Histone Deacetylation = removal of acetyl groups

When lysines are acetylated, the histone tails do not bind to neighboring nucleosomes. When binding does not occur, chromatin has a looser structure. This gives transcription proteins easier access to genes in acetylated regions.

DNA methylation is essential in some organisms and cases for long-term inactivation of genes for cell differentiation in embryonic stage

Epigenetic inheritance = inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence (methylation is one such mechanism)

Control elements are extremely important for the precise regulation of gene expression seen in different cell types

General transcription factors = essential for all protein-coding genes - bind to TATA box to initiate transcription

Specific transcription factors = in eukaryotes - high levels of transcription of particular genes that is controlled depends on control elements with set of proteins (specific transcription factors)

Enhancers = distal control elements upstream or downstream of a gene or even within an intron that can, in eukaryotes, control the rate of transcription

Alternative RNA splicing = different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns

Allows the "repertoire" of eukaryotic genome to expand

mRNA degradation in prokaryotes = short life span quickly degraded by enzymes within few minutes of synthesis

mRNA degradation in eukaryotes = long life span - can survive for hours, days, or even weeks

Nucleotide sequences, often in the UTR, affect how long an mRNA remains intact

Regulatory proteins activated or inactivated by reversible addition of phosphate groups

To mark a specific protein for destruction - cell adds molecules of ubiquitin (small protein)

Proteasomes = giant protein complexes which then recognize the ubiquitin tagged proteins and degrade them