transcription Flashcards
Why do we need mRNA between
DNA and Protein?
Because one mRNA molecule can make many
proteins therefore amplifying the process
Few mRNAs can translate may different proteins
Gene expression
the process by which DNA
directs the synthesis of polypeptides through mRNA
when does gene expression occur
Gene expression occurs through transcription of the
DNA into mRNA which then serves as the template
for protein synthesis
what is Beadle and Tatum gene theory
scientists working with the mold Neurospora
crassa, hypothesized that a gene would encode for
an enzyme
- Today it is one gene one polypeptide because
some proteins are composed of more than one
polypeptide in order to be functional
does the rna poly 2 need help to find the region of DNA to be transcribed
no
the roles of transcription and translation in the flow of
genetic information in Eukaryotes
pre-mrna—> processed to mrna —> transported to cytosol—->translated into proteins
The transcription unit in eukaryotes
one transcription unit = one gene
the transcription unit of prokaryotes
one transcription unit = many genes
what is transcription
the synthesis of
RNA under the direction of DNA
what are the steps in transcription
Binding of RNA Polymerase II • Unwinding of the DNA • Initiation • Elongation • Termination
what happens during DNA replication
both strands must be copied at the same
time
when dna transcribed into rna how many can be copied at a time
only one strand is copied at a time, although both strands can be copied
what does • RNA polymerase II do
elongates the RNA much like DNA polymerase III does for DNA but uses ribonucleotides instead of deoxiribonucleotides
The stages of transcription components
Only one strand is transcribed at a time • The RNA polymerase II untwists one turn of the DNA helix at a time • The terminator sequence in prokaryotes signal the end of transcription a promoter, the structural gene, and a terminator
what is transcription direction
both strands of dna can be read
- but only one at a time
- reading can only be done in 3’ to 5’ direction
how is rna synthesized (what direction)
in 5’ to 3’ direction much like DNA
reading of coding strand, template, and rna
coding strand-5’ to 3’
template- 3’ to 5’
rna- 5’ to 3’
does the eukaryote cells poly 2 needs help to find promoter region
yes!
what are transcription factors
proteins involved in the process of converting, or transcribing, DNA into RNA
how does RNA poly 2 start transcription
finds transcription proteins and binds to promoter region
what are introns and exons
Introns are removed by RNA splicing as RNA matures, meaning that they are not expressed in the final mRNA product, while exons go on to be covalently bonded to one another in order to create mature mRNA
are introns translated
no. they are spliced out by small snRNPs
where do The 5 cap and the poly A tail get added and RNA splicing occur
nucleus
what is Poli a tail
short sequence containing nucleotides made of adenine that protects the mRNA from degradations and guides it through the nucleopores to the cytosol
