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This text explores the Central Dogma of Biology, detailing how DNA encodes the instructions for protein synthesis. It highlights the processes of transcription (conversion of DNA to mRNA) and translation (mRNA to protein), explaining the roles of RNA, the significance of different alleles, and the impact of gene expression on our traits. The differences in protein makeup among individuals arise from variations in DNA and how genes are expressed. This informative piece provides a foundational understanding of how our genetic blueprint translates into the proteins that define us.
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Transcription and Translation The Central Dogma of Biology
How does DNA make us who we are? • By making proteins! • DNA contains the instructions for which proteins to make • *and complicated instructions on when to make them that we don’t fully understand
We Differ in our Protein Make Up • I.e. difference in pigments (hair, eye, skin etc.) • I.e. difference in enzymes (make different amounts of molecules) • I.e. difference in antibodies (some get sick more often or from different things) • *A lot of differences are also due to more complicated gene expression
Different Alleles • Code for slightly different versions of the protein • Probably arose through mistakes in DNA replication Makes a purple protein in flowers Makes a white protein in flowers
Transcription • DNA-> mRNA • Like making a copy of the blueprint • Kind of like DNA replication- complementary nucleotides are added- EXCEPT U is used instead of T
RNA vs. DNA DNA • Deoxyribose sugar • A,C, G and T nucleotides • Usually double stranded • Stores the code (like the master blueprint) • Ribose sugar • A, C, G and U nucleotides • Usually single stranded • But can fold on itself • Different types and functions • mRNA, tRNA, rRNA • Carries code, assembles proteins RNA
Where does it happen? • Each gene has a promoter • Transcription factors help RNA polymerase bind to the promoter and begin transcription
Example – promoter=TATAA RNA polymerase AGCTATAACGACG T TAGCATCA T CGATAT T GCT GCAATCGTAGT T CGATAT T GCT GCAATCGTAGT DNA GCUGCAAUCGUAGU mRNA
Mr. Mahon’s Pet peeve • DNA is not turned into RNA! • An RNA molecule is made based of the DNA code!
Translation • mRNA Protein in the ribosome
Basics of Translation • Every 3 RNA nucleotides (letters) codes for 1 amino acid • Called a “codon” • Example: DNA ATG GCA GAC RNA UAC CGU CUG Protein Tyr ArgLeu
How? • A tRNA molecule carries an amino acid • tRNA nucleotides must be complementary to mRNA code
Beginning and End • Translation always begins at the Start Codon AUG and ends when a STOP codonis reached • Ex. RNA GTCA AUG GCC CCA UGG • Protein Met – Ala - Pro
Review • Transcription • DNA (gene) transcribed to make mRNA which carries code • In Nucleus • Translation • mRNA code translated into a protein • With help of tRNA in the ribosome