Transcription Creation of RNA (ribose nucleic acid)

Differences between DNA and RNA Deoxyribose (without oxygen) Ribose Double stranded Single stranded Thymine – adenine Uracil – adenine

Main Points Only transcribe 1 section of DNA at a time Small segments (depends on cells/bodies needs) Replace T with U 3 types of RNA mRNA: messenger RNA  makes proteins tRNA: transfer RNA brings amino acid to ribosome rRNA: ribosomal RNA  makes up ribosomes

Nucleus A T T G C C A A G C A U U G C C U U G C G T A A C G G T T C G DNA strand already transcribed is re-zipping Open segment of DNA  opened by enzyme A T T G C C A A G C A U U G C C U U G C G T A A C G G T T C G C U A Growing strand of mRNA DNA stranded opening for transcription Nucleus

Translation Reading of mRNA to make proteins for cell use Occurs in the cytoplasm with ribosomes

Nucleus Cytoplasm mRNA A U G C C A U U C G A U A G C U A A Step 1: mRNA moves into the cytoplasm to find Ribosome mRNA A U G C C A U U C G A U A G C U A A Nucleus Cytoplasm

Translation Ribosome attaches to start of mRNA (AUG) Bases are read in three’s (triplet codon)  codes for 1 amino acid Ribosome reads triplet condon  sends signal for correct tRNA (anti-codon that matches triplet codon)  tRNA brings the correct amino acid As ribosome moves down mRNA, each new tRNA accepts growing protein (polypeptide chain) Upon reading STOP codon, ribosome releases mRNA and protein mRNA may be read again or thrown away Protein moves onto its job

Cytoplasm ribosome Moves along mRNA until hits STOP codon tRNA leaves when it has transferred the protein chain to the next tRNA ribosome Moves along mRNA until hits STOP codon Growing protein chain tRNA Ribosome attaches to first codon Anti-codon A A G C U A A U G C C A U U C G A U A G C U A A Upon hitting STOP codon, ribosome breaks apart and protein is released Triplet codon: codes for 1 amino acid 1 mRNA can make multiple copies of a protein