Chapter 12 Gene Transcription and RNA Modification Flashcards
What is transcription?
making a copy. Synthesizing RNA from a DNA sequence
What are structural Genes?
Genes that encode amino acids of polypeptides.
What is a promoter?
provides site for start of transcription. Short sequence of DNA that is necessary to initiate transcription.
What is a terminator?
provides site for stop of transcription
what are coding strands?
non-template strands
What are transcription factors?
factors that recognize base sequences and control transcription
Regulatory sequences?
Regulators of transcription. Increase or decrease rate of transcription
What is ribosome binding site?
short sequence on mRNA that binds and begins translation
Codon
located in mRNA read in groups of three nucleotides
What are the three stages of transcription?
Initiation, Elongation, Termination
How are promoters numbered
in relation to transcriptional start site. (first base used as template for RNA). Numbered in negative direction with no zero
What are subunits of core enzymes?
5 subunits (sixth is sigma)
What do alpha subunits do?
there are two and they help properly assemble haloenzymes in process of binding DNA
What do Beta and Beta’ do?
needed for binding DNA and carrying out synthesis
What does omega do?
Reconginzes promoter
what do haloenzymes do?
inititatie transcription
Initiation in detail:
Loosley bound haloenzymes slide down DNA strand. recogniezes the promoter and -35 and -10 region. Omega has helix turn helix motif structure that binds tightly to promoter. Alpha helixace fit into grooves and form hydrogen bonds. Forming a closed complex. Double stranded DNA unwound and -10 region.
what is p dependent termination?
termination requiring protein p(rho)
What does p(rho) create?
Stem loops which stop transcription
What does RNA poly 1 do in eukaryotic transcription?
Trancribes all genes that encode ribosomal RNA (rRNA)
What does RNA poly 2 do in eukaryotic transcription?
cellular transcription because it transcribes all structural genes (sRNA)
What does RNA Polly 3 do in eukaryotic transcritption
Transcribes tRNA
What is core promter composed of?
Promter, tata box, trascriptional start site
Cis Elements
Exert effect over super close genes
Trans
Can be far from gene they control
When is the transcription of Eukaryotic Structural genes inititated?
When RNA Poly II and general transcription factors bind to promoter
What is allosteric model
After transcription poly II is destabalized due to release of elongation factors
Torpedo Model
Endonucleus binds to 5 end and starts degrading 5 to 3
What is colinearity?
one to one ration btw sequences of codons
Exons
Regions within mRNA
Introns
found btw exxons
RNA splicing
introns removed exons connected
Self Splicing
occurs btw groups 1 and 2
Pre-mRNA
located in nucleus altered by splicing but needs splicosomes to occur
Spliceosomes
composed of snurps which are made of RNA and protein
What is the function of spliceosomes?
Find to introns
hold pre-mRNA in correct config
cataylze reacction that removes intron
What is alternative splicing and is it advantageous?
variation in splicing do to multiple introns. And YES
what is 5’ cap and what is its function?
1) recognizes binding proteins required for proper exit of mRNA from nucleus
2) Cap binding recognized by initiation factors needed for first step of translatoin
3) efficient splicing of introns
Poly A Tail
Important in eukaryotes string of adenine nuclteotides important for mRNA stability and synthesis of polypeptides
