Transcription and Translation - Lecture Notes | BICH 303, Study notes of Biology

Download Transcription and Translation - Lecture Notes | BICH 303 and more Study notes Biology in PDF only on Docsity! RNA Transcription and Translation How is information in DNA used to make protein? RNA acts as a messenger between DNA and protein synthesis machinery Transcription - copying of DNA sequence into RNA, complementary Translation - production of protein based on RNA sequence Whole process = gene expression DNA (gene) RNA Protein dAMP DNA uses deoxyribose sugar RNA uses ribose sugar AMP GMP UMP CMP In RNA uracil is used instead of thymine as a pyrimidine base RNA Ribonucleic Acid RNA Ribonucleic Acid Six kinds of RNA transfer RNA (tRNA) ribosomal RNA (rRNA) messenger RNA (mRNA) small nuclear RNA (snRNA) micro RNA (miRNA) small interfering RNA (siRNA) - carries individual amino acids during protein synthesis - is complement of DNA - encodes protein sequence Transcription Central dogma of molecular biology DNA (gene) RNA Protein Transcription: the synthesis of RNA based on DNA sequence Transcription RNA polymerase - reads DNA template and makes RNA - reads template strand of DNA in 3’ - 5’ direction - resulting RNA is complement of template strand - resulting RNA is same as coding strand (A to U) Translation Steps of translation: - initiation - elongation - termination How to read the sequence of mRNA? How does the sequence of mRNA translate into protein sequence? Translation The genetic code Genetic code is: - triplet of nucleic acids, 3 nucleic acids code for one amino acid - non overlapping - continuous, not interrupted by “commas” - universal, conserved among all known life Translation Codon - triplet of nucleotide bases that specifies a single amino acid Since 4 different nucleotide bases (A T G C ) there are 43 (=64) possible codons There are 20 different amino acids - multiple codons encode for a single amino acid ATG TTT TCT CCG AAT AGC GGT TGA DNA sequence: transcription AUG UUU UCU CCG AAU AGC GGU UGA mRNA sequence: translation Met Phe Ser Pro Asn Ser Gly stop AAAAAAAAAAAAAA AUG UUU UCU CCG AAU AGC GGU UGA 1. Initiation: Ribosome binds to mRNA and moves along until it recognizes 2. tRNA with bound amino acid binds to mRNA codon. - anticodon: - nucleotide bases in the tRNA - the complement of mRNA codon XXX 3. Elongation: Next tRNA binds to 4. Ribosome moves on to next codon, process repeats 5’ 3’ 5. Termination: polypeptide chain is terminated when Translation Met AAA Phe AGA Ser Met Phe Ser Pro Asn Ser Gly Robert W. Holley tRNA Discovery - American born biochemist - worked at Cornell University - finalized the structure of tRNA in 1964 - awarded Nobel prize in physiology or medicine 1968 along with Nirenberg and Khorana VC Translation Translation movie: YT Translation The Big Picture - what have we studied so far? Amino acids: - structure - acid/base properties - peptide bond Proteins: - 1˚, 2˚, 3˚, 4˚ structure - fibrous proteins - globular proteins - purification/analysis techniques - enzyme kinetics - mechanisms of enzyme control DNA: - structure - replication Transcription: - RNA polymerase - mRNA production Translation: - Ribosome - tRNA - a.a.’s linked to make protein Historically, this is the path of determining the central dogma of biological chemistry How to go from DNA base pair sequence to protein amino acids sequence.