Basics of Microbiology: Growth and genetics

Question 1

Bacterial Transformation definition

Answer 1

Direct uptake DNA from surrounding environment

Question 2

Bacterial Conjugation definition

Answer 2

Transfer from one cell to another via pilus •

Physical contact of two organisms • DNA transferred via plasmids

Question 3

Transduction definition

Answer 3

Transfer of DNA via a bacteriophage

Virus that infects bacteria • Virus picks up DNA, transfers to another bacteria

Question 4

two subtypes of Transduction:

Answer 4

1.)Generalized

Virus infects bacteria • Multiplies, randomly picks up host DNA • Host DNA transferred to other bacteria

2.)Specialized

Transfer of specific genes • Virus DNA inserts into host DNA (lysogeny) • When bacteriophage DNA excised, packaged into virus with specific host DNA

Question 5

Lytic vs. Lysogenic Phages

virulent vs temperate

Answer 5

Lytic cycle

Nuclear material enters bacteria • Multiplies, lyses cell • Releases progeny viruses

Lysogenic cycle

Nuclear material enters cell • Incorporates in host DNA • May later become excised (enter lytic phase) •

Phages that replicate only via the lytic cycle: virulent

Phages that replicate using both: temperate

Question 6

Why Lysogeny Matters: C. diphtheria

Answer 6

Gene for toxin is not part of diptherias genome!

Gene carried by a phage (corynephage), & toxicity depends on infection with phage