Bacterial Genetics

Question 1

What is a genotype? phenotype?

Answer 1

genetic makeup of organism; expression of genes

Question 2

What is a mutation? silent mutation?

Answer 2

heritable change in genetic material usually other than incorporation of foreign genetic material; no effect on phenotype

Question 3

What is the difference between homologous and non-homologous recombination?

Answer 3

transferred DNA has high homology to recipient

Question 4

What is transfection?

Answer 4

similar to transformation, except recipient cells are bacterial protoplasts or spheroplasts or eukaryotic cells with no cell walls

Question 5

What is conjugation?

Answer 5

exchange of genetic material between 2 bacterial strains, requires cell to cell contact via sex pilus (TFSS) so F+ and recipient is F-

Question 6

What is the F factor?

Answer 6

fertility factor, codes for sex pilis in extra chromosomal DNA one of many types of plasmids

Question 7

What is a plasmid?

Answer 7

any extra chromosomal circular DNA elements capable of existing independently of bacterial chromosome

Question 8

What is HFR?

Answer 8

a cell in which F factor has integrated into bacterial chromosome, can function as male or donor, High Frequency Recombination

Question 9

what is an insertion sequence?

Answer 9

a simple mobile genetic element consisting of a transposase gene flanked by two inverted repeats

Question 10

What is a transposon?

Answer 10

a block of genetic elements which can be transferred from one position to another within or between bacterial chromosomes or plasmids

Question 11

What is a resistance transfer factor?

Answer 11

RTF; transmissible (by conjugation) plasmid which codes for resistance of antimicrobial agents

Question 12

What factors are responsible for emergence and spread of antibiotic resistance

Answer 12

mutations, exchange of genetic information, increase selective pressures (hospital, miss-use, easy access, veterinary)

Question 13

What are pathogenicity islands?

Answer 13

gene clusters that code for virulence factors

Question 14

What is transduction?

Answer 14

transfer of bacterial genetic information from one cell to another by a virus

Question 15

What is a virus?

Answer 15

obligate intracellular parasite containing only one kind of nucleic acid

Question 16

What is a bacteriophage? Components

Answer 16

a bacterial virus; capsid- outer protein coat which surrounds nucleic acid and capsomere- one of the protein subunit which makes up the capsid

Question 17

What are the phases of the lytic cycle?

Answer 17

absorption of phage to specific receptor site, penetration of phage tail through cell wall and discharge of phage DNA, intracellular development (replication and synthesis), maturation (formation of mature phage), and lysis

Question 18

What is the definition of a virulent phage?

Answer 18

phage that reproduces by the lytic cycle

Question 19

What is the lysogenic cycle?

Answer 19

stable association (integration) of phage chromosome with bacterial chromosome

Question 20

What is a temperate phage?

Answer 20

phage capable of lysogeny

Question 21

What is a lysogenic bacterium?

Answer 21

bacterial cell which is lysogenized

Question 22

What is a prophage?

Answer 22

DNA of temperate phage which is integrated into bacterial chromosome

Question 23

What is phage or lysogenic conversion?

Answer 23

change in phenotype of bacterial cell die to influence of temperate phage genes

Question 24

What is a transducing phage?

Answer 24

a phage carrying part of bacterial DNA

Question 25

What is generalized transduction?

Answer 25

phages can carry any random segment of host chromosome (usually no phage DNA)

Question 26

What is specialized transduction?

Answer 26

only specific regions of chromosome located near prophage attachment site are transduced (some host and some phage)