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

2. 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)

3. 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

4. Ex) A U G C U U A A A G C C U G A

5. 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

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

7. 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

8. 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

9. 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 ____________

10. 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

11. Review
Transcription

12. 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

13. 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

14. tRNA Structure

15. 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

17. 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!