ⸻ Lynn Margulis Lynn Margulis helped develop and promote the modern endosymbiotic theory. Remember Margulis → endosymbiotic theory ⸻ 🦠 Miasma Theory vs Germ Theory This distinction is very important. Miasma Theory Old idea: Disease comes from “bad air” associated with rotting material. Think: Bad smell → disease. This theory was eventually replaced. ⸻ Germ Theory Germ theory = many diseases are caused by microorganisms. Think: Microbe enters/infects body → disease Scientists whose work helped establish germ theory included: * Ignaz Semmelweis * John Snow * Louis Pasteur * Joseph Lister * Robert Koch ⸻ 🧼 Ignaz Semmelweis Semmelweis worked around childbirth. He noticed that patients treated by doctors and medical students had much higher rates of puerperal fever than patients cared for by midwives. Medical students often went from: autopsies → examining living patients without washing their hands. Semmelweis introduced handwashing with chlorinated lime solution. Result Maternal deaths fell dramatically. Remember Semmelweis → HANDWASHING ⸻ 💧 John Snow John Snow investigated cholera outbreaks in London. He connected cholera cases with: contaminated water. His work helped show that disease wasn’t simply coming from “bad air.” He is important in the history of: Epidemiology Epidemiology = study of disease patterns and spread in populations. Remember Snow → cholera + contaminated water + epidemiology ⸻ Joseph Lister Lister applied ideas about microorganisms to surgery. He promoted: * handwashing * cleanliness * sterilization * antiseptic techniques He used carbolic acid (phenol) to reduce infections during surgery. Result Surgical infections decreased. Remember Lister → antiseptic surgery ⸻ Robert Koch — Again Koch developed: Koch’s postulates These helped scientists determine whether a particular microorganism causes a particular disease. Basic idea: specific microorganism → specific disease You will learn Koch’s postulates in more detail later. ⸻ 🔥 WEEK 1 — PEOPLE YOU NEED TO KNOW Scientist/person Remember THIS Hippocrates Disease has natural causes Thucydides Early observation of immunity Varro Invisible creatures may cause disease Leeuwenhoek Observed microbes/bacteria Linnaeus Taxonomy + naming organisms Haeckel Added Protista Whittaker Five kingdoms Woese Three domains; used rRNA Redi Meat + flies + maggots Needham Supported spontaneous generation Spallanzani Evidence against spontaneous generation Pasteur Swan-neck flask; fermentation; germ theory Hooke Described/named cells Schleiden Plants are made of cells Schwann Animals are made of cells Remak/Virchow Cells come from cells Margulis Endosymbiotic theory Semmelweis Handwashing John Snow Cholera + contaminated water Lister Antiseptic surgery Koch Specific microbes cause specific diseases ⸻ 🚨 THE 15 THINGS I WOULD MEMORIZE FIRST Don’t try to memorize every paragraph tonight. Start here: 1. Microbiology = study of microorganisms. 2. Fermentation uses microbes to convert sugars into products such as alcohol, gases, or acids. 3. Leeuwenhoek observed microorganisms. 4. Pasteur and Koch were major scientists during the Golden Age of Microbiology. 5. Taxonomy = classification and naming of organisms. 6. Binomial nomenclature = Genus + species. 7. Three domains = Bacteria, Archaea, Eukarya. 8. Bacteria + Archaea = prokaryotes. 9. Prokaryote = no membrane-bound nucleus. 10. Eukaryote = has membrane-bound nucleus. 11. Virus = acellular and needs a host to reproduce. 12. Spontaneous generation = life arises from nonliving matter. 13. Pasteur’s swan-neck flask helped disprove spontaneous generation. 14. Cell theory = organisms are made of cells, cells are the basic unit of life, and cells come from existing cells. 15. Germ theory = microorganisms can cause disease. ⸻ 🧠 Super-Simple Week 1 Mental Map Think about the entire week’s reading as one story: PART 1 — Humans discover microbes People used microbes before knowing they existed. ↓ Leeuwenhoek sees them. ↓ Scientists begin studying them. ⸻ PART 2 — Scientists organize microbes Linnaeus → Taxonomy ↓ Woese → 3 domains ↓ Bacteria | Archaea | Eukarya ⸻ PART 3 — Scientists ask where life comes from People believed in spontaneous generation. ↓ Redi + Spallanzani question it. ↓ Pasteur disproves it. ↓ Life comes from existing life. ⸻ PART 4 — Scientists understand cells Hooke → cells ↓ Schleiden → plants Schwann → animals ↓ Remak/Virchow → cells come from cells ↓ Cell Theory ⸻ PART 5 — Scientists understand disease Old: Miasma = bad air causes disease ❌ ↓ New: Germ theory = microorganisms can cause disease ✅ ↓ Semmelweis → handwashing Snow → contaminated water Lister → antiseptic surgery Pasteur → microbes Koch → specific microbe causes specific disease