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78 Cards in this Set
- Front
- Back
1/5 of all disease alleles affect splicing?
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True
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1/5 of all disease alleles affect splicing?
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True
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Describe bact transcription translation?
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occurs simultaneously
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Describe bact transcription translation?
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occurs simultaneously
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Spinal Musclular Atrophy
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autosomal recessive disease; progressive degenerative; alpha motor neurons; incidince is 1/6000 live births
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Spinal Musclular Atrophy
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autosomal recessive disease; progressive degenerative; alpha motor neurons; incidince is 1/6000 live births
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Duchenne Muscular Dystrophy
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X linked recessive; 1/3000 per male births
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Duchenne Muscular Dystrophy
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X linked recessive; 1/3000 per male births
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Bacterial vs. Eukaryotic DNA
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-Bacteria are both poly and mono cystronic
-Euk mRNA is monocistronic -5' and 3' ends are unmodified in prok bacteria -in euk transcription/translation occur separately |
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Bacterial vs. Eukaryotic DNA
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-Bacteria are both poly and mono cystronic
-Euk mRNA is monocistronic -5' and 3' ends are unmodified in prok bacteria -in euk transcription/translation occur separately |
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Mono cystronic
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1 mRNA coding for 1 protien
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Mono cystronic
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1 mRNA coding for 1 protien
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Polycistronic
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1 mRNA coding for more than 1 protein
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Polycistronic
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1 mRNA coding for more than 1 protein
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Dumping bacteria in new environment what hapenes?
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It turns on different metabolic pathway; it puts new genes on a single operon; and it will automatically get the same amount of required proteins
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Dumping bacteria in new environment what hapenes?
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It turns on different metabolic pathway; it puts new genes on a single operon; and it will automatically get the same amount of required proteins
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Describe EUK transcription
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messages are transcribed as premRNAs by pol2; and processed by
1. attaching a cap to the 5' end of the mRNA 2. by adding a poly A tail to the 3'end of the mRNA 3. by excising the introns to join the exons in the coding region (occurs by a large RNA protein complex called the splicosome) |
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Describe EUK transcription
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messages are transcribed as premRNAs by pol2; and processed by
1. attaching a cap to the 5' end of the mRNA 2. by adding a poly A tail to the 3'end of the mRNA 3. by excising the introns to join the exons in the coding region (occurs by a large RNA protein complex called the splicosome) |
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Splicing occurs in both euk and pro?
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Yes; it is the norm in EUK; PRO have way less.
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Splicing occurs in both euk and pro?
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Yes; it is the norm in EUK; PRO have way less.
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Describe Pol 2 Structure
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5' cap = 7 methyl guanosine triphosphate cap (special enzymes place this cap on/ as well as bind and recognize it)
at the end we have a signal sequence and a poly A tail |
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Splicing joins excising introns
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Splicing varies in an enormous amount depending on nucleotide pairs. Sometimes the exons are incredibly small in size in comparison to the introns.
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Intronic gene
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vast majority of the DNA is used to code for introns (humans)
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what is typical of noncoding RNA
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most of them do not have any introns
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Name a few noncoding RNAs
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tRNA, miRNA, snRNA etc.
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Large variation in human genes
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average human gene is 2500 base pairs but considerable variation exists
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A typical gene contains how many introns and how many exons?
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8 and 9
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What is the gene with largest amount of exons
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Titin
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What are the 5 particles that carry out splicing?
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U1, U2, U4, U5, U6 (has to do with size)
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what about U3?
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not involved in splicing
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Describe Pol 2 Structure
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5' cap = 7 methyl guanosine triphosphate cap (special enzymes place this cap on/ as well as bind and recognize it)
at the end we have a signal sequence and a poly A tail |
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Splicing joins excising introns
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Splicing varies in an enormous amount depending on nucleotide pairs. Sometimes the exons are incredibly small in size in comparison to the introns.
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Intronic gene
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vast majority of the DNA is used to code for introns (humans)
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what is typical of noncoding RNA
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most of them do not have any introns
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Name a few noncoding RNAs
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tRNA, miRNA, snRNA etc.
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Large variation in human genes
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average human gene is 2500 base pairs but considerable variation exists
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A typical gene contains how many introns and how many exons?
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8 and 9
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What is the gene with largest amount of exons
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Titin
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What are the 5 particles that carry out splicing?
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U1, U2, U4, U5, U6 (has to do with size)
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what about U3?
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not involved in splicing
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The spliceosome is made of 5 small nuclear RNA proteins called?
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snRNPs
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Systemic lupus. what happens?
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Patients develop antibodies against their own proteins including snRPS
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What is the process in which introns are excised and exons are joined together?
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Splicing
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5' end of the intron has what universal sequence?
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GU
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at 3' end of the intron has?
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AG
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The A in the intron is a ?
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branch point
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Do you know where the 5' splice site is? and the 3' splice site?
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Yes; the 2' OH of the A branchpoint attacks the 5' splice site; and you get the free floating 5' exon, which is held by the splicosome;
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What happens after the 5' exon is held on?
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the 3' OH of the 5' exon attacks the 3' splice site to join the 5' and 3' exons
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Where does this attack and ligation occur?
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on the splicesome
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Describe how spliceosome RNPs direct splicing?
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1) U1 binds to 5' splice site; branch point binding protein (BBP) and U2 auxillary factor (U2AF)
2) U2 recruitment displaces BBP and U2AF; ATP is utilized 3)U4/U5/U6 triple snRNP results in U1 snRNP dissocation; U4 dissociates and U6 base pairs with U2 that is still bound to branch point 4) ATP is used int he first step of splicing (5' OH is cut, lariate is formed) 6) ATP is indirectly used in the second step of splicing (ligation) |
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U1 leaves before splicing occurs?
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Yes
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U1
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base pairs at 5' splice junction
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Helicase mediate arrangements?
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ANY TIME ATP IS USED IT's A HELICASE REACTION
5' splice site selection; helicase replaces U1 snRNP with U6 snRNP -Branch point site selection: replace BBP and U2AF with U2 snRNP snRNA rearrangements between 1st and 2nd step of splcing |
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Helicase
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uses ATP
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Three groups of ribozymes that are involved in self catalysis?
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Group 1 No lariat
Group 2/3 Lariats |
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Eukaryotic mRNAs must be capped spliced and polyadenylated?
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True
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Which pol recruits teh enzymes needed for 5' capping, splicing and 3' polyadenylation?
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Pol 2; it also transcribes the same time.
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why 5' cap first?
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5' cap is all you can do because we synthesize in 5' to 3' direction, read in 3' to 5'
to protect against the degradation, what else? because nothing else available |
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Phosph only at serine 5?
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means capped
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Diphosphorylated at 2 an 5
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means it is splicing
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Singly phosphorylated at 2
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means 3' end processing
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diphosphorylation at 2 and 5
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signals splicing proteins to be recrutied
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RNA Pol2 has a CTD (c terminal domain) that is important in the recruitment of the splisozomes and phophorylations? T/F
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True
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After CTD has formed proper structure and RNA is synthesizing what happens when AAUAAA sequence is recognized?
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the CPSF and CsTF bind to the poly adenylation signal sequence and the RNA is cleaved 10-30 nucleotides downstream of the AAUAAA sequence.
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What is poly A polymerase PAP?
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Poly A Polymerase adds about 200 A groups to the 3' mRNA piece
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Does any transcription that occurs after cleavage stay on?
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No it lacks 5' cap, and poly A tail
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Poly A binding protein
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coats the poly A to prevent the chewing by nucleases
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Alternate splicing increases proteome T/F?
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True
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Intron retention?
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occurs when a particular intron is not spliced (results in different translation)
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exon skipping
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occurs if splicing skips over one or more exons (very common)
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3' / 5' splice site selection
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1st intron/ 2nd intron
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Alternate splicing makes many proteins from one gene?
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True; that's why 25000 genes code for a shit ton of proteins
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Spinal Muscular Atrophy? What is it?
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Auto Rec degenerative motor neuron disease caused by homozygous mutation of survival motor neuron gene SMN1.
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SMN1 and SMN2 are important in the?
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biogenesis of snRNPs
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Mutation in motor neruon SMN1
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causes skipping of exon 7 because it replaces an exonic splicing enhancer with an exonic splicing silencer
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ESH vs ESS
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exon 7
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Exon skipping in Duchennes Muscular Dystrophy?
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T-->A mutation leads to a stop codon. Exon skipping leads to dystrophin retaining partial activity without mutated sequence from exon 31.
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eukaryotic initiation factors
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bind to mRNA freshly exiting into the cytosol...they help circulize the mRNA
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