Microbiology Lecture Notes

Flashcards generated from lecture notes on microbiology, covering topics from the history of microbiology to cell structures and microscopy techniques.

What are the major microbiomes on Earth, and what roles do they play?

Soil, ocean, air, and the human microbiome. They cycle nutrients, support ecosystems, influence climate, and impact health and disease.

How does the human microbiome develop, and what is its importance?

It begins forming at birth through exposure to microbes from the mother and environment. It aids digestion, immune development, and protection against pathogens.

How did the development of the microscope contribute to the understanding of microbes?

It allowed scientists to directly observe microorganisms, confirming their existence and role in disease and biology.

What were the contributions of Hooke, Leeuwenhoek, Pasteur, and Koch to the field of microbiology?

Hooke: Coined the term 'cell' using a microscope. Leeuwenhoek: First observed living microbes. Pasteur: Disproved spontaneous generation; developed germ theory and vaccines. Koch: Developed postulates linking microbes to disease.

What are the key differences between prokaryotic and eukaryotic cells?

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both. Prokaryotes are smaller and simpler.

How are bacteria, archaea, protists, fungi, and viruses different from each other?

Bacteria & Archaea: Prokaryotic; differ in genetics and membrane structure. Protists: Eukaryotic, mostly unicellular. Fungi: Eukaryotic, absorb nutrients, often multicellular. Viruses: Non-cellular, require hosts to reproduce.

What are the major challenges facing microbiology today, and why are they significant?

Antibiotic resistance, emerging diseases, and climate change. They threaten health, ecosystems, and global stability.

How does climate change affect the spread of infectious diseases?

Warmer temperatures expand habitats for vectors (e.g., mosquitoes), increasing disease spread.

What is the role of evolution in understanding microbiology?

It explains microbial diversity, resistance development, and host-pathogen relationships.

What are the basic forms of matter that cannot be broken down by ordinary chemical reactions?

Elements.

What are the six most common elements found in living organisms, and what percentage of cell mass do they make up?

Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur—make up ~96% of cell mass.

Describe the structure of an atom, including the location and charge of protons, neutrons, and electrons.

Protons (+) and neutrons (0): in the nucleus. Electrons (–): orbit the nucleus.

Explain the difference between the atomic number and the mass number of an element.

Atomic number: number of protons. Mass number: protons + neutrons.

What are isotopes, and how do they differ from one another?

Atoms of the same element with different numbers of neutrons.

Describe the arrangement of electrons in shells around the atomic nucleus.

Electrons occupy energy levels/shells around the nucleus; each shell has a max capacity.

What are valence electrons, and why are they important for chemical reactivity?

Electrons in the outermost shell; they determine bonding behavior.

How do ions form, and what are the differences between cations and anions?

Ions form when atoms gain or lose electrons. Cations: positive (lost electrons). Anions: negative (gained electrons).

Why do atoms form chemical bonds?

To achieve stable electron configurations (full outer shells).

How are ionic bonds formed, and give an example of a compound formed by ionic bonds.

By transferring electrons between atoms. Example: NaCl (table salt).

Describe the characteristics of covalent bonds.

Atoms share electrons; stronger and more stable than ionic bonds.

What are organic molecules and hydrocarbons?

Organic molecules contain carbon. Hydrocarbons consist of carbon and hydrogen only.

Explain the difference between polar and nonpolar covalent bonds and provide an example of each.

Polar: unequal sharing (e.g., H₂O). Nonpolar: equal sharing (e.g., O₂).

How do hydrogen bonds form, and why are they important in living organisms?

Between a hydrogen atom and an electronegative atom (like oxygen). They stabilize DNA, proteins, and water properties.

What are chemical reactions, and how do reactants and products relate in a chemical reaction?

Reactants are substances that start a reaction; products are the outcome.

Why is water considered a universal solvent?

Its polarity allows it to dissolve many substances.

What does it mean for a substance to be hydrophilic or hydrophobic?

Hydrophilic: water-attracting. Hydrophobic: water-repelling.

Describe the properties of cohesion and adhesion in water, and why is it important?

Cohesion: water molecules stick to each other. Adhesion: water sticks to other surfaces. Important for capillary action in plants.

How does water contribute to temperature modulation?

Water has high specific heat, resisting temperature changes and stabilizing environments.

How do acids and bases affect the concentration of hydrogen ions in a solution?

Acids increase H⁺. Bases decrease H⁺ (increase OH⁻).

What is the pH scale, and how is it used to measure the acidity or basicity of a solution?

Ranges from 0–14. Below 7 = acidic, 7 = neutral, above 7 = basic.

What are buffers, and how do they help to maintain a stable pH in cells?

Substances that resist pH changes by absorbing or releasing H⁺ ions.

What are the four major classes of organic macromolecules found in living organisms?

Carbohydrates, lipids, proteins, nucleic acids.

What are functional groups, and why are they important in organic molecules?

Groups of atoms that give molecules specific properties (e.g., hydroxyl, carboxyl).

What are carbohydrates, and what are their primary roles in cells?

Sugars that provide energy and structural support.

Describe the structure and function of monosaccharides, disaccharides, and polysaccharides. Provide examples for each.

Monosaccharides: single sugar (glucose). Disaccharides: two sugars (sucrose). Polysaccharides: many sugars (starch, cellulose).

What are lipids, and what are their primary roles in cells?

Nonpolar molecules used for energy storage, insulation, and membranes.

Describe the structure and function of fats, phospholipids, sterols, and waxes.

Fats: energy storage (triglycerides). Phospholipids: membrane structure. Sterols: hormone and membrane stability (cholesterol). Waxes: protective coatings.

What are the primary functions of proteins in cells?

Enzymes, transport, structure, signaling, and defense.

Describe the structure of an amino acid and how amino acids are linked together to form a polypeptide.

Central carbon with amino, carboxyl, hydrogen, and R-group. Linked via peptide bonds.

Explain the different levels of protein structure (primary, secondary, tertiary).

Primary: amino acid sequence. Secondary: alpha helices, beta sheets. Tertiary: 3D folding from interactions between R-groups.

What is protein denaturation, and why is it important?

Loss of structure/function due to heat, pH, etc. Can destroy enzyme activity.

What are nucleic acids, and what are their primary roles in cells?

DNA and RNA store and transmit genetic info.

What are the structural components of a nucleotide?

Sugar, phosphate, nitrogenous base.

How do the structures of DNA and RNA differ?

DNA: double-stranded, deoxyribose, A-T. RNA: single-stranded, ribose, A-U.

What is the structure and function of ATP?

Adenosine triphosphate: stores and transfers energy in cells.

How are the four classes of macromolecules interconnected within the cell?

They work together for structure, function, and regulation: proteins catalyze reactions, nucleic acids store info, carbs fuel activity, and lipids build membranes.

What is binomial nomenclature, and who developed it?

A two-part naming system developed by Linnaeus.

What are the two parts of a scientific name in binomial nomenclature?

Genus and specific epithet.

Why is it important for scientists to use a universal naming system for organisms?

Ensures clear, standardized communication across languages and regions.

What is the main difference between prokaryotic and eukaryotic cells?

Eukaryotes have nuclei and membrane-bound organelles; prokaryotes do not.

What unit is commonly used to measure bacteria? What unit is commonly used to measure viruses?

Bacteria: micrometers (μm); viruses: nanometers (nm).

What is magnification in microscopy, and why is it important?

Increases apparent size of specimens, making details visible.

What is resolution in microscopy, and how does it affect image clarity?

The ability to distinguish two close points as separate; higher resolution = clearer image.

Why is oil immersion used with high-power objective lenses?

Reduces light refraction, improving resolution.

What is the purpose of staining in microscopy?

Enhances contrast to make structures visible.

What is simple staining, and what does it allow you to see?

Uses one dye to show shape and size.

What is negative staining, and when would it be used?

Stains the background; good for visualizing capsules.

What is differential staining?

Uses multiple dyes to distinguish between cell types or structures.

What is the purpose of Gram staining, and what do the results indicate?

Distinguishes Gram-positive (purple) and Gram-negative (pink) bacteria by cell wall type.

What does acid-fast staining detect, and what kinds of organisms does it help identify?

Mycolic acid in cell walls; used for Mycobacterium (e.g., TB).

Why is spore staining used, and what does it reveal?

Highlights endospores, which are resistant cell forms.

What is phase-contrast microscopy, and how does it improve image viewing?

Enhances contrast in transparent samples without staining.

What is dark-field microscopy, and what is it used to observe?

Highlights living, unstained organisms against a dark background.

What is fluorescence microscopy, and how does it work?

Uses UV light to excite fluorescent dyes or proteins in specimens.

What is transmission electron microscopy (TEM), and what kind of cell structures can it reveal?

Shows internal structures in high detail using electron beams.

What is scanning electron microscopy (SEM), and how does it differ from TEM in terms of what it shows?

Reveals 3D surface structures; TEM shows internal details.

What are the key functions of the nucleoid and plasmids in prokaryotic cells?

Nucleoid: contains DNA. Plasmids: extra genetic elements that confer advantages.

How do inclusion bodies and gas vesicles contribute to prokaryotic survival?

Inclusion bodies store nutrients. Gas vesicles regulate buoyancy.

Describe the role of the cytoskeleton in prokaryotic cells.

Maintains shape, assists in division and intracellular transport.

Describe how prokaryotic cells differ from eukaryotic cells in terms of structure and organization.

Prokaryotes lack a nucleus, have simpler structures, and smaller ribosomes.

What roles do surface structures play in the interaction of prokaryotic cells with their environment?

Pili and flagella aid in attachment, motility, and conjugation.

Explain the significance of the cell envelope in protecting prokaryotic cells.

Includes cell wall and membrane; provides structure and defense.

Discuss how the internal structures of prokaryotic cells contribute to their metabolic and reproductive capabilities.

Enzymes and genetic material in the cytoplasm allow rapid metabolism and reproduction without compartments.