Transcription
The process of Transcription
DNA transcription is a process that involves transcribing genetic information
from DNA to RNA. The transcribed DNA message, or RNA
transcript, is used to produce proteins. DNA is housed within the nucleus of our cells. It controls cellular activity by coding
for the production of proteins. The information in DNA is not directly converted
into proteins, but must first be copied into RNA. This ensures that the
information contained within the DNA does not become tainted.
DNA TranscriptionDNA consists of four nucleotide bases [adenine (A), guanine
(G), cytosine (C), and thymine (T)] that are paired together (A-T and
C-G) to give DNA its double helical shape. Nucleotide base sequences
are the genetic code or instructions for protein synthesis.
There are three main steps to the process of DNA transcription.
Since proteins are constructed in the cytoplasm of the cell, mRNA must cross the
nuclear membrane to reach the cytoplasm. Once in the cytoplasm, ribosomes and another RNA molecule called transfer
RNA work together to translate mRNA into a protein. This process
is called translation. Proteins can be manufactured in
large quantities because a single DNA sequence can be transcribed by many RNA
polymerase molecules at once.
(http://biology.about.com/od/cellularprocesses/ss/Dna-Transcription.htm)
from DNA to RNA. The transcribed DNA message, or RNA
transcript, is used to produce proteins. DNA is housed within the nucleus of our cells. It controls cellular activity by coding
for the production of proteins. The information in DNA is not directly converted
into proteins, but must first be copied into RNA. This ensures that the
information contained within the DNA does not become tainted.
DNA TranscriptionDNA consists of four nucleotide bases [adenine (A), guanine
(G), cytosine (C), and thymine (T)] that are paired together (A-T and
C-G) to give DNA its double helical shape. Nucleotide base sequences
are the genetic code or instructions for protein synthesis.
- RNA Polymerase Binds to DNA
DNA is transcribed by an enzyme called
RNA polymerase. Specific nucleotide sequences tell RNA polymerase where to begin
and where to end. RNA polymerase attaches to the DNA at a specific area called
the promoter region.
- Elongation
Certain proteins called transcription factors unwind the
DNA strand and allow RNA polymerase to transcribe only a single strand of DNA
into a single stranded RNA polymer called messenger RNA (mRNA). The strand that
serves as the template is called the antisense strand. The strand that is not
transcribed is called the sense strand.
Like DNA, RNA is composed of
nucleotide bases. RNA however, contains the nucleotides adenine, guanine,
cytosine, and uracil (U). When RNA polymerase transcribes the DNA, guanine pairs
with cytosine and adenine pairs with uracil.
- Termination
RNA polymerase moves along the DNA until it reaches a
terminator sequence. At that point, RNA polymerase releases the mRNA polymer and
detaches from the DNA.
There are three main steps to the process of DNA transcription.
Since proteins are constructed in the cytoplasm of the cell, mRNA must cross the
nuclear membrane to reach the cytoplasm. Once in the cytoplasm, ribosomes and another RNA molecule called transfer
RNA work together to translate mRNA into a protein. This process
is called translation. Proteins can be manufactured in
large quantities because a single DNA sequence can be transcribed by many RNA
polymerase molecules at once.
(http://biology.about.com/od/cellularprocesses/ss/Dna-Transcription.htm)