Prokaryote And Extrachromosmal 2 Flashcards
(8 cards)
- Describe how and why prokaryotic cells can differentiate and aggregate to form biofilms and syntrophic consortia
Biofilms form when bacteria aggregate and encase themselves in EPS to survive environmental stress, attach to surfaces, and enhance nutrient access.
Syntrophic consortia occur when different microbial species cooperate metabolically
Describe the specific features of conjugative plasmids (tra/trs genes and oriT) and explain how they drive the processes of conjugation
- tra/trs genes encode proteins required for pilus formation and plasmid transfer.
- oriT is the site where DNA is nicked and transfer begins.
- Conjugation transfers plasmids from donor to recipient, spreading genes like antibiotic resistance.
What are recipient strains ?
Cells lacking a conjugative plasmid
What are donor strains ?
Cells that harbour a conjugative plasmid
Describe the process of conjugation
• Pilus connects donor (F+) to recipient (F-).
• Relaxase nicks DNA at oriT and facilitates transfer of single-stranded DNA.
• Recipient synthesizes complementary strand → becomes F+.
Describe the basic processes of transposition and explain the difference between an Insertion Sequence (IS) and a Transposon (Tn)
Transposition allows DNA segments to move within genomes.
1. IS elements carry only transposase and inverted repeats.
2. Transposons carry additional genes (e.g. antibiotic resistance) and are larger.
Explain how all of the processes above contribute to Horizontal Gene Transmission/Transfer (HGT) between prokaryote cells
- Conjugation spreads plasmids with adaptive traits.
- Transposition enables mobility of genes within/between DNA molecules.
- Biofilms and syntrophy enhance proximity and gene exchange.
What is horizontal gene transfer ?
Allows organisms to acquire new genes from other organisms, bypassing reproduction
