RNA synthesis
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What is transcription?
Process of RNA synthesis from a DNA template
What is the central dogma?
DNA -> RNA -> Protein
What are the four RNA types?
mRNA tRNA rRNA Noncoding RNAs
What is mRNA?
Codes for proteins, makes uo 3 to 5% total RNA
What is tRNA?
participates in translation, there are 49 families, each carries an amino acid and has a specific anticodon loop
What is rRNA?
ribosomal RNA, major constituent of ribosomes, There are 4 main types
What are noncoding RNAs?
Serve as structural and enzymatic functions
What are the four major differences between RNA and DNA?
1) Contains ribose instead of deoxyribose 2) Contains U instead of T 3) Synthesised as a new strand 4) RNA is very unstable
What is the structural difference between deoxy-ribose and ribose?
Deoxyribose does not have an OH group at C3, just has a H
Which bases pair up in RNA?
U = A G = C
What is non Watson Crick pairing and can it occur in RNA
Where the pairs do not pair according to the watson crick rule ie G = U Yes it can occur
What is the secondary structure of RNA like?
It forms stem-loop secondary structures
What is RNA tertiary structure?
Where the RNA folds into a three dimensional shape
What are RNA polymerases?
The enzymes which perform RNA synthesis There are 3 types in eukaryotes
What are the 3 types of RNA polymerases?
RNA polymerase I, II and III
What is RNA polymerase I?
only transcribes ribosomal RNA Accounts for 50% of RNA polymerases
What is RNA polymerase II?
Protein encoding genes Transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA
What is RNA polymerase III?
The genes transcribed are”housekeeping” genes Regulation primarily tied to the regulation of cell growth and the cell cycle eg tRNA, small nuclear RNA and 5S rRNA
Which rRNA does RNA polymerase I not transcribe?
5s rRNA
True or false - only one RNA polymerase molecule can bind to a gene at anyone time
False - multiple RNA polymerases can bind on the same gene
Is a primer needed for RNA synthesis?
No
How many strands are used as a template for RNA synthesis?
Only one strand is used
Does the RNA transcript remain bound to the DNA template?
No
Describe an issue with RNA synthesis compared to DNA synthesis
There is a much higher error rate