Types of RNA mRNA: messenger RNA, carries the DNA code out of the nucleus to the ribosome tRNA: transfer RNA, carries amino acids to the ribosome rRNA: ribosomal RNA, part of the ribosome
Transcription (making RNA) 1.DNA unzips 2.one strand of DNA acts as a template 3.RNA polymerase reads the DNA bases 3’ to 5’ 4.RNA nucleotides are placed across from the complimentary DNA bases 5.RNA separates from DNA 6.DNA zips back up
mRNA processing 1.Methylated guanine cap added to 5’ end 2.Poly-A tail added to 3’ end of mRNA 3.Introns (non-coding RNA) are removed 4.Exons (coding RNA) are spliced together
mRNA Processing 5’ cap 3’ AAAAAAA “poly-A” tail Introns removed, exons spliced together http://www.arabidopsis.org/servlets/sv?action= accession&type=gene&id=2204897&chr=1 Click on this link and click on the sequence ruler to view genetic sequence with introns, exons etc.
Protein Synthesis or How to Make Your Own Proteins
mRNA: messenger RNA - single- stranded, brings the DNA message out of the nucleus. tRNA: transfer RNA – single-stranded but looped around to be shaped like a “t”. brings an amino acid to a ribosome to build a protein.
Transcription: making mRNA. RNA polymerase (enzyme) reads one strand of unzipped DNA, and makes mRNA using the order of the DNA bases. mRNA leaves the nucleus through the nuclear pores. In the cytoplasm, mRNA is read by ribosomes.
Translation: making proteins from the mRNA code.
mRNA enters a ribosome. One tRNA molecule brings one amino acid to the ribosome. Another tRNA brings another amino acid and the 2 amino acids form a peptide bond. The first tRNA leaves the ribosome and the 2 nd tRNA shifts over. This growing polypeptide chain will become a protein.