Bacterial Genetics Exam One

Lecture 1,

Name several advantages to using bacteria as a genetic model:

• Haploid

• Short Generation Times

• Easy to store, less ethical concerns

• Asexual Reproduction, Allows One to Study Clones

• Easy to Manipulate, Plasmids

By what method do bacteria reproduce?

Binary Fission

Are bacteria typically haploid or diploid?

Haploid

What do you all the daughter cells after a bacteria undergoes asexual reproduction?

Siblings

What are the three main parts of a gene?

1. Promotor/regulatory region (signals for initiation of transcription)

2. Internal region

3. Terminator region

Define: ORF

Open Reading Frame. Encodes for a stretch of amino acids. Begins with ATG/GTG/CTG for the A.A. methionine.

Define: Shine-Dalgarno Sequence

Ribosomal binding site to direct translation.

What is the standard nomenclature for: Gene

• 3 letter designation that relates to function, lower case & italics, then one uppercase letter in italics (i.e. dnaA)

What is the standard nomenclature for: Gene Product

• 4 letter designation matching the gene designation w/ first letter capitalized (i.e. DnaA)

What is the standard nomenclature for: Phenotype

• Short (typically 3) letter names with the first letter capitalized (i.e. Lac^-)

Define: Auxotroph

Strain that cannot make a particular growth factor

What is the standard nomenclature for: Multi-gene pathway

• Single upper case italicized letter designates the specific gene, if gene is unknown a hyphen is used, letters listed in alphabetical order typically (i.e. hisA, hisB, etc.)

What is the standard nomenclature for: mutations

• Mutations are given unique numbers called allele numbers (i.e. lacZ1)

How can one determine if a bacteria’s allele is dominant?

Complementation allows one to observe this. Inserting a plasmid of the WT gene into the mutant, if this restores the WT in the mutant, this indicates the WT is dominant and the mutation is recessive.

Describe the basics of the Griffith’s “Transforming Principal”

Uses two strains: smooth (WT and virulent) and rough (mutant with an altered capsule making it avirulent)

• Smooth → Mouse Died

• Rough → Mouse Lived

• Heat Killed Smooth → Mouse Lived

• Heat Killed Smooth + Rough → Mouse Died

Showed there was some cellular component that can be shared between the bacteria.

How did Avery, McCarty, and MacLeod identify the “transforming principal”

They identified it as DNA. Used DNase to destroy DNA, this prevented virulent S cells. Destroying RNA and protein had no effect on the creation of virulent S cells.

Describe the basics of the Hershey-Chase Experiment:

1. Phages grown with radioactive sulfur to see if proteins are responsible, it was not, only the supernatant was radioactive, showing the proteins were not inserted from the phages to the bacteria

2. Phages grown with radioactive phosphorus to see if DNA is responsible, it was, radioactivity was present in the pellet, showing the DNA was inserted from the phages to the bacteria.