Transcription and RNA

Flashcards of key vocabulary terms regarding transcription and RNA.

DNA

The blueprint that is transcribed into mRNA.

mRNA

Is then translated into proteins.

Gene Expression

Before genes can be used to produce proteins, DNA must be converted into RNA; the two steps in gene expression are transcription and translation.

Transcription

A DNA sequence serves as a template for the synthesis of RNA.

Translation

An mRNA sequence serves as a template for the synthesis of a protein.

RNA

A messenger to transfer the genetic code to the ribosomes because DNA cannot leave the nucleus, but proteins are built by the ribosomes in the cytosol in eukaryotes.

Initiation Phase

The first phase of transcription; the correct transcription start site is selected and the transcription machinery, composed of a large protein-DNA complex, is assembled.

Template strand (antisense strand)

For each gene, only one strand of DNA is transcribed; this strand.

Coding strand (sense strand)

The strand that is not transcribed in transcription; this strand has the same sequence as the mRNA that is produced, with thymine instead of uracil.

Promoter

A region of 100-1000+ base pairs AHEAD (UP stream) of a gene; determines where RNA polymerase binds to on DNA and where transcription begins; usually rich in Thymine and Adenine

RNA Polymerases

Catalyzes transcription; transcription factors are other proteins and molecules that bind to DNA and recruit RNA polymerase to begin transcribing that gene

Elongation

The bound RNA polymerase “unzips” the two strands of DNA forming an “Open complex;” nucleotides are added in a 5’ to 3’ direction; the new RNA molecule is complimentary to the template strand—corresponds to coding strand but with U’s instead of T’s.

Termination

Specific nucleotide sequences in the DNA template serve as a signal to stop transcription; when the RNA polymerase complex reaches this signal, a hair pin loop is created in the mRNA and it released

Exons

Genes contain both coding regions.

Introns

Genes contain both non-coding regions.

Removal of Introns

Are removed and exons are joined together by small nuclear RNA (snRNA) and small nuclear ribonucleic particles (snRNP) proteins, which form a large spliceosome complex.