Central Dogma & Operons

Central Dogma

·      How is bacterial DNA different from eukaryotic DNA?

 bacterial

-       Plasmids (mobile, genetic info)

-       1 or 2 circular chromosomes (less overall)

-       1 origin of replication

-       Genome is smaller than most eukaryotes

Eukaryotic

-       Linea

-       Listen to video

·      What are plasmids? Why are plasmids important for bacteria?

• Physically separate circular DNAs

• Replicate independently

• Can be transferred between bacteria (mobile)

  •   Can transfer genes to other bacteria (conjugation)

·      How is DNA replication similar between prokaryotes and eukaryotes? How is it different?

• Prokaryotes: Chromosomal DNA is circular; bidirectional; topoisomerase cuts DNA

• Both semiconservative, same bases

·      What are sigma factors? In which step of the central dogma are they essential for bacteria?

• Additional proteins that help initiate transcription.

• Unique to bacteria. Bind to the promoter.

·      Explain where transcription / translation occurs in bacteria. Why is the location of these processes important when thinking about how bacteria perform transcription and translation?

• Same location: cytoplasm because there is no nucleus

• They are coupled (happen at the same time)

Operons

·      What is a constitutive gene? What does it mean if a gene is regulated?

• Constitutive: always expressed; usually encodes proteins that are necessary for survival

• Regulated: expression is turned on and off, influenced by the environment

·      What is an operon? What is the structure of an operon?

• Set of genes controlled by a single promoter

• Structure: promoter (where RNA polymerase binds), operator (repressor protein), genes

·      Why would it be beneficial to the bacteria to organize genes into the same operon?

• Similar functions. Only have to target one promoter area