Cell Division, Genetics, Molecular Biology 20.2 Gene Expression Transcription/Translation Protein Synthesis

Amino Acids Frederick Sanger 1952: - proteins consist of __________ of molecules called amino acids - specific sequence of ________ _______determines chemical properties of each protein - proteins produced by cell determine __________, ________ & ______________ of cell Proteins responsible for ____________ traits Sequence of _________ _________ in DNA makes up genetic code of organism Genetic code determines how amino acids strung together (how proteins are made)

Genetic Code In a gene: each set of 3 bases is a _________ Genetic code always ____________ in terms of _________ codon rather than original DNA sequence Each mRNA codon ________ for a specific ________ ______ Only 20 amino acids found in proteins, depend on combination of bases in codon _________ and __________ codons initiate or terminate protein synthesis

Ex) A U G C U U A A A G C C U G A

Gene Expression Way information in a gene is _________ into a specific trait through production of a _____________ (protein) - products of all genes = polypeptides ___________ is utilized to convert ______ into ________ - __________ RNA (mRNA) - __________ RNA (tRNA) - __________ RNA (rRNA) 2 stages of gene expression: __________ and ___________ Transcription: genetic information converted from ______ __________ into mRNA, __________ information from _______ to __________ Translation: genetic _________ from mRNA used to _________ polypeptide chains of specific amino acids

Gene Expression Central Dogma: 2 step process of ________ genetic information from ________ to ________, then from ________ to _________

Transcription Overview DNA sequence _________ (transcribed) into the ________ of a _______ stranded ________ molecule THREE PROCESSES: 1. Initiation: RNA ________ binds to DNA at _______ site near ________ of gene 2. Elongation: RNA polymerase uses DNA as _______ to build ____________ molecule 3. Termination: RNA polymerase ______ the end of ______ and ________ mRNA then _________ from template strand _________ through _________ pores, into _________ of cell

Transcription – Initiation Only one strand of the double-stranded DNA is ____________ for each gene - template strand: one that is transcribed - _______ strand can serve as the _________ strand for different genes ________ _____________ binds to segment of DNA - ________ double helix - binds in front of _______ to be transcribed

Transcription - Elongation DNA strand to be transcribed = template RNA _________ moves along template strand of DNA and begins _________ __________ in 5’ to 3’ direction mRNA strand _____________ to DNA template strand EXCEPT _________ is _________ with ____________

Transcription - Termination RNA polymerase reaches _____ of ________ Termination sequence: RNA polymerase ___________ it as end Transcription stops, mRNA ______________ from DNA template strand RNA polymerase free to bind to another promoter site - transcribe another gene mRNA free and _________ out of nucleus into cytoplasm

Review Transcription

Translation Overview mRNA now in the __________ needs to be _________ - puts _______ __________ together according to genetic information and creates ________ ____________: site of translation - composed of 2 subunits: ________ together around mRNA, ________ ______ mRNA THREE PROCESSES: 1. Initiation 2. Elongation 3. Termination

Translation - Initiation Occurs when _____________ recognizes specific sequence on mRNA – ______ to it Ribosome _______ along mRNA in 5’ to 3’ direction - ____ amino acids to polypeptide chain once it reads a ________ Must start reading in correct ________ on mRNA - _________ codon (AUG) - ensures ribosome ______________ code using reading frame of mRNA molecule - results in _________ sequence of amino acids __________ RNA (tRNA) carries amino acids back to ribosome structure of tRNA contains an _________________ - ___________ to _________ of mRNA - tells tRNA which amino acid to bind to - amino acid _________ to opposite end - tRNA ___________ amino acid to ribosome

tRNA Structure

Translation - Elongation Start codon recognized by ribosome - codes for _____________ 2 sites for tRNA to attach - A (aminoacyl) - P (peptidyl) tRNA with anticodon complementary to start codon _______ P site Next tRNA carrying required amino acid enters the _______ site - peptide bond formed between both amino acids Ribosome _____________ over one codon so that _________ tRNA is now in P site _________ first tRNA from P site and allowed THIRD tRNA to enter ___________ A site - like a tickertape! Released tRNA’s __________ back into cytoplasm

Translation - Termination Ribosome reaches one of THREE ______ CODONS - UGA, UAG, UAA Do not _______ for an amino acid, no ____________ tRNA’s Protein release _______ recognizes that ribosome has stalled and helps release _____________ chain from ribosome TERMINATION. Translation Transcribe & Translate!