Transcription

Transcription

is the process of copying a gene’s DNA sequence into RNA

Transcription

It’s the first step of gene expression, turning genetic information into a message that can eventually be used to make proteins.

Transcription

• In eukaryotes, it happens in the nucleus, while translation occurs in the cytoplasm.

Transcription

is the bridge between DNA (information storage) and translation (functional proteins).

Transcription

• When: Throughout interphase, whenever a gene is expressed.

• Where: Nucleus.

Initiation

• RNA polymerase binds to the promoter region with help from transcription factors.

• DNA strands separate.

Elongation

RNA polymerase builds a single-stranded RNA transcript complementary to the DNA template strand (U pairs with A).

Termination

RNA polymerase reaches a terminator sequence and detaches.

RNA Processing

• 5′ cap added (protection + ribosome attachment).

• Poly-A tail added (stability).

• Introns (noncoding) removed; exons (coding) spliced together.

Transcription

Outcome: A mature mRNA that carries the genetic code from DNA to the cytoplasm.

Transcription

From DNA to RNA

RNA polymerase

synthesizes RNA, pries DNA apart, joins nucleotides.

Promoter

DNA sequence where RNA polymerase binds.

Terminator

DNA sequence that signals transcription stop.

Transcription unit

region of DNA transcribed into RNA.