Theme 2B Flashcards
What does an organisms phenotype depend on?
Cell number, type, and function
What is regenerative medicine
Growing the desire tissue type by turning on and off the corresponding genes through molecular techniques
What is a promoter
The DNA sequence on a gene that specifies where transcription begins on the chromosome
Promoter is recognized by RNA polymerase and transcription factors to start transcription
Where is the promoter located on the DNA strands?
On the five prime end of the start point of the coding strand
What is the transcriptional unit?
The part of the DNA that is coded (transcribed) into RNA
What does RNA polymerase do
Synthesizes RNA transcript in 5-3 direction
Read DNA template in 3 to 5
Doesn’t need primer to initiate rna synthesis (unlike dna pol)
Why don’t we need helicase in RNA transcription process?
Because RNA pol can unwind and rewind DNA strands on its own
What are the three types of RNA polymerase
RNA POL 1: rRNA, ribosomal rna
RNA POL 11: mRNA, only makes coding rna
RNA POL 111: tRNA
What is step one of transcription
Transcriptional initiation
How is transcriptional initiation mediated
The interaction of DNA-binding proteins to regulatory sequences of the gene (this determine whether gene is highly expressed or not)
Describe the first type of transcriptional initiation process
Initial General transcription factor bind to a TATA box in the promoter that is on DNA strand and recruit /call over RNA polymerase ll and other transcription factors
Has a low basal level of transcription (only one or two mRNA per hour)
Describe second type of transcriptional initiation process
Transcriptional, activator proteins, bind to regions far from the promoter that are enhancer regions. This causes DNA looping, which brings the enhancer and promoter closer together, resulting in high levels of transcription 
What is step two of the transcriptional process?
Transcriptional elongation
What happens in transcriptional elongation?
RNA POL ll moves along template DNA strand in 3 to 5 direction
RNA pol ll unwinds DNA at the front, and reanneals DNA at the back in the transcription bubble
The growing RNA transcript is separated from the template strand, and the two strands of DNA are reannealed into double stranded
What is step three of the transcription process?
Transcriptional termination
How does transcriptional termination start?
The sequence in the five prime end of the DNA template causes RNA POL to stop transcribing into RNA
What happens in RHO independent termination, what organisms does it occur in
Occurs in prokaryotes
Inverted coding repeats in dna are coding into rna causing the rna to pair with itself. This forms the GC hairpin and transcription stops. Rna strand separates from the template dna strand because of the hair pin
What happens in rho dependent termination, in what organisms does it occurs
In prokaryotes
The terminators sequence in mRNA is recognized by rho helicase. The rho helicase binds to the sequence and unwinds the RNA from the template dna and rna polymerase. This causes separation of rna from dna
What is cleavage and polyadenylation specific factor
What organisms does it occur in
Eukaryotes
The polyA sequence in mRNA signals the CPSF to cleave the finished mRNA transcript. This separates is from the rna polymerase
What is post transcriptional regulation of gene expression
The processing of rna molecule for stability and proper translation
What regions of mRNA is not translated
The ends (5 and 3 untranslated regions)
What do 5’ and 3’ UTR’s do.
Regulate mRNA stability and translational efficiency
If mRNA stable, it stays a long time, if unstable it degrades
What do 5 prime UTRS have and what do they do in translation
They have a ribosome binding site or a shine dalgarno sequence and kozack box sequences that help translational initiation (starting translation)
What is the open reading frame?
The part of the mRNA that is translated and includes the start and stop codons at the ends
