Bacteria Genetic Transfer - King Faisal University

College of Medicine, King Faisal University

• The College of Medicine at King Faisal University was established in 1975 (and 1395 AH).

Bacteria Genetic Transfer

• Bacteria Genetic Transfer lecture by Dr. Lorina Badger - Emeka (COM, KFU)

Vision

• To become a model in community engagement through excellence and international recognition in medical education, research, and health care.

Mission

• To promote higher standards in medical education, health care, research, and community health services.

Values

• Islamic values
• Excellence
• Creativity
• Compassion
• Leadership
• Responsiveness to the community

Intended Learning Outcomes 1

• Students should be able to identify and define plasmids, bacteriophages, transposons, and pathogenicity islands.
• Understand the purpose of quorum sensing.
• Describe the role of plasmids, phages, and transposons in gene transfer via conjugation, transformation, and transduction.

Intended Learning Outcomes 2

• Students should comprehend the role of recombination in bacterial gene transfer.

Introduction

• Acquiring genes through genetic transfer provides new genetic information to microorganisms, which can help them survive changing environments.

Importance of Genetic Transfer

• From a clinical perspective, genetic transfer aids in transferring antibiotic resistance genes from resistant bacteria to sensitive ones.
• Plasmids and bacteriophages can add virulence factors (e.g., toxins) to bacteria that previously lacked them.

The Bacterial Gene and Expression

• Bacteria have a single chromosome and may also include extrachromosomal genetic elements like plasmids and bacteriophages (bacterial viruses).
• These elements are independent of the bacterial chromosome and can be transmitted between cells.

Plasmids 1

• Image showing bacterial DNA and plasmids within a bacterial cell.

Plasmids 2

• Plasmids are small genetic elements that replicate independently of the bacterial chromosome.
• They can contribute to genetic change and carry genetic information.

Plasmids 3

• The F plasmid is crucial for conjugation resistance.
• R plasmids carry genes that confer resistance to certain antibiotics.
• These can be transferred through conjugation from one bacterial cell to another.
• Without resistance genes for an antibiotic, a bacterium is susceptible to that antibiotic.

Plasmids Cont'd

• Image showing the replication and integration of plasmids within bacteria.

Bacteriophages 1

• Bacteriophages are bacterial viruses.
• They contain either DNA or RNA genomes, usually protected by a protein shell.
• They can exist outside of host cells and be transmitted between cells.
• Bacteriophages infect bacterial cells.

Bacteriophages 2

• Image describing the transduction process in which a bacteriophage transfers a portion of a donor's DNA to a recipient bacterium.

Bacteria Chromosome

• The bacterial genome comprises genes present on both the chromosomal and extrachromosomal genetic elements.

Pathogenicity Islands

• Genes may form groups called pathogenicity islands.
• Pathogenicity islands share functions or coordinate their control.
• Pathogenicity islands are found in both Gram-negative and Gram-positive bacteria.

Pathogenicity Islands 2

• Some virulence mechanisms are organized into pathogenicity islands.

Quorum Sensing

• Quorum sensing is a process where bacteria produce specific small molecules when a sufficient number (quorum) of bacteria are present.
• This process triggers the activation of virulence and other genes.

Quorum Sensing Examples

• The activation of toxin production and more virulent behavior in Staphylococcus aureus is mediated by increased cyclic peptide concentration.
• Biofilm production in Pseudomonas spp. is triggered by a specific critical concentration of N-acyl homoserine lactone (AHL).

Transposons

• Transposons are transferable genetic elements in the genome.
• Transposons are mobile genetic elements.
• Transposons can move from one position in the genome to another.
• Two main types are replicative and non-replicative transposons.

Transposons 2

• Transposons are pieces of DNA that can move from one location on the chromosome to another.
• They can also move from plasmids to chromosomes or vice-versa, or between plasmids.

Two methods of transposition

• Image showing the cut-and-paste and copy-and-paste mechanisms.

Genetic Transfer

• Transfer of DNA from a donor to a recipient occurs via three mechanisms: transformation, transduction, and conjugation.
• A recombination event is necessary after transfer for genomic changes to be heritable.

Microbial Genetic Transfer between cells

• Image and list describing mechanisms of exchanging genes (Conjugation, transformation, transduction).

Conjugation

• Conjugation occurs between members of the same species.
• The process involves an exchange of genetic information, where DNA is transferred from a donor cell (male) to a recipient cell (female).

Conjugation: Fig

• Image showing the process of bacterial conjugation using a pilus.

Conjugation Cont'd

• Plasmids contain genes that form a bridge (pilus) between bacteria.
• Bacteria with these plasmids are designated F+.
• The plasmid from the F+ bacterium is replicated and transferred to the F- bacterium.

Summary Question 1

• Conjugation is the method of gene transfer involving direct contact between bacteria.

Transformation

• DNA is released from dead or lysed bacteria.
• Other bacteria of the same species take up these fragments.
• The fragments are incorporated into their DNA by recombination.
• Transformation is the process.
• The genetically-transformed cell is called a recombinant cell.

TRANSFORMATION 1

• Image describing the incorporation of foreign DNA into a bacterial cell.

TRANSFORMATION 2

• Image displaying the process of DNA transfer into recipient cell.

Transduction

• DNA is transferred from one bacterium to another using a bacteriophage.

TRANSDUCTI ON cont'd

• Image showing the process of transduction, whereby donor's DNA is integrated into recipient's DNA.

Genetic recombination

• This involves the exchange between two DNA molecules, resulting in new gene combinations.
• The process entails the crossing over of two homologous chromosomes.
• This recombination creates genetic diversity in a population.

High frequency recombinations (Hfr)

• Image showing the Hfr process which exchanges part of the chromosome with the recipient bacterial cell.

Genetic mechanisms of evolution of methicillin- and vancomycin-resistant Staphylococcus aureus (MRSA and MVRSA).

• Image describing the genetic mechanisms involved in the evolution of methicillin and vancomycin-resistant Staphylococcus aureus.

Summary

• Summary of Transformation, Transduction, Conjugation and Transposition showing flow diagrams and images.

References

• Medical Microbiology by Murray, Rosenthal, and Pfaller (7th edition, Chapter 13, pages 125-127).
• Images courtesy of Google. (Various chapters, pages).

This quiz focuses on the concepts of bacteria genetic transfer as taught in the College of Medicine at King Faisal University. Students will explore terms like plasmids, bacteriophages, and transposons, and understand mechanisms such as conjugation, transformation, and transduction. Engage with the content to enhance your knowledge in medical education and microbiology.