How Genes Direct The Producton Of Proteins (Exam III) Flashcards
Cells achieve their specialized function based upon the expression of _______ and any subsequent ____ of the resulting proteins
Specific genes
Post-translational modifications
What is degraded more quickly DNA or RNA, and why
RNA
Because it undergoes nucleophilic attack of the ribose moiety
What degrade RNA very quickly
Ribonuclease
In both prokaryotes and eukaryotes you can have adjacent genes that get transcribed
In opposed directions
A segment of DNA that is transcribed into RNA and its associated transcriptional control regions
Gene
Transcriptional control regions of genes and RNA
Promotor regions
The type of RNA that is translated into proteins
Messenger RNA (mRNA)
The type of RNA that are important in transfer of amino acids to the growing peptide chain
Transfer RNA (tRNA)
Most abundant form of RNA
Ribsosomal RNA (rRNA)
Form of RNA that encodes ribosomal proteins
Ribosomal RNA (rRNA)
What form of RNA that blocks translation on specific mRNAs and thereby regulate gene expression
MicroRNA (miRNA)
What form of RNA turns off gene expression by directing the selective degradation of mRNAs
Small interfering RNAs (siRNAs)
What is the form of RNA that process and chemically modify rRNAs
Small nucleolar RNA (snoRNAs)
What form of RNA modify snoRNAs and snRNAs
Small cajal RNAs (scaRNA)
Involved in telomere synthesis, X-chromosome inactivation and protein transport into the ER
Other non coding RNAs
Make up abut 80% of all RNAs in the cell
Ribosomal RNAs (rRNA)
Abundance of tRNA in the cell
15%
Abundance of mRNA in the cell
3-5%
All RNAs have to be transcribed from a
Gene in the genome
In eukaryotic organisms most protein coding genes are transcribed by
RNA polymerase II
When you see RNA polymerase II think:
Protein coding
Transcription always starts at a ______ point in the DNA and requires unwinding of the DNA to creat the proper single-stranded template
Specific
Gene expression is regulated by numerous transcription factors that interaction with _____ in DNA and/or proteins bound to these regions
Promoter elements
The presence/absence of specific factors is an obligatory first step in the initiation of ______ bindign and subsequent RNA polymerase binding
TBP/TFIID
A very important sequence of the 5’ side (start site) of transcription
TATA box
Transcription starts at (what base)
Base 1
TATA Box is rich in
Thymine and and adenine (maybe thymadine)
The TAT box will bind a very important transcription factor called:
TBP and TFIID (transcription factor IID)
The dimer that TATA box binds to is composed of
TBP and TFIID
The TATA box localized the dimer protein (TBP TFIID) to position itself relative to the start of transcription through
the binding of TBP to the TATA box
Following the TATA box binding TBP and positioning it, this allows _____ to bind and position itself
TFIID
After positioning the TBP and TFIID factor properly:
TFIIB comes in and postitions itself
The binding and positioning of TFIIB leads to the recruitment of
A bunch of other factors
Once the TATA box has bound TBP and TBP allows for the correcting positioning of TFIID and TFIID allows for the correct positioning of TFIIB and TFIIB recruits all the other important factors/molecules, this will allows for the correct positioning of
RNA Polymerase II
It is important that RNA polymerase II positions itself
Around the DNA molecule in the proper place
The RNA polymerase should be bound on the DNA so that the start site of transcription will occur at:
Nucleotide 1
The TATA box is located:
Left to the start site of transcription (-15 to -25 to the start site)
Once the RNA Polymerase II has bound there is a _____ that wraps around the DNA
CTD (cytoplasmic tail domain)
A couple of ______ reactions occur on the cytoplasmic tail domain of the RNA polymerase II
Phosphorylation
The phosphorylation reactions on the CTD of the RNA polymerase II leads to the
Disassembly of a lot of these general transcription factors
When we have the disassembly of most of the general transcription factors caused by phosphorylation reactions on CTD this allows for _____ activity and a _____ that is ready to go
Helicase
RNA polymerase
Inside the binding pocket of the RNA polymerase, what is functioning
Helicase
The RNA polymerase is adding ________ to the growing transcript through the uptake channel
Ribonucleoside triphosphates
On the growing mRNA transcript, the 5’ ______ is connecting to the 3’ ______
5’ Phosphate
3’ hydroxyl
RNA is NOT just a _____ because it can fold back on itself and basepair
Linear molecule
Key transcription factor TFIID is made of
TBP subunit + TAF subunit
The TBP subunit of TFIID recognizes
TATA box
The TAF subunit of TFIID recognizes other ____ sequences near the transcription start points and regulates DNA-binding by _____
DNA sequence
TBP
The TFIIB recognizes the ____ element in promotors
BRE
The TFIIB accurately positions _________ at the start site of transcription
RNA polymerase II
What element is important for accurately positioning the RNA polymers at the transcriptional start site
BRE
All of the RNA Polymerases have a preference for the types of genes that they bind
RNA polymerase I:
RNA polymerase II:
RNA polymerase III:
RNA polymerase I: rRNA genes
RNA polymerase II: Protein-coding genes, snoRNA genes, miRNA genes, siRNA genes and most snRNA genes
RNA polymerase III: tRNA genes
Capping, splicing, editing, polyadenylation and transport are all
mRNA processing events
The guanisine cap is added to the
5’ end of the mRNA
In protein coding gene, there is an addition of a poly-A tail added to the 3’ end of the mRNA - this is called
Polyadenylation
Transport of mRNA involves the movement out of the _____ and into the ____
Nucleus
Cytoplasm
Linear coding sequence is made up of all of the _____ that have been added together
Exons
In mRNA processing, the 5’ and 3’ untranslated regions get:
Kept in the linear sequence
Splicing occurs by a complex of RNA and protein molecules collectively known as the
Splicesome
The splicesome is largely made up of _______ in a complex with _____ protein subunits to form an SNP
SnRNAs
7
The snRNAs provide proper base pairing with the mRNA so that the protein complex within them is:
Positioned correctly
If the mRNA is not spliced correctly, the their may be the presence of either (2)
Extra nucleotides that will get translated
Missing exons
Splicing will take the ____ end of exon 1 and attach it to the ____ end of exon 2
3’
5’
The splicing process initially involves the formation of a:
Lariat
The formation of a lariat involves a particular _____ residue in the intron sequence that undergoes a ____ attack at the junction between an intron and exon to create a loop structure
Adenosine
Nucleophilic
The loop structure created in the initial steps of the splicing mechanism ultimately is the portion that:
Gets spliced out
Splicing requires very specific sequences that are at:
The junction of the intron and exon
Initiates the formation of a lariat structure
Adenosine residue
The sequences important for where splicing will occur are located in the
Introns
An example of a highly spliced gene
Alpha-tropomysoin gene
The tropomysoin gene has dozens of different splice variants that all give rise to a different tropomyosin protein that is a ______ from one form to the next, therfore it will behave slightly different
Isoform
Both the 5’ cap and splicing of the primary mRNA transcript occur as:
The transcript starts to emerge from the RNA polymerase
Following the addition of the 5’ cap and the splicing of the primary mRNA transcript, a _______ is added to the 3’ end of the mRNA
Poly-A tail
The poly-A tail is not added until the mRNA transcript:
Completely emerges from the RNA polymerase
Once the mRNA is mature, it is then exported from the nucleus through a specific export-mediated process to the _______ and then into the _______ where protein synthesis will occur
Cytoplasm
Rough endoplasmic reticulum
A very important regulator of mRNA
MicroRNA (miRNA)
Changes in miRNA behavior have been linked to:
Disease in human
Small non-coding RNAs about 21-25 nucleotides long
MicroRNAs (miRNAs)
MicroRNAs principally bind the the _____ of the target mRNA
3’ UTR (Untranslated region)
When a microRNA (miRNA) binds to the 3’ UTR of the target mRNA it forms an:
RNA-inducing silencing complex (RISC)
Suppress protein synthesis and/or reduce mRNA degradation
(Ultimately regulation of mRNA by miRNA)
RNA-inducing silencing complex (RISC)
The enzyme that functions to clip the bulge in pre-miRNA in order to create mature miRNA
Dicer
Regulation of miRNA biogenesis is an important target being looked at in:
The control of many diseases
3 bases are required to code for:
A single amino acid
The 3 base sequence that codes an amino acid
Codon
The genetic code is ______ for all organisms (essentially the same)
Universal
Important features of the genetic code (4)
1- “commaless”
2- degenerate
3- third base in codon is less specific than first two
4- 3 out of the 64 possible codons do not signal for amino acids but instead for termination
How many possible codons signal the 20 amino acids
64
How many codons signal for termination
3
Prenatal growth retardation (mild to severe), craniofacial abnormalities such as microcephalic and cleft lip/palate and limb malformations are all potential effects of
Roberts syndrome
Homozygous mutation of ESCO2 causes what disease
Roberts disease
The homozygous mutation in ESCO2 encodes a ______ important for the formation of the cohesion complex that binds to chromosomes and creates cohesion between sister chromatids
Acetyltransferase
If you dont make enough/transcribe enough ribosomal genes that can lead to defects in
Protein synthesis
Ribosomal biogenesis is extremely important and if not properly regulated can lead to
Numerous problems and defects
