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Lecture Topic 16
Transcription and RNA Processing
39
Biology
Undergraduate 1
11/26/2009

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Term
RNA is a __________________ molecule.
Definition
Single-stranded
Term
What are the 4 different structures of RNA?
Definition
Hairpin, Bulges, Internal Loops, and Pseudoknots
Term
Structure=_____________.
Definition
Function
Term
Transfer RNA (tRNA)
Definition
Reads codons in mRNA and transfer amino acids to growing polypeptide chains during protein synthesis.
Term
Catalytic RNA (Ribozymes)
Definition
Catalyze biochemical reactions in manner similar to protein enzymes.
Term
Ribosomal RNA (rRNA)
Definition
Structural components of RNA.
Term
Messenger RNA (mRNA)
Definition
Information in its nucleotide sequence that codes for a specific protein product.
Term
Transcription
Definition
Process of sunthesizing a strand of RNA that is complementary to one of the two strands of DNA.
Term
RNA Polymerase binds to the ____________.
Definition
Promoter.
Term
Promoter
Definition
Specific DNA sequence that seperates the DNA strands and sunthesizes a complementary strand of RNA.
Term
____________ replaces ____________ in RNA.
Definition
Uracil; Thymine.
Term
Transcription Unit
Definition
The stretch of DNA that is transcribed.
Term
A=____; G=______.
Definition
U;C
Term
In Eukaryotes, the transcription unit is _____________ and the RNA will code for _____________ polypeptide chain.
Definition
a single gene; a single
Term
What is the direction of transcription?
Definition
Downstream; 5 prime to 3 prime.
Term
Transcription Factors
Definition
An extensive set of accessory proteins that eukaryotes use that interact with the promoter and RNA polymerase to regulate transcription.
Term
What only have 1 RNA polymerase?
Definition
Prokaryotes.
Term
Terminator
Definition
In bacteria, this sequence ends the transcription process.
Term
When does transcription stop?
Definition
When transcription machinery reaches the end of a gene.
Term
In bacterial cells, what happens after mRNA transcription?
Definition
It is ready to be translated, no further modifications are needed.
Term
In Eukaryotes, what happens after mRNA is created?
Definition
Enzymes in the eukaryotic nucleus modify pre-mRNAs before they are transported to the cytoplasm where they are translated.
Term
Where do transcription and mRNA processing take place in Eukaryotes?
Definition
In the eukaryotic nucleus then translation takes place in the cytoplasm.
Term
Eukaryotic Polymerase 1
Definition
rRNA
Term
Eukaryotic Polymerase 2
Definition
mRNA
Term
Eukaryotic Polymerase 3
Definition
tRNA
Term
mRNA processing modifications
Definition
1. addition of cap to the 5' end
2. addition of Poly A tail to 3' end
3. removal of internal sequences called introns (RNA splicing)
Term
Where is the guanosine cap methylated at?
Definition
The 7th position of the purine ring.
Term
What does the Poly A tail do for the mRNA?
Definition
Portects the mRNA from degradation from the 3 end and used to help regulate mRNA stability.
Term
Intron
Definition
Intervening Sequence
Term
Exon
Definition
Expressed Sequence
Term
What is RNA splicing carried out by?
Definition
Spliceosomes.
Term
What are spliceosomes made of?
Definition
snRNP
Term
What are snRNP made of?
Definition
Small uracil-rich RNA and a unique set of 5-8 proteins.
Term
Which snRNPs are involved in RNA splicing?
Definition
U1,U2,U4,U5,U6
Term
Alternative mRNA Splicing
Definition
Some genes can encode more than one kind of polypeptide; it depends which segments are treated as exons during mRNA splicing patterns.
Term
What are the 4 types of alternative mRNA splicing?
Definition
1. exon skipping/inclusion
2. alternative 3' splice sites
3. alternative 5' splice sites
4. mutually exclusive exons
Term
The number of different proteins an organism can produce is _________________________________.
Definition
much greater than its number of genes.
Term
Human Gene Paradox
Definition
Before it was sequenced, estimates of how many genes were in the range of 100,000 or more. The project resulted in identification of only 20,000 genes.
Term
RNA splicing
Definition
the removal of introns and splicing together of remaining exons
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