Antibiotic Resistance Transfer

Question 1

horizontal gene transfer

Answer 1

• new genetic material is obtained from foreign sources and propogated to the progeny
• could lead to rapid spread of drug resistance
• could be through transformation (direct) or transsduction (indirect)

Question 2

transformation

Answer 2

• competent bacterial cell acquires new genetic material from its environment
• DNA couls come from lysed bacterial cells in the envrionment. These fragments are typically smaller than a chromosome because they are subject to degradation by DNAses in the environemtn

Question 3

competent

Answer 3

• bacteria that have the ability to import DNA

- they have a gene that codes for a specialized DNA uptake apparatus

Question 4

transduction

Answer 4

-a process by which a bacteriophage transfers genetic material from one bacterium to another

Question 5

specialized transduction by lysogenic pahges

Answer 5

• part of the bacterial chromosome adjacent to the attachement site is aberrantly packaged during prophage excision
• phage partices carrying host DNA can subsequently infect another bacterium

Question 6

generalized transduction

Answer 6

• any part of the host chromosome can be transduced by phages
• this happens when infection of a phage causes the dgradation of the host cell genome; little pieces of this degraded genome can be packaged into a new phage and carried to a different host

Question 7

defense mechanisms to prevent newly acquired DNA

Answer 7

• restriction modification system: cuts unmethylated DNA sequences
• CRISPR-Cas System: recognizes and cuts previously seen genetic material
• these are also very important biotech tools
• if the new DNA show homology to the host, it can be integrated through homologous recombination

Question 8

RecA during homologous recombination

Answer 8

-facilitates strand exchange

Question 9

what happens if a new incomng gene is flanked by two homologou regions

Answer 9

• the homologous genes will be inserted with the existing genes leaving a loop where the new gene it
• when the chromosome is replicated, this new gene will be as well and the incorporated into the genome

Question 10

replicons

Answer 10

-DNA elements capable of self replication

Question 11

conjugation

Answer 11

-is a process by which transfer of genetic material from one bact to another through direct contact

Question 12

Rep

Answer 12

replication proteins

Question 13

oriV or oriR

Answer 13

-origin of replication

Question 14

tra operon

Answer 14

a set of genes that encodes the transfer apparatus and other proteins required for conjugation
-can be on a different replicaon

Question 15

oriT

Answer 15

-origin of transfer

Question 16

insertion sequences

Answer 16

• mobile pieces of DNa that encode ONLY the functions involved in transposition
• intracellular only but can move between anything
• encode a single protein, transposase

Question 17

simple or noncomposite transposons

Answer 17

• structurally similar to IS but carry a single drug resistance gene, a transposase, and a resolvase
• must always trasnpose as a unit

Question 18

composite transposons

Answer 18

• a drug resistance gene flanked by two matching IS sequences
• the whole thing can hop as a unit or the ends can move independintly
• two matching Is sequences can move themselves and everything in between

Question 19

integrative and conjugative elements

Answer 19

• combine some of the prooperties of transposons, temperate phages, and conjugal elements all in the same unit
• can not replicate autonomously, need to integrate
• can circularize and excise from the host cell and integrate into a new cell