Prokaryotic Stuff

There are many ways to regulate the expression of a gene 

  • Transcriptional control

  • Translation control

  • Post-translational control 



Prokaryotic genes that have similar functions are going to be organized into operons

  • Define what an operon: a continuous strand of mRNA

    • There is a single promoter for the entire operon which allows multiple proteins to be made 



Transcription and Translation of prokaryotic polycistronic mRNAs

  • THe initiaitino for prokaryotes occurs at any shine dalgarno sequence and can be polycistronic which means that one strand of mRNA can code for several polypeptides




The lac operon

  • We the lac l gene

  • The lac z gen

  • The lacl promoter

  • Lac y gene

  • The operator

  • The lac operon promoter

  • crp-cAMp binding site 



The b-galactosidase enzyme, will catalyze the hydrolysis of lactose

  • Breaks down lactose into galactose and glucose







There is a negative control of the lac Operon



Negative control: when the repressor of the operon is present, the operon will not be expressed













How can a mutation change gene expression

  • This was part of your class activity where we had to figure out different ways to express the gene 



Partial diploids help distinguish the effect of different haplotypes

  • Particle diploids cells contain two different copies of the lac operon and two copies of the lacl gene

Plasmids are used to create these partial diploids

  • Additional dna can be added to bactierla if we were to indtrouce a circular pieces of DNA known as the plasmid 





Cis & Trans Elemenets

  • Trans-acting elements are able to diffuse through the cytoplasm to perform their function (lacl)

  • Cis-acting elements are fixed sequence of DNA that only affect adjacent genes



Positive Control of the Lac Operon

-Positive Control: Operon expression increase in the presence of an activator

A positive control for this would be when in the presence of lacrosse which functions to remove the repressor that would latch onto the operator




Catabolites of this metabolic process?




Catabolite repression

  • Glucose metabolism is favored over lactose

  • The level of glucose in the cell inversely correlates with the level of cAMP

  • Cap (cataboite activator protein) is a positive regulator which only work after binding campa

    • Is a catabolite activator protein,c






  • cAMP is synthesize even when glucose levels are low, this assists to increase levels of transcription



Regulation

  • The repressor acts like an on-off switch

  • CAP can adjust the level of transcription (our cap) and increase the volume of transcription





How it fits together