Microbio Exam 3

What tools are commonly used in genetic engineering and recombinant DNA technology?

Restriction enzymes, DNA ligase, plasmids/vectors, PCR, reverse transcriptase, gel electrophoresis, cloning hosts, CRISPR-Cas9, and blotting techniques.

What is PCR?

Polymerase Chain Reaction; a technique used to amplify specific DNA sequences.

What is Reverse Transcriptase (RT)?

An RNA-dependent DNA polymerase that synthesizes DNA from an RNA template.

What is cDNA?

Complementary DNA made from mRNA using reverse transcriptase.

What is gel electrophoresis used for?

Separating DNA fragments based on size.

What is a vector?

A DNA molecule used to carry foreign DNA into a host cell.

What are restriction enzymes?

Enzymes that cut DNA at specific recognition sequences.

What is blotting?

A technique used to transfer DNA, RNA, or proteins onto a membrane for analysis.

What is recombinant DNA?

DNA formed by combining genetic material from different sources.

What enzyme joins DNA fragments together?

DNA ligase.

What is the purpose of a genomic library?

To store the entire genome of an organism as cloned DNA fragments.

What is metagenomics?

The study of genetic material recovered directly from environmental samples.

Why is metagenomics important?

It identifies microbes that cannot be cultured in the lab.

What is autonomous replication?

Self-replication of DNA independent of the chromosome.

Give examples of autonomously replicating DNA.

Plasmids and some viral genomes.

What is the significance of the Ti plasmid?

It transfers genes into plant cells and is used in plant genetic engineering.

What types of genes are commonly found on plasmids?

Antibiotic resistance, virulence, metabolic, and conjugation genes.

How are plasmids exchanged between bacteria?

Horizontal Gene Transfer (HGT), especially conjugation.

What is protoplast fusion?

Fusion of cells whose cell walls have been removed.

What is electroporation?

Using electrical pulses to create temporary pores in cell membranes for DNA entry.

Name one therapeutic product produced by biotechnology.

Human insulin.

What is gene silencing?

Turning off gene expression.

What is CRISPR-Cas9 used for?

Precise genome editing.

What is whole-genome shotgun sequencing?

Sequencing random DNA fragments and assembling them computationally.

What is genomics?

The study of an organism's complete genome.

What are the three major areas of genomics?

Structural, functional, and comparative genomics.

What is bioinformatics?

The use of computers and statistics to analyze biological data.

What sciences are combined in bioinformatics?

Biology, computer science, mathematics, and statistics.

What does in silico mean?

Computer-based analysis.

What is genome annotation?

Identifying genes and their functions within DNA sequences.

What is functional genomics?

Study of gene functions and interactions.

What is proteomics?

Study of all proteins produced by a cell or organism.

What is a DNA microarray?

A tool used to measure expression levels of many genes simultaneously.

What samples are commonly analyzed with DNA microarrays?

mRNA converted to labeled cDNA.

What is comparative genomics?

Comparing genomes between organisms.

What is two-dimensional gel electrophoresis used for?

Separating proteins by charge and size.

What is the human microbiome?

The collection of microorganisms living in and on the human body.

What is bioprospecting?

Searching nature for useful biological products.

What is high-throughput screening (HTS)?

Rapid testing of thousands of compounds for biological activity.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

How do viruses differ from all living organisms?

They are acellular and require a host for replication.

What are methanogens?

Archaea that produce methane.

What are methanotrophs?

Microbes that consume methane.

Name three anaerobic habitats of methanogens.

Swamps, sediments, and animal digestive tracts.

Name two groups of Archaea.

Methanogens and extremophiles.

What role do microbes play in biogeochemical cycles?

They recycle carbon, nitrogen, sulfur, and phosphorus.

What is the overall goal of sewage treatment?

Reduce organic matter and BOD before release.

What does BOD stand for?

Biological Oxygen Demand.

Why must sewage be treated before release?

To prevent oxygen depletion and environmental damage.

What are the three stages of sewage treatment?

Primary, secondary, and tertiary treatment.

Which stage removes most BOD?

Secondary treatment.

What role do microbes play in sewage treatment?

They degrade organic waste.

What is anaerobic sludge digestion?

Microbial decomposition of sludge without oxygen.

Where is methane produced during sewage treatment?

Anaerobic digesters.

What is methane from sewage used for?

Energy production.

What is composting?

Controlled microbial decomposition of organic matter.

What is bioremediation?

Using microbes to remove pollutants.

What are the three basic principles of antimicrobial therapy?

1. Selective toxicity - to exploit differences in structure and

metabolism of pathogens and host cells (to kill organisms not man)

2. Reach the site of infection at inhibitory concentrations

3. Penetrate and bind to target, avoiding inactivation and extrusion

Why do some microbes produce antibiotics?

To compete against other microorganisms.

What are chemotherapeutic agents?

Chemicals used to treat disease.

What are four major antimicrobial targets?

Cell wall, protein synthesis, nucleic acid synthesis, and metabolism.

How do sulfa drugs work?

Inhibit folic acid synthesis.

How does trimethoprim work?

Blocks a later step in folic acid synthesis.

Which antibiotic inhibits DNA replication?

Quinolones (e.g., ciprofloxacin).

Which antibiotic inhibits RNA transcription?

Rifampin.

What is a beta-lactam ring?

The active ring structure found in penicillins and cephalosporins.

Which antibiotics contain beta-lactam rings?

Penicillins and cephalosporins.

What do penicillin, cephalosporin, bacitracin, and vancomycin have in common?

They inhibit bacterial cell wall synthesis.

What is beta-lactamase?

An enzyme that destroys beta-lactam antibiotics.

What is selective toxicity?

Ability to harm microbes while sparing host cells.

What is therapeutic dose?

Amount needed to produce a therapeutic effect.

What is therapeutic index?

Ratio of toxic dose to effective dose.

How do bacteria become resistant?

Mutation, enzyme production, target modification, efflux pumps, reduced permeability.

How can resistance spread?

Conjugation, transduction, and transformation.

What are R-plasmids?

Plasmids carrying antibiotic resistance genes.

Why are superbugs increasing?

Antibiotic misuse and overuse.

What does Tamiflu inhibit?

Neuraminidase.

What does Amantadine inhibit?

Viral uncoating.

How do polyenes work?

Bind ergosterol and disrupt fungal membranes.

How do azoles work?

Inhibit ergosterol synthesis.

What does chloroquine treat?

Malaria.

What does isoniazid treat?

Tuberculosis.

What does amphotericin B treat?

Fungal infections.

What does acyclovir treat?

Herpesvirus infections.

Why are there fewer antiviral drugs than antibacterial drugs?

Viruses use host cell machinery, making selective targeting difficult.

How do RT inhibitors work?

Block reverse transcriptase.

How do protease inhibitors work?

Prevent viral maturation.

How do aminoglycosides work?

Cause misreading of mRNA at the 30S ribosomal subunit.

How does tetracycline work?

Blocks tRNA attachment to the 30S ribosome.

How do macrolides work?

Inhibit translocation at the 50S ribosome.

How does chloramphenicol work?

Inhibits peptidyl transferase activity at the 50S ribosome.

What is the Kirby-Bauer test?

Disk diffusion test used to determine antibiotic sensitivity.

What is an E-test?

Determines the Minimum Inhibitory Concentration (MIC).

What is MIC?

Lowest concentration of drug that prevents visible growth.

What does submicroscopic mean?

Too small to be seen with a light microscope.

What does obligate intracellular parasite mean?

Must replicate inside living host cells.

What are the two components every virus must have?

Nucleic acid and a capsid.

What are the steps of viral replication?

Attachment → Entry → Uncoating → Synthesis → Assembly → Release.

Why is uncoating important?

It releases the viral genome for replication.

What is a Cytopathic Effect (CPE)?

Visible damage to infected cells.