Types of RNA and TRANSCRIPTION

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 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

Process of Transcription Transcription- process that makes mRNA from DNA Definitions: Upstream promoter template strand Coding strand 5’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

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

Transcription

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

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

  Ribosome tRNA Lysine tNA mRNA mRNA Ribosome Translation direction