Gene Regulation and Molecular Control in Eukaryotic and Prokaryotic Genomes

Gene Regulation

Timing/coordination of specific events necessary for normal development of organisms.

Homeotic (HOX) genes

Involved in developmental patterns and sequences.

Apoptosis

Programmed cell death that plays a role in development/differentiation.

Micro RNAs

Regulate genes and play a role in development and control of cellular functions.

Genetic mutations

Can result in abnormal development.

Environmental factors

Can influence gene expression, e.g., temperature and water availability determine seed germination.

Prokaryotic Genome

Use substances/synthesize macromolecules just fast enough to meet needs.

Operon

Related genes grouped together with one promoter for coordinated control of genes required for metabolism.

Operators

Regions of DNA that control RNA access to the promoter.

Repressor

Regulatory protein that binds to the operator and turns genes off.

Repressible Operons

Genes usually turned on; can be turned off by activating repressor.

Inducible Operons

Genes usually turned off; can be turned on by deactivating repressor.

Tryptophan

Corepressor that activates repressor when present.

Allolactose

Inducer that inactivates repressor for the lac operon.

Eukaryotic Genome Regulation

Genes are not grouped into operons.

Chromosome Structure

DNA packing and chemical modification involving histones.

Histones

Wrap DNA into beadlike bundles called nucleosomes.

DNA Methylation

Adding (-CH3) to cytosine blocks transcription.

Transcriptional Control

Involves the promoter region and binding of RNA polymerase/transcription factors.

TATA Box

Helps position RNA Polymerase at the promoter.

Enhancer Sequences

Upstream regions that speed up transcription by binding proteins.

Post-Transcriptional Control

Includes RNA processing, intron/exon editing, and nuclear transport.

Post-Translational Control

Involves RNA interference (RNAi), cleavage, and chemical modification.

Ubiquitin

Protein tag that identifies proteins for degradation.