Microbiology Exam 1 Study Guide: Chapters 1–6

Chapter 1: Foundations of Microbiology

Scientific Contributions and Historical Figures

This section covers the foundational scientists and their impact on microbiology.

• Antonie van Leeuwenhoek: First to observe and describe microorganisms using a microscope.

• Louis c

• Robert Koch: Established Koch's postulates, linking specific microbes to specific diseases.

• Other contributors: Lister (antiseptic surgery), Semmelweis (handwashing), Jenner (smallpox vaccine), Koch, Nightingale (nursing and hygiene).

Koch's Postulates: Criteria to establish a causative relationship between a microbe and a disease.

• Microorganism must be found in all cases of the disease.

• It must be isolated and grown in pure culture.

• It must cause the disease when introduced into a healthy host.

• It must be re-isolated from the experimentally infected host.

Scientific Method: Systematic approach to research involving observation, hypothesis, experimentation, and conclusion.

Spontaneous Generation: The disproven idea that life arises from non-living matter. Pasteur's swan-neck flask experiment provided evidence against this theory.

Prokaryotic vs. Eukaryotic Organisms:

• Prokaryotes: No nucleus, simple cell structure (e.g., Bacteria and Archaea).

• Eukaryotes: Nucleus present, complex organelles (e.g., Fungi, Protozoa, Algae).

Contributions of Robert Koch: Developed techniques for pure culture, identified causative agents of tuberculosis and anthrax.

Chapter 2: Chemical Foundations of Microbiology

pH Scale and Nucleic Acids

This section introduces the chemical basis of life, focusing on pH and nucleic acids.

• pH Scale: Measures acidity or alkalinity; ranges from 0 (acidic) to 14 (basic), with 7 as neutral.

• Nucleotides: Building blocks of nucleic acids, composed of a sugar, phosphate group, and nitrogenous base.

• Nitrogenous Bases: Adenine, Thymine, Cytosine, Guanine, and Uracil (in RNA).

• Classes of Nucleic Acids:

  • DNA (Deoxyribonucleic Acid): Stores genetic information.

  • RNA (Ribonucleic Acid): Involved in protein synthesis and gene regulation.

Chapter 3: Cell Structure and Function

Cellular Processes and Structures

This chapter explores the structure and function of prokaryotic and eukaryotic cells.

• Major Processes: Transport, metabolism, and reproduction in living cells.

• Cell Walls: Prokaryotic (peptidoglycan in bacteria) vs. eukaryotic (cellulose in plants, chitin in fungi).

• Glycocalyces: Protective outer layers; include capsules and slime layers.

• Fimbriae and Pili: Surface structures for attachment and genetic exchange.

• Flagella: Structures for motility; arrangement and structure differ between bacteria and eukaryotes.

• Gram Stain: Differentiates bacteria into Gram-positive (thick peptidoglycan) and Gram-negative (thin peptidoglycan, outer membrane).

• Acid-Fast Bacteria: Have waxy cell walls (e.g., Mycobacterium).

• Ribosomes: Sites of protein synthesis; 70S in prokaryotes, 80S in eukaryotes.

• Endosymbiotic Theory: Eukaryotic organelles (mitochondria, chloroplasts) originated from prokaryotic cells.

Feature	Prokaryotes	Eukaryotes
Nucleus	Absent	Present
Cell Wall	Peptidoglycan (bacteria)	Cellulose/chitin (some)
Ribosomes	70S	80S
Organelles	Absent	Present

Chapter 4: Microbial Classification and Identification

Staining and Taxonomy

This chapter discusses methods for classifying and identifying microorganisms.

• Staining Techniques: Gram, acid-fast, and endospore stains differentiate bacteria based on cell wall properties.

• Binomial Nomenclature: System of naming organisms using genus and species (e.g., Escherichia coli).

• Three Domains: Bacteria, Archaea, Eukarya (proposed by Carl Woese).

• Identification Methods: Microscopy, staining, biochemical tests, molecular techniques.

Chapter 5: Microbial Metabolism

Energy, Enzymes, and Metabolic Pathways

This section covers how microorganisms obtain and use energy.

• Metabolism: Sum of all chemical reactions in a cell, including catabolism (breakdown) and anabolism (synthesis).

• ATP Phosphorylation: Substrate-level, oxidative, and photophosphorylation are mechanisms for ATP production.

• Enzymes: Biological catalysts that speed up reactions; have active sites for substrate binding.

• Enzyme Inhibition: Competitive (inhibitor binds active site) and noncompetitive (inhibitor binds elsewhere).

• Glycolysis, Krebs Cycle, Electron Transport Chain: Central metabolic pathways for energy production.

• Fermentation: Anaerobic process producing ATP and byproducts like lactic acid or ethanol.

• Photosynthesis: Conversion of light energy to chemical energy in photoautotrophs.

Equation for Cellular Respiration:

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP$

Chapter 6: Microbial Growth and Nutrition

Growth Requirements and Measurement

This chapter examines how microbes grow, their nutritional needs, and how growth is measured.

• Categories by Carbon and Energy Source:

  • Photoautotrophs: Use light and CO2.

  • Chemoautotrophs: Use inorganic chemicals and CO2.

  • Photoheterotrophs: Use light and organic compounds.

  • Chemoheterotrophs: Use organic compounds for both energy and carbon.

• Oxygen Requirements: Obligate aerobes, obligate anaerobes, facultative anaerobes, aerotolerant anaerobes, microaerophiles.

• Biofilms: Communities of microorganisms attached to surfaces; formed via quorum sensing.

• Streak Plate Method: Technique to isolate pure bacterial colonies.

• Culture Media: Nutrient agar, selective, differential, enriched, and minimal media.

• Binary Fission: Asexual reproduction in bacteria.

• Bacterial Growth Curve: Lag, log, stationary, and death phases.

• Measuring Growth: Direct methods (plate counts, microscopy) and indirect methods (turbidity).

Growth Phase	Description
Lag	Adaptation, no division
Log (Exponential)	Rapid cell division
Stationary	Growth rate equals death rate
Death	Cells die faster than they divide

Nitrogen Fixation: Conversion of atmospheric nitrogen (N2) to ammonia (NH3), essential for biosynthesis in many organisms.

Additional info: For each chapter, review the critical thinking questions and chapter summaries in your textbook for deeper understanding and exam preparation.