VL 22

Question 1

Genome verändern sich

Answer 1

Fremde Gene inserieren sich in das Genom

E.coli max 12,8%

Question 2

Recombination

Answer 2

Inversion
Deletion
Transposition

Question 3

Insertion Elements

Answer 3

• Insertion Elements are genetic elements encoding 1-2 Proteins catalyzing their own replication and transposition.

Question 4

Transposons

Answer 4

• Transposons are composite IS Elements with additional co-transposed DNA in between both IS elements.

Prinz: Cut and Paste

Question 5

Changes in Genes and Genomes

Answer 5

Replication errors
Nucleotide damage

Beides führt zu Punktmutationen

Question 6

Changes in Genes and Genomes durch DNA-Aufnahme

Answer 6

Transformation Conjugation Transduction

Sind Invsertionen

Question 7

Horizontal Gene Transfer

Answer 7

Mechanisms
• Natural Competence –> Transformation
• Bacteriophages —>Transduction
• F-Plasmids —> Conjugation

• Transposons / Insertion Elements –>Transposition

Question 8

Transformation

Answer 8

Griffith and Avery Experiments (Maus Experiment )

sieh Folien / Bilder

==> Cells are ready for DNA uptake
- Transformation via heat shock

Question 9

Transformation, Mechanisms

Answer 9

1. dsDNAAttachment
   – DNA Binding
   – Pseudopilus contraction – Peptidoglycan passage
2. dsDNA receptor contact
3. Transfer to Endonuclease
   – Degradation of one strand
4. Transport of residual ssDNA across cytoplasmic membrane
   – ATP-dependent Translocase
5. Synthesis of second strand from ssDNA 6. Recombination with chromosomal DNA

Question 10

Conjugation, F-Pili

Answer 10

directed exchange of DNA
==>Donor cell to Recipient cell
-Conjugation possible between Bacteria and Eukarya

F-Pilus (fertility pilus), makes contact to recipient cell Pilus retraction leads to close cell-cell contact

Question 11

Donor Zell

Answer 11

• F-Plasmid (= F-Factors) = Fertility plasmid with tra-region
• R-Plasmid (= R-Factors) = Resistence plasmid + tra-region

Question 12

Conjugation Mechanisms

Answer 12

1. Attachment of pilus tip
   + Depolymerization of Pilus
2. Stable aggregation complex
   in recipients with LPS + OmpA (no Tra proteins in outer membrane!)
   = “Surface exclusion”
   prevents donor – donor pairing
   TraI
3. Tra Protein binding to oriT
   TraI: single-strand break (=”nick”), protein covalently bound to 5‘-End
   Export complex (Mpf-Proteins) transfers relaxase/ssDNA complex into recipient

Question 13

Conjugation, Summary

Answer 13

Conjugation = directed exchange of DNA
Donor cell Recipient cell

F-Plasmid (fertility plasmid)

• encodes tra Gens for DNA transfer
• Relaxosome catalyses single strand transfer via

F-Pilus
- contacts recipient cell and brings it together with donor

Hfr Strains

• contain episomal copy of F-Plasmid (integrated in Chromosome)
• transfer F-plasmid AND chromosomale DNA

Question 14

Genome

Answer 14

Chromosome+Plasmids

Question 15

Genomes are changable

Answer 15

Genome changes within a cell:

• Mutation
• Inversion
• Deletion
• Transposition

Genome changes from the outside (gene transfer)

• Transformation
• Transduction
• Conjugation