1. Functions of RNA mRNA (messenger)- instructions protein
tRNA (transfer) - carriers that match amino acids to codons during translation
rRNA (ribosomal)- part of the ribosomes- ribosomes are RNA plus proteins
snRNA's (small nuclear) - part of spliceosomes- that edit mRNA's
siRNA’s (small interfering) control gene expression.
Information storage is apparently only function of DNA. RNA has many other functions. Some even argue that the molecular antecedent of living cells – the “ancestral molecule” - may have been RNA.

2. The “central dogma” of molecular biology
DNA replication
transcription
mRNA
translation
protein

3. What is a “gene”?
“The genetic information that codes for a particular kind of protein”. However…
Some “genes” code for RNA molecules that have other functions (are not mRNA)
Some “genetic elements” are never transcribed into RNA or translated but still do important things, like control gene transcription
Also- some stretches of DNA are part of more than one gene in the sense that they code for parts of more than one kind of protein

4. Transcription Synthesis of RNA using DNA as a pattern
Promoter sequence at beginning and terminator sequence at end of transcription unit (why not call it a gene?)
RNA polymerases- (3 different ones in eukaryotes)
Only template strand of DNA is transcribed
“transcription unit” because the transcript includes a lot of extra base pairs that will be edited out, leaving the gene.

5. Transcription (see fig 12.5 in Brooker)
Promotor
RNA polymerase
Terminator
Transcription unit
“raw” RNA transcript

6. mRNA processing in eukaryotes
Pre-mRNA (the raw transcript) is modified before leaving nucleus
GTP cap and poly-A tail (a long string of adenosines) are added to 5’ and 3’ ends

7. mRNA processing, continued
Non-coding introns are removed and the remaining exons are spliced together.

8. Correspondence between exons and protein domains

9. Translation (protein synthesis)
mRNA has the pattern (the codons)
tRNA’s (transfer RNA) deliver the amino acids and match anticodon to codon
Ribosomes are where this happens. Catalyze formation of the peptide bonds.
Aminoacyl tRNA synthetases reload the tRNA’s with matching amino acids

10. Three different representations of tRNA molecules

11. Different tRNA for each kind of amino acid
Anticodon

12. “Activating enzymes” (aminoacyl-tRNA-synthetases) load each amino acid on it’s correct tRNA molecule. Requires ATP

13. Different synthetases for each kind of tRNA & amino acid

14. Ribosome E,P, and A are Binding sites for three tRNA molecules
A is for Amino acid +tRNA binding site
E is for “Exit”site
E,P, and A are Binding sites for three tRNA molecules
P is for Peptide+tRNA binding site

17. The initiation of translation

18. The elongation cycle of translation

19. The termination of translation

20. Polyribosomes

21. Coupled transcription and translation in bacteria

22. A summary of transcription and translation in a eukaryotic cell