Microbiology Exam 2 Study Guide: Genetics, Recombinant DNA, Classification, and Eukaryotic Microbes

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Chapter 8: Microbial Genetics

Nucleic Acids and Chromosomes

Microbial genetics focuses on the structure and function of nucleic acids and chromosomes in prokaryotes and eukaryotes.

Nucleic acids are biomolecules (DNA and RNA) that store and transmit genetic information.
Prokaryotic chromosomes are typically circular and found in the nucleoid region, while eukaryotic chromosomes are linear and located in the nucleus.
Plasmids are small, circular DNA molecules found in prokaryotes, often carrying genes for antibiotic resistance.

DNA Replication

DNA replication is the process by which a cell duplicates its DNA before cell division.

Leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments called Okazaki fragments.
Prokaryotic and eukaryotic DNA replication differ in the number of origins of replication and the complexity of the machinery.
Enzymes involved include DNA polymerase, helicase, and ligase.

Transcription and Translation

Transcription is the synthesis of RNA from a DNA template, and translation is the synthesis of proteins from mRNA.

Transcription involves RNA polymerase creating mRNA, tRNA, and rRNA.
Translation uses the genetic code to convert mRNA sequences into amino acids, forming proteins.
Initiation, elongation, and termination are the three main steps in both processes.
Prokaryotes and eukaryotes differ in the location and regulation of these processes.
Codons are three-nucleotide sequences in mRNA that specify amino acids.
Ribosomes are the site of protein synthesis, composed of rRNA and proteins.

Gene Expression and Regulation

Gene expression is controlled by regulatory mechanisms that determine when and how genes are transcribed and translated.

Operons are clusters of genes under the control of a single promoter, common in prokaryotes (e.g., lac operon).
Regulation can be positive (activation) or negative (repression).
Environmental signals can induce or repress gene expression.

Genetic Variation and Transfer

Microbes can exchange genetic material through several mechanisms, increasing genetic diversity.

Transformation: uptake of free DNA from the environment.
Transduction: transfer of DNA via bacteriophages.
Conjugation: direct transfer of DNA between cells via pili.
Transposons: mobile genetic elements that can move within and between genomes.

Chapter 9: Recombinant DNA Technology

Tools and Techniques

Recombinant DNA technology allows scientists to manipulate genetic material for research and biotechnology.

Mutagens, restriction enzymes, reverse transcriptase, synthetic nucleic acids, and gene libraries are key tools.
Vectors (e.g., plasmids, viruses) are used to carry foreign DNA into host cells.
Steps to produce a recombinant vector include cutting DNA with restriction enzymes, ligating DNA fragments, and introducing them into host cells.

PCR and DNA Technology Steps

Polymerase Chain Reaction (PCR) is a technique to amplify DNA sequences.

Three main steps: denaturation, annealing, and extension.
Materials/tools required: template DNA, primers, DNA polymerase, nucleotides.

Methods of DNA Insertion

Natural methods: transformation, transduction, conjugation.
Artificial methods: electroporation, protoplast fusion, microinjection.

Applications of Recombinant DNA Technology

Genomics: study of genomes.
Vaccine production, gene therapy, xenotransplants (transplanting animal organs into humans).
Agriculture: genetically modified crops and livestock.

Chapter 10: Classification

Taxonomy and Domains

Classification organizes living organisms based on shared characteristics.

Taxonomy: science of classifying organisms.
Three domains: Bacteria, Archaea, Eukarya.
Major scientists: Carl Woese (three-domain system), Carolus Linnaeus (binomial nomenclature).

Methods of Classification

Physical, biochemical, serological, and genetic methods are used to identify bacteria.
Examples: Gram staining, metabolic profiling, phage typing, nucleic acid analysis.
Endospores: dormant, resistant structures formed by some bacteria (e.g., Bacillus, Clostridium).

Comparing Domains

Domains differ in cell structure, genetics, and metabolism.

Domain	Cell Type	Cell Wall	Genetic Material
Bacteria	Prokaryotic	Peptidoglycan	Circular DNA
Archaea	Prokaryotic	No peptidoglycan	Circular DNA
Eukarya	Eukaryotic	Varied (cellulose, chitin, none)	Linear DNA

Chapter 12: Eukaryotic Microbes

Major Groups of Eukaryotic Microbes

Eukaryotic microbes include protozoa, fungi, algae, lichens, helminths, and arthropods.

Protozoa: unicellular, motile, cause diseases like malaria.
Fungi: include molds and yeasts; have hyphae and reproduce sexually and asexually.
Algae: photosynthetic, aquatic organisms.
Lichens: symbiotic association between fungi and algae/cyanobacteria.
Helminths: parasitic worms (e.g., platyhelminths, nematodes).
Arthropods: insects and arachnids, some act as disease vectors.

Fungal Sexual Reproduction

Plasmogamy: fusion of haploid donor cell nucleus (+) with recipient cell (-).
Karyogamy: fusion of nuclei.
Meiosis: production of sexual spores.

Transmission and Disease

Dinoflagellates: produce neurotoxins, can cause paralytic shellfish poisoning.
Protozoa: malaria (caused by Plasmodium species).
Helminths: platyhelminths (flatworms), nematodes (roundworms).
Arthropods: mechanical and biological transmission of pathogens by insects.

Characteristics of Eukaryotic Microbes

Motility: flagella, cilia, pseudopodia.
Cell structure: nucleus, organelles.
Distribution: aquatic, terrestrial, parasitic.
Morphology: varied shapes and sizes.
Nutrition: autotrophic (algae), heterotrophic (protozoa, fungi).
Reproduction: sexual and asexual methods.

Additional info:

Equations for DNA replication rate:
Genetic code example:
Operon regulation: