About the final It will be in English. Try to answer in English as well. The problems are given in such a way that very short answers are needed. Chinese allowed if you can only read English People with language difficulty are allowed to have extra time, for example, half an hour, and are allowed to have dictionary. This rule does not apply to general audience in 1-2 weeks online, so that students know wlr A short test in the format of the final will be given they expect Only materials that are mentioned during the lectures will be in the exam. 60 points total
About the final • It will be in English. Try to answer in English as well. The problems are given in such a way that very short answers are needed. Chinese allowed if you can only read English • People with language difficulty are allowed to have extra time, for example, half an hour, and are allowed to have dictionary. This rule does not apply to general audience • A short test in the format of the final will be given in 1-2 weeks online, so that students know what they expect • Only materials that are mentioned during the lectures will be in the exam. 60 points total
Bacterial Genetics
Bacterial Genetics
Three kinds of genetic transfer occur in bacteria Transformation: donor cell releases dNa by lysi S and it is taken up by the recipient cell Conjugation: physical contact between two bacterial cells and transfer of dna Transduction: bacterial virus(phage) transfers the DNa from donor cell to recipient cell
Three kinds of genetic transfer occur in bacteria • Transformation: donor cell releases DNA by lysis and it is taken up by the recipient cell • Conjugation: physical contact between two bacterial cells and transfer of DNA • Transduction: bacterial virus (phage) transfers the DNA from donor cell to recipient cell
Gene Transfer in Bacteria Gene transfer in bacteria Transformation Conjugation Transducti。n ce∥?2 Recipi Lysis of Don。rcel Donor ce∥ Recipient cell don。rcel releases DNA into medium. Donor cell Donor dNa is packaged plasmid in bacteriophage OO C Recipient Donor dna is Lysis of don。 or cell. cell transferred directly to Donor dNa is packaged recipient through in released bacteriophage connecting tube Contact and transfer are promoted by a specialized plasmid Donor dna is in the donor cell Donor dNa is transferred taken up by recipient. when phage particle infects recipient cell
Gene Transfer in Bacteria
Bacterial transformation Transformation involves uptake of DNA, followed by either recombination of the dna with the host chromosome or self-replication of DNA (plasmids). Genes that are close together on DNA can cotransform That is, alleles of both genes can be inserted on the same piece of DNA. Gene order can be determined by cotransformation
Bacterial transformation • Transformation involves uptake of DNA, followed by either recombination of the DNA with the host chromosome or self-replication of DNA (plasmids). • Genes that are close together on DNA can cotransform. That is, alleles of both genes can be inserted on the same piece of DNA. • Gene order can be determined by cotransformation
Natural transformation 力isB hisB trpc trpc Wildtype donor cell trpc/hisB double auxotrophs Recipient cell (b) Competent cell recipient Donor dna Bacterial chromosome (hisB", trpC) Receptor site 1. Donor DNa binds to recipient cell at receptor site 力isB trpc+
Natural Transformation
2. One donor strand is degraded. Admitted donor strand pairs witi homologous region of bacterial chromosome. Replaced strand is degraded One strand degraded 3. Donor strand is integrated into bacterial chromosome hisB trpC 4. After cell replication, one cell is identical to original recipient the other carries the mutant gene. hisB trpc Transformed cell Figure 13.10 Natural transformation in B. subtilis
Transformation of bacterial cells Transformation does not naturally occur in most strains of bacteria, including E. coli E coli and other bacteria can be forced to take up DNA by special chemical and temperature treatments DNA can also be put into bacterial cells by first treating the cells with a brief high voltage pulse (electroporation) This causes a temporary production of pores in the cell membrane, allowing the dNa to pass into the cell
Transformation of bacterial cells • Transformation does not naturally occur in most strains of bacteria, including E. coli. • E. coli and other bacteria can be forced to take up DNA by special chemical and temperature treatments • DNA can also be put into bacterial cells by first treating the cells with a brief high voltage pulse (electroporation). This causes a temporary production of pores in the cell membrane, allowing the DNA to pass into the cell
Bacterial conjugation (a) strain A Mixture of Strain B met bio thrt A and b met+ bio+ thr (b) Cotton plug Medium moved through filter leu+ thi+ leu thi usIng pressure or suctio Strain A Strain B For each sample, wash and plate -10 cells onto Filter minimal medium After incubation cells plated onto minimal medium. No growth met++ bio+ thr* No growth leu+ thi+ cells grow into colonies No growth No growth
The sex factor F DNA transfer is mediated by f, the fertility factor F is a plasmid, a small self-replicating circle of DNA F carries genes that direct the formation of the conjugation tube and its replication and transfer to the recipient The F-factor replicates and a new copy is sent into the F- recipient cell. The F-factor is an example of a conjugative plasmid
The sex factor: F • DNA transfer is mediated by F, the fertility factor. • F is a plasmid, a small self-replicating circle of DNA. • F carries genes that direct the formation of the conjugation tube and its replication and transfer to the recipient • The F-factor replicates and a new copy is sent into the Frecipient cell . The F-factor is an example of a conjugative plasmid