1. Types of RNA and TRANSCRIPTION

2. What are the differences between DNA and RNA ?
RNA: ribonucleic acid
Differences from DNA:
different sugar (ribose)
single stranded
3 types
Shorter than DNA
different base
(no thymine but URACIL instead)

3. 3 Types of RNA:
Messenger RNA: (mRNA) carries nucleotide sequence from nucleus to ribosome
Transfer RNA: (tRNA) picks up amino acid in cytoplasm and carries them to ribosome
Ribosomal RNA: (rRNA)found in ribosome, joins mRNA and tRNA; forms protein

4. Process of Transcription
Transcription- process that makes mRNA from DNA
Definitions:
Upstream promoter template strand
Coding strand ’cap poly A tail
Exon intron primary transcript
mRNA transcript terminator sequence
Stages –Initiation, Elongation, Termination
Initiation
RNA polymerase binds to DNA promoter and unzips it upstream of gene
Elongation
RNA polymerase builds single stranded RNA in 5’-3’ direction using the DNA template strand

5. Termination
RNA polymerase stops transcribing when it gets to the terminator sequence (forms PRIMARY TRANSCRIPT)
Postranscriptional Modifications
Eukaryotic DNA requires a 5’ cap at start of transcript?
Poly AAA tails is added at end of transcript?
Introns are removed via spliceosome

6. Transcription

7. Translation
Conversion of RNA into amino acid sequence that makes a protein
The mRNA leaves the nucleus and enters the cytoplasm
Ribosomes attach to mRNA
tRNA (carrying anti-codon) picks up the correct amino acids and carries them to the mRNA strand forming the protein
Ex:
tRNA carries GAU (anti-codon)& looks for CUA on mRNA

9. Translation mRNA tRNA mRNA Nucleus Lysine Phenylalanine Methionine
Ribosome
mRNA
Start codon

10. Ribosome
tRNA
Lysine
tNA
mRNA
mRNA
Ribosome
Translation direction