Transcription & Translation Protein Synthesis Biology 12
In nucleus Produced in nucleus Travels to cytoplasm Produced in cytoplasm Central Dogma
Task • Complete the following table:
Task Transcription & Translation • Using pages 239/240 • Make notes for EACH about: • Initiation (how it starts) • Elongation (how it is built) • Termination (how it ends)
Transcription ‘to copy’ Initiation: • RNA polymerase binds to DNA @ ‘promoter’ Elongation: • RNA polymerase builds mRNA • From DNA 3’ end • Uses complimentary base pairing • Remember: thymine (T) is replaced by uracil (U)
Transcription ‘to copy’ Termination: • RNA polymerase reaches end of gene • Stops transcribing End Result: • mRNA breaks away from DNA • mRNA exits nucleus
Translation ‘new language’ Initiation: • Ribosome binds to start codon Elongation: • Ribosome moves along mRNA • From mRNA 5’ end • 3 nucleotides = codon = amino acid • tRNA delivers proper amino acid Turn to page 240!
Translation ‘new language’ Termination: • Ribosome reaches stop codon • Stops translating End Result: • Ribosome falls off mRNA • Protein (polypeptide chain) is released
Start and Stop Codons Start Codon: • Begins translation • AUG (universal start codon) • ALSO Codes for methionine (Met) • Sometimes GUG or UUG Stop Codon: • Ends translation • UGA, UAA, UAG Page 240!
Transfer RNA (tRNA) • Delivers amino acid to ribosome • Reads mRNA codon • Has a matching ‘anticodon’ • One tRNA for each amino acid
The Whole Picture Next amino acid to be added to polypeptide Growing polypeptide tRNA mRNA
Example • DNA template: 3’ TAC ACA CGG AAT GGG TAA AAA ACT 5’ • Complimentary DNA • Read from DNA template (start reading at 3’) • mRNA codon • Read from DNA template (start reading at 3’) • tRNA anticodon • Read from mRNA • Amino Acids (protein) • Read from mRNA
Who’s who? Mr. Na mRNA Meri Boso ribosome Flash cards tRNA Translation protein United Nations Conference
Task • # 2, 4 – 6, 9 – 11 (page 241) Omit “ribosomes” for #4 • # 2 (page 249) • # 3, 4 & 6 (page 254) DNA rules!
Task A:#2 – Central Dogma • DNA makes RNA (mRNA) • through transcription • RNA makes proteins • through translation
mRNA Messenger RNA End product of transcription Takes message from DNA into cytoplasm Used by ribosome to make protein tRNA Transfer RNA Delivers amino acid to ribosome rRNA Ribosomal RNA Helps form and maintain ribosomes #4 – RNA types
DNA Sugar – deoxyribose Double stranded Base pair – thymine Stays in nucleus Can replicate itself Longer strands RNA Sugar – ribose Single Stranded Base pair – uracil Can leave nucleus Cannot replicate itself Shorter strands #5 – DNA vs. RNA
Transcription Purpose: To make mRNA from DNA Location: Nucleus Translation Purpose: To make a specific protein from mRNA Location: Cytoplasm (ribosome) #6 – Transcription/Translation
Start Codon mRNA code Tells ribosome to begin translation Example: AUG Also codes for methionine And: UUG, GUG Stop Codon mRNA code Stops translation of that specific amino acid chain Examples: UAA, UAG, UGA #9 – Stop vs. Start Codon
#10 – Transcribe to mRNA • DNA: GGA TCA GGT CCA GGC AAT TTA GCA TGC CCC AA • *mRNA*: CCU AGU CCA GGU CCG UUA AAU CGU ACG GGG UU
#11 – Translate to Amino Acids • mRNA sequence divided into codons: GGC AUG GGA CAU UAU UUU GCC CGU UGU GGU GGG GCG UGA • *Protein translation*: Gly Met(start) Gly His Tyr Phe Ala Arg Cys Gly Gly Ala (stop)
Task B:#2 – Transcribe to mRNA • DNA: TAC TAC GGT AGG TAT A • *mRNA*: AUG AUG CCA UCC AUA U
#4 – Change in 3rd Base May Not Result in Error • Why not? • Amino acids have more than one codon • Example: proline • Codons CCU, CCC, CCA, and CCG • CC - always codes for proline • Third base/nucleotide does not matter
#6 – Translate to Amino Acids • mRNA: GGC CCA UAG AUG CCA CCG GGA AAA GAC UGA GCC CCG • *Protein translation*: Met (start) Pro Pro Gly Lys Asp (stop)