Transcription Definition The use of DNA (cDNA--Complementary DNA) to produce a complementary strand of RNA (cRNA) During transcription, only ONE strand of DNA is used Remember, RNA is single stranded Students are to review RNA from Packet # 17 DNA is said to be transcribed into RNA RNA is called the transcript In the example provided in class, the RNA transcribed will be Messenger RNA (mRNA)

mRNA mRNA Messenger RNA An RNA molecule transcribed from the DNA of a gene Once mRNA is complete, proteins are translated from mRNA by the help of RIBOSOMES

Strands of Transcription Template Strand In transcription, known as the Complementary Strand (cDNA) A molecular “mold” that shapes the structure or sequence of another molecule Controls the nucleotide sequence of RNA during transcription Alignment guide “GUIDE”

Strands of Transcription Complementary Strand (cDNA) DNA transcribed from a specific RNA strand Complementary Strand (cRNA) RNA transcribed from a specific DNA single-stranded template

Genes The Review Where are genes located? On the chromosome What is the name of the location on the chromosome where genes are located? The Locus What are genes composed of? DNA

Regions of the Gene I Regulatory Region The Coding Region Receives signals from other genes or cellular environment This is where RNA Polymerase, the only enzyme used during transcription, binds on the DNA strand The Regulatory Region Has a region known as the Promoter Region The TATA Box is found in the Promoter Region The Coding Region Area where RNA nucleotides are joined together to make an RNA strand.

Transcription Step by Step Location Nucleus RNA Polymerase binds at the promoter region (sequence) and unzips the DNA strand RNA Polymerase works downstream adding RNA nucleotides to the 3’ end of the newly formed RNA strand New RNA strand grows in the 5’ to 3’ direction While transcribing, the RNA polymerase reaches nucleotide #20-40 5’ Cap is made Guanine is modified RNA Polymerase hits the “Terminator” sequence that signals the end of transcription Newly made RNA is released The New RNA strand is called pre-mRNA Why? Because the pre-mRNA needs to be “groomed” for the moment of Translation

Sections of pre-mRNA Contains introns and exons. Introns Exons The “Junk in the Trunk” Regions of the RNA strand that must be removed, via splicing, and will not be used during Translation Exons Regions of RNA that WILL be used and translated into amino acids during TRANSLATION

Splicing Eukaryotic Cells Removal of introns Location Nucleus of the Cell Enzyme used is Spliceosome Removes the introns via “cut & paste” After splicing, the pre-mRNA will be officially known as mRNA mRNA leaves the nucleus, through the nuclear pores, and enters the cytoplasm