SEMINAR ON GENE REGULATION

Submitted bySaarika P KRoll NO: 15

Reg No: 11-00053-2012

ContentsGene regulation

Importance or significance of gene regulation

Differences between prokaryotic and eukaryotic gene regulation

This is the process of turning genes on or off.

This regulation is driven by protein regulators-Activators and Repressors, and the proteins theyrecruit to genes .

Importance of gene regulation To control the amount of gene product present in the

cell.

To allow cells to adjust with changing conditions.

Specialization and division of labor among cells.

Expression of appropriate genes at proper time.

Synchronized regulation of multiple genes encodingproducts with interdependent activities.

Prevent the wastage of cellular energy.

Prokaryotic and eukaryotic gene regulation

In prokaryotic organisms gene regulation occurs insame cell but different time.

In eukaryotic organisms gene expression isregulated at same time but different cells.

Differences in gene regulationEukaryotes Prokaryotes

Eukaryotic organisms havemore complex regulatorypathways.

In eukaryotes short termcontrol and long term controlof gene expression is present.

Much longer set of regulatorysequence are presentindividually for each gene.

Simple regulatory pathwaysare followed.

Life span of prokaryotes arevery less . so long termcontrol of gene expression isabsent.

Single and short regulatorysequence is present all overthe DNA molecule.

Cont….

EukaryotesProkaryotes

The default setting in eukaryoticgene expression is normally offuntil it get activated.

Transcriptional ground state isrestrictive, so mostly positiveregulation of gene is present.

Activator binding site locationcan extend up to 50 kb from thepromoter. “Action at a distance”

The system in bacteria is allowfor the continuous expression ofgene. The system in bacteria isallow for the continuousexpression of gene.

Transcriptional ground state isnon restrictive, so positive andnegative regulation occur inalmost same frequency.

Activator binding site should belocated with in 3 kb from thepromoter. “action from adistance”

Cont…

Eukaryotes Prokaryotes

Eukaryotic genes also areregulated in units of protein-coding sequences andadjacent controlling sites, butoperons are not known tooccur.

Some hormonal regulation ofgene is occurring ( steroidhormones).

Novel repression mechanism, RNAi (interference) ie, genesilencing is present.

Prokaryote gene expressiontypically is regulated by anoperon, the collection ofcontrolling sites adjacent topolycistronic protein-codingsequences.

Hormonal regulation isabsent.

Gene silencing mechanism isabsent.

Cont…Eukaryotes Prokaryotes

The regulatory proteins actsas hetero dimers ,homeodimers, leucine zipper,zinc finger etc…

The regulatory proteins bindto DNA molecule ishomodimer.

Homodimer

DNA binding site and protein binding site are composed of same type of units

Heterodimer

DNA binding site and protein binding site are of different units

REFERENCESPrinciples of biochemistry,Molecular biology of the gene- WatsonIntroduction to Genetics- Terry Brown