Transcription Notes

DNA TRANSCRIPTION

OVERVIEW
Changes DNA to mRNA
Happens in nucleus mRNA is an RNA copy of the DNA for the protein
The mRNA will carry the message to the ribosomes to be translated into a protein

STEPS OF TRANSCRIPTION IN PROKARYOTES
In order for transcription to take place the strand must be unzipped but only the area where the gene is on the chromosome
RNA polymerase is the enzyme responsible for reading and unzipping the strand
Two strands on DNA- one is read and one is not
Sense strand- the strand that is not read
Anti-sense strand/template- strand used to make RNA
RNA polymerase binds to the anti sense strand at a place called the promoter
Promoters usually have bases that go TATA
TATA box
Begins to read strand in 3’ to 5’ direction; builds mRNA in a 5’ to a 3’ direction
RNA polymerase add bases as it goes takes ribonucleside triphosphates, clips off two phostphates, creates ribonucleotides
Clipping of phosphates creates energy needed to form bonds with ribonucleotides
Continues until it reaches an area called the terminator
Terminator causes mRNA and polymerase to release
Product: mRNA transcript
Transcript then goes to the ribosome to be translated

DIFFERENCES IN EUKARYOTES
1. Transcription continues past termination sequence for a significant number of nucleotides
2. Eukaryotic has long stretches of non-coding regions
a. Non-coding regions (introns) removed from mRNA
b. Leftover area (exon) forms all mRNA
c. Prokaryotes don’t have to clip out introns (don’t have them)

VERVIEW
Changes DNA to mRNA
Happens in nucleus mRNA is an RNA copy of the DNA for the protein
The mRNA will carry the message to the ribosomes to be translated into a protein

STEPS OF TRANSCRIPTION IN PROKARYOTES
In order for transcription to take place the strand must be unzipped but only the area where the gene is on the chromosome
RNA polymerase is the enzyme responsible for reading and unzipping the strand
Two strands on DNA- one is read and one is not
Sense strand- the strand that is not read
Anti-sense strand/template- strand used to make RNA
RNA polymerase binds to the anti sense strand at a place called the promoter
Promoters usually have bases that go TATA
TATA box
Begins to read strand in 3’ to 5’ direction; builds mRNA in a 5’ to a 3’ direction
RNA polymerase add bases as it goes takes ribonucleside triphosphates, clips off two phostphates, creates ribonucleotides
Clipping of phosphates creates energy needed to form bonds with ribonucleotides
Continues until it reaches an area called the terminator
Terminator causes mRNA and polymerase to release
Product: mRNA transcript
Transcript then goes to the ribosome to be translated

DIFFERENCES IN EUKARYOTES
1. Transcription continues past termination sequence for a significant number of nucleotides
2. Eukaryotic has long stretches of non-coding regions
a. Non-coding regions (introns) removed from mRNA
b. Leftover area (exon) forms all mRNA
c. Prokaryotes don’t have to clip out introns (don’t have them)

VERVIEW
Changes DNA to mRNA
Happens in nucleus mRNA is an RNA copy of the DNA for the protein
The mRNA will carry the message to the ribosomes to be translated into a protein

STEPS OF TRANSCRIPTION IN PROKARYOTES
In order for transcription to take place the strand must be unzipped but only the area where the gene is on the chromosome
RNA polymerase is the enzyme responsible for reading and unzipping the strand
Two strands on DNA- one is read and one is not
Sense strand- the strand that is not read
Anti-sense strand/template- strand used to make RNA
RNA polymerase binds to the anti sense strand at a place called the promoter
Promoters usually have bases that go TATA
TATA box
Begins to read strand in 3’ to 5’ direction; builds mRNA in a 5’ to a 3’ direction
RNA polymerase add bases as it goes takes ribonucleside triphosphates, clips off two phostphates, creates ribonucleotides
Clipping of phosphates creates energy needed to form bonds with ribonucleotides
Continues until it reaches an area called the terminator
Terminator causes mRNA and polymerase to release
Product: mRNA transcript
Transcript then goes to the ribosome to be translated

DIFFERENCES IN EUKARYOTES
1. Transcription continues past termination sequence for a significant number of nucleotides
2. Eukaryotic has long stretches of non-coding regions
a. Non-coding regions (introns) removed from mRNA
b. Leftover area (exon) forms all mRNA
c. Prokaryotes don’t have to clip out introns (don’t have them)