L 4-5

Question 1

antigenic drift

Answer 1

accumulation of point mutations
slow
bac and viruses
slow change in the DNA=>new phenotypes

Question 2

antigenic shift

Answer 2

viruses only
different strains in same host=>recombined RNA/DNA and a new virus=>pandemic
fast
change in DNA=>new phenotype

Question 3

antigenic switching

Answer 3

DNA stays the same, but phenotype changes
alterations of gene expression
2 types: phase variation, gene conversion/cassette mech

Question 4

phase variation

Answer 4

type of antigenic switching

genes turned on/off by a recombinase that inverts promoter regions

Question 5

gene conversion/cassette mech

Answer 5

type of antigenic switching
genes moved in and out of expression region
relapsing fever is an example

Question 6

replicon

Answer 6

replicated w/o being in chromosome

Question 7

not replicon

Answer 7

must be incorporated into chromosome for replication

Question 8

types of recombination

Answer 8

homologous: replaces similar gene in chromosome, requires rec proteins
non homologous: random insertion, no rec proteins

Question 9

Conjugation

Answer 9

one-way transfer of DNA
gram(-) use pili
gram (+) use pheromones
T4SS secretory system

Question 10

high frequency recombination

Answer 10

plasmid joins chrom. by non homologous recomb before conjugation making chrom able to transfer
usually doesn’t work
transfers half plasmid then chrom then other half
takes ~100 min

Question 11

Integron

Answer 11

sequence with an ATT1 site where promotor-less genes can use integrase to jump into the DNA line and get transcribed

Question 12

Composite transposon

Answer 12

Jumping genes

genes within a cell switch around with help of transposase