Types of RNA and RNA polymerase

mRNAs

messenger RNAs, code for proteins

rRNA

Forms basic structure of ribosome and catalyzes protein synthesis

tRNAs

Used in translation as adaptor between mRNA and AAs

snRNAs (small nuclear RNA)

Involved in various nuclear processes including splicing of pre-mRNA

miRNA (microRNA)

Regulates gene expression by blocking translation of specific mRNAs and cause their degradation

siRNA

Turn off gene expression by binding to target mRNA

SnoRNA (small nucleolar)

Help process & chemically modify rRNAs

piRNA (piwi-interacting)

Binds to piwi protein & protect the germ line from transposable elements

lncRNA (long non-coding RNA)

Regulates diverse cell processes including X-chromosome inactivation by binding a specific gene sequence to recruit proteins that modify chromatin of a gene, resulting in transcriptional repression or activation.

RNA polymerase I

Transcribes 5.8s 18s and 28s rRNA genes

RNA polymerase II

Transcribes all protein-coding genes, miRNA genes, snRNA, plus genes for other noncoding RNAs like lncRNA snoRNA and

RNA polymerase III

transcribes tRNA genes, 5s rRNA genes, some snRNA genes & genes for other small RNAs