ex 3 lec 2

Exam Logistics

• Paper copy of exam number two available.
• Students encouraged to take the exam promptly as the class will move on to new content.

Previous Material Overview

• Discussion of BRE (Biotechnological Relevance) – A small slide set classification discussing procedures like:
• PCR (Polymerase Chain Reaction)
• Next Generation Sequencing
• Microarrays
• MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time of Flight)
• Emphasized that biotechnology and the technologies used are complex subjects warranting deeper exploration in standalone courses.

Upcoming Content: Prokaryotic Diversity

• Loaded chapter filled with dense information and classifications.
• Students do not need to memorize all species; focus on select interesting examples highlighted by the instructor.
• Recognizing general categories such as:
• Importance in agriculture and environmental cycles (sulfur and nitrogen cycles).

Taxonomic Classification

• Prokaryotes classified based on the sequence of the 16S ribosomal RNA gene, which provides a stable evolutionary marker.
• Classification is dynamic, constantly evolving with new discoveries in microbiology.
• For example, there are currently 24 major phyla in the bacterial domain; focus will be on six, primarily the proteobacteria.

Proteobacteria Overview

• Dominates discussions due to the importance of gram-negative bacteria (largest group).
• Discusses notable classes: alpha, beta, gamma, delta, and epsilon proteobacteria.

Alpha Proteobacteria

• Includes organisms involved in agricultural processes, specifically nitrogen fixation.
• Notable genera:
• Rhizobium – Involved in nitrogen fixation.
• Agrobacterium tumefaciens – Plant pathogen pivotal in creating genetically modified organisms (GMOs).
  • Causes crown gall disease in plants by transferring plasmid DNA to plant cells.
• Caulobacter – Exhibits a unique life cycle with motile and stalked stages.
  • Changes in structure allow adaptation to nutrient-rich environments.

Beta Proteobacteria

• Organisms primarily serve as saprophytes, facilitating the decomposition of organic matter.
• Thiobacillus involved in the sulfur cycle and Nitrosomonas in the nitrogen cycle (oxidizes ammonia to nitrite).
• Neisseria gonorrhoeae causes gonorrhea, a major sexually transmitted infection.

Gamma Proteobacteria

• Key members include:
• Vibrio cholerae (causes cholera).
• Pseudomonas (opportunistic pathogen prevalent in various environments).
  • Notable for its resistance to disinfectants and ability to cause serious infections in immunocompromised individuals.
• Yersinia pestis (causes bubonic plague, historically devastating pandemics).
  • Transmission primarily through fleas but can also become pneumonic.

Delta Proteobacteria

• Focus on Deltaproteobacteria with members that infect other bacteria.
• Existence of bacteria that can infect other bacteria showcases unique ecological interactions.

Epsilon Proteobacteria

• Includes Campylobacter jejuni, which is associated with foodborne illness and potential links to Guillain-Barré syndrome.
• Helicobacter pylori is noted for its role in peptic ulcers and gastric cancer.

Conclusion and Quiz Reminder

• Remaining topics to cover will continue on Wednesday, including a quiz for review.