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Presentation on theme: "RNA."— Presentation transcript:


2 History mRNA and tRNA worked out in the 1960s
Purification of RNA lead to 23S, 16S, and 4S species and accounted for 85% of all RNA tRNA accounted for about 15% of all RNA Hybridization experiments did not match DNA mRNA accounts for only 1-4% of RNA

3 Types of RNA mRNA tRNA rRNA snRNA snoRNA siRNA microRNA

4 Primary RNA mRNA (messenger RNA) rRNA (ribosomal RNA)
Transcribed from DNA Is then translated into protein rRNA (ribosomal RNA) Necessary for helping ribosomes make protein (catalysis) tRNA (transfer RNA) Mediates amino acid recognition with codons

5 Other RNA snRNA – small nuclear snoRNA – small nucleolar
microRNA – micro siRNA – short interfering These RNA species have a variety of functions and not all of them have been worked out yet.

6 RNA and Rfam Pfam is a database we discussed to determine groups of proteins Rfam is a similar database for families of RNA

7 tRNA and folding tRNA have a unique fold
There are multiple websites to determine RNA folding

8 Ribosomal RNA Has a structural and functional role in ribosomes
Prokaryotes: 70S which is 30S & 50S, which is 16S, 23S, 5S Eukaryotes: 80S which is 45S which is 18S, 28S, and 5.8S

9 snRNA Found in nucleus Involved with splicing and telomer maintenance
5 classes U1, U2, U4, U5, U6

10 snoRNA Modify both rRNA and snRNA 2 Classes C/D Box – methylate rRNA
H/ACA Box – convert uridine to peudouridine in rRNA

11 miRNA Recent discovery Small approximately 22 nucleotides
Function to down regulate protein expression.

12 RNAi (siRNA) Double stranded RNA Small, artificial
Degradation by RISC and Dicer Protective mechanism for plants and animals

13 mRNA Coding RNA Central Dogma “one gene – one protein”
No longer valid Alternative splicing, regulation, introns, etc. Altered expression by: Region, development, environment, disease, gene activity

14 mRNA Key research areas mRNA expression database
There is a DNA database, but is an mRNA database equally good? Potential problems with and mRNA database How to measure mRNA expression

15 mRNA expression Steady-state mRNA (polyA isolation)
Transcriptional control RNA processing control RNA export control RNA surveillance control

16 est database How to study mRNA Highly unstable, need to make cDNA
Turn mRNA into DNA with reverse transcriptase Clone into a vector Sequnce (this is called an express sequence tag EST) ESTs can be isolated from specific cells at specific times under specific conditions. This can aid in finding when types of proteins MAY be expressed

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