○ Synthesizes an mRNA complementary to template strand ■ A,U,C,G ● mRNA breaks off ○ Given 5’ cap and Poly A Tail ○ mRNA = RNA equivalent of the CODING strand ■ T’s are replaced with U’s ● End: mRNA The Basics of Translation: ● Start: mRNA (produced in transcription) ● mRNA leaves nucleus and travels to ribosome ● Ribosome binds to mRNA ○ Ribosomal binding site ○ Searches for AUG start codon ○ Finds the start codon and starts translating ● tRNA ○ Has sequences complementary to mRNA ○ tRNA sequences = anticodons ○ mRNA sequences = codons ■ Every 3 nucleotides = 1 codon ■ Every 1 codon = codes for 1 amino acid ○ tRNA has amino acids hanging off ■ Get added to polypeptide chain when the codon for it is read ■ When codon is read, tRNA binds complementary area ■ Releases amino acid ● A site of Ribosome: ○ Binds the tRNA’s that have amino acids on them ○ 1st site ● P site: ○ Binds the tRNA’s that are now bound to mRNA ○ Haven’t let go of their amino acids yet ● E site: ○ Releases amino acid from tRNA and joins it to peptide chain ● End: amino acid chain (polypeptide) AKA protein Final Exam Study Guide: Lecture 24: ● Gene Expression: ○ Expression: creation of the final functional products (protein or RNA) ○ Cell needs to control: ■ How many times transcription happens ■ At what rate it happens ■ When it happens ○ Recruiting RNA polymerase: ■ Must be recruited to the start of region of DNA to begin transcription ● Promoter: the “start” where the polymerase is recruited ○ Able to interact with polymerase ○ Facilitates dissociation of double helix ■ Something else must recruit it to the DNA
● General transcription factors do this recruiting ○ General Transcription Factors: ■ 1. Recognize specific sequence of DNA ■ 2. Bind to the RNA polymerase ● Promoters: ^* know order ○ Strength depends on its ability to produce transcript at a certain rate ○ 3 classes: ■ Constitutive: not regulated strongly, base state = “on” ● Strong constitutive : transcription relatively high ● Weak: transcription relatively low ■ Activated/Induced: respond to a stimulus to increase transcription ● Base state is “off” ■ Repressed : respond to stimulus to decrease transcription ● Base state is “on” ○ Transcription factors: the proteins that act as this stimuli for gene regulation ■ Bind specific DNA sequences (operatore) near the promoter ■ Activator: increases transcription ■ Repressor: decreases transcription ■ Positive/Negative Regulation: ● For Transcription Factors: only look at what happens to transcription ○ Represses transcription = negative regulator ■ Gene expression could still be affected positively ■ If it is removed, transcription continues ○ Increases transcription = positive regulator ■ If it is removed, transcription stops ○ Allosteric Modulators of Regulatory Proteins: ■ Stimulate the transcription factors ■ AKA inducers, co-repressors, or co-activators ●
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