Exam 2 Flashcards
What is the order of the transcription steps?
- RNA polymerase II binds to the promotor
- DNA helix is unwound and RNA is synthesized
- Transcription is stopped by a hairpin loop
What two roles are played by the RNA polymerarse II during transcription?
- Binds to protein
2. unwinds the DNA helix and synthesizes RNA
The formation of what ends transcription?
Hair pin loop
List the three steps involved in processing RNA.
1) Add 5 prime Guansine triphosphate cap
2) Add a 3 prime Poly A tail
3) Splice out introns and rebond exons
What is the function of the spliceosome?
Removes introns
What is the order of the schematic nucleotides?
GU, A, AG
What is alternative splicing?
Allows the intron to become an exon
What is the difference between exons and introns?
Both are Transcribed
Exons are translated
Introns are never translated
What happens in the Aminoacyl site in translation?
Link an amino acid on a tRNA to a codon
What are the functions of the three types of RNA required for translation to take place?
mRNA- codes for protein
tRNA-serves as a link between AA and codon
Ribosomal-Peptide bond between amino acid
What is the start codon?
AUG
What are the Stop Codons?
UAG, UGA, UAA
Transcription factors bind two DNA sequence and one protein to increase expression of a gene. What are the DNA sequences and proteins?
Enhancer, Promotor and Polymerase II
The enhancer may be located tens of thousands of nucleotides away from the promotor. How does the transcription factor bind to the enhancer and promotor simultaneously to increase gene expression.
The DNA is flexible and can loop back to the enhancer
List the order of microRNA processing in the correct order.
1) Immature microRNA is transcribed from DNA
2) Drosha removes the hair pin loop
3) Dicer removes the loop in the hair pin loop
4) RISC removes the miRNA-star
What role does Drosha play in processing?
Cuts off the hairpin loop from the sequence
What role does Dicer play in microRNA processing?
Binds and degrades the hair pin loop
What role does the RNA-induced silencing complex play in microRNA processing?
Removes the miRNA
Compare and contrast repressor proteins and transcription factors in regulating gene expression
Both change gene expression
Repressors down regulate-sits on the promotor and blocks transcription, only binds to promotor
Transcription factors- up regulate-bind to enhancer and promotor
How does microRNA decrease gene expression when the microRNA is:
1) Completely complementary to mRNA
2) Partially complementary
1) RISC cleaves the mRNA
2) RISC can’t cleave but can sit on the sequence and prevents ribosome from translating
Define epigenetic.
Affects the expression of a gene but doesn’t change the actual genetic sequence.