DNA Chapter 7.4 Flashcards
Uses a DNA template to create RNA.
. Transcription produces an RNA copy of one gene
.the cells uses the information from RNA and not the DNA directly to make each protein.
Transcription vs DNA replication ( the 2 main differences
Complementary base pairings underlies transcription just as it does DNA replication. They resemble except for:
- The product of transcription is RNA , not DNA
- Transcription copies just one gene from DNA strand, rather than copying both strands of an entire chromosome.
In Transcriptiion, RNA nucleotides base binds with
exposed complementary bases on the template strand ( which is the strand in the DNA molecule that is actually copied to RNA
The strand in the Dna molecule that is actually copied to RNA
The 3 Steps of Transcription
- Enzymes unzip The DNA double helix, exposing the template strand.
- RNA POLYMERASE ( the enzyme that builds an Rna chain) binds to the PROMOTER (A DNA sequence that signals the gene’s start)
the enzyme that builds an Rna chain
A DNA sequence that signals the gene’s start
RNA polymerase moves along the DNA template strand in a 3’ to 5’ direction, adding nucleotides only to the 3’-end of the growing RNA molecule. ( the creating of the copy of the DNA template: the copy: mRNA )
- A TERMINATOR sequence signals the end of the gene.
- Upon reaching the terminator sequence, the RNA POLYMERASE enzyme separates from the DNA template and releases the newly synthesized RNA. ( mRNA)
- The DNA molecule resumes its usual double helix shape
What happens to the RNA molecule as it is synthesized
It curls into a 3 dimensional shape dictated by complementary base pairing within the molecule
What does the final shape of RNA determines
whether the RNA functions as mRNA, rRNA, OR tRNA.
. What happens during each stage of transcription
The steps of transcription are initiation, elongation of the RNA molecule, and termination. During initiation, enzymes unzip the DNA and RNA polymerase binds. During elongation, RNA polymerase “reads” the DNA strand and adds complementary nucleotides to the growing RNA strand. During termination, synthesis of the RNA molecule ends and the DNA molecule reforms.
Where in the cell does transcription occur
Transcription occurs in the nucleus.
What is the role of RNA polymerase in transcription?
RNA polymerase uses the DNA template to bind additional RNA bases into the growing chain of RNA being transcribed.