* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download You Light Up My Life
Gel electrophoresis of nucleic acids wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Transcription factor wikipedia , lookup
Molecular cloning wikipedia , lookup
Gene regulatory network wikipedia , lookup
List of types of proteins wikipedia , lookup
RNA silencing wikipedia , lookup
Community fingerprinting wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Bottromycin wikipedia , lookup
Molecular evolution wikipedia , lookup
Non-coding DNA wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Polyadenylation wikipedia , lookup
Promoter (genetics) wikipedia , lookup
Eukaryotic transcription wikipedia , lookup
RNA polymerase II holoenzyme wikipedia , lookup
Biochemistry wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Point mutation wikipedia , lookup
Silencer (genetics) wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Non-coding RNA wikipedia , lookup
Transcriptional regulation wikipedia , lookup
Gene expression wikipedia , lookup
Messenger RNA wikipedia , lookup
Expanded genetic code wikipedia , lookup
Genetic code wikipedia , lookup
Transfer RNA wikipedia , lookup
From DNA to Proteins Occurs in the nucleus DNA transcription Proteins are coded for by Genes- long stretches of DNA that code for a particular amino acid sequence Occurs in the cytoplasm RNA translation PROTEINS in-text, p. 201 Steps from DNA to Proteins Same two steps produce ALL proteins: Example: insulin from pancreas 1) DNA is transcribed to form RNA –Occurs in the nucleus –mRNA moves into cytoplasm 2) RNA is translated to form polypeptide chains, which fold to form proteins Three Classes of RNAs • Messenger RNA – Carries protein-building instruction • Ribosomal RNA – Major component of ribosomes • Transfer RNA – Delivers amino acids to ribosomes A Nucleotide Subunit of RNA uracil (base) phosphate group sugar (ribose) Base Pairing During Transcription • A new RNA strand can be put together on a DNA region according to basepairing rules (What enzyme?) • As in DNA: C pairs with G • Uracil (U) pairs with adenine (A) Promoter • A base sequence in the DNA that signals the start of a gene • For transcription to occur, RNA polymerase must first bind to a promoter Terminator Gene Transcription mRNA transcript Where is the promoter? Adding Nucleotides 5’ growing RNA transcript 3’ 5’ 3’ direction of transcription Transcript Modification unit of transcription in a DNA strand 3’ exon intron exon transcription intron 5’ exon into pre-mRNA poly-A tail 3’ cap 5’ snipped out snipped out 5’ 3’ mature mRNA transcript Code Is Redundant • Twenty kinds of amino acids are specified by 61 codons • Most amino acids can be specified by more than one codon • Six codons specify leucine – UUA, UUG, CUU, CUC, CUA, CUG tRNA Structure codon in mRNA anticodon in tRNA amino acid tRNA molecule’s attachment site for amino acid OH Ribosomes tunnel small ribosomal subunit large ribosomal subunit intact ribosome Initiation • Initiator tRNA binds to small ribosomal subunit • Small subunit/tRNA complex attaches to mRNA and moves along it to an AUG “start” codon • Large ribosomal subunit joins complex Binding Sites on Large Subunit binding site for mRNA P (first binding site for tRNA) A (second binding site for tRNA) Elongation • mRNA passes through ribosomal subunits • tRNAs deliver amino acids to the ribosomal binding site in the order specified by the mRNA • Peptide bonds form between the amino acids and the polypeptide chain grows Elongation Termination • A stop codon in the mRNA moves onto the ribosomal binding site • No tRNA has a corresponding anticodon • Proteins called release factors bind to the ribosome • mRNA and polypeptide are released Polysome • A cluster of many ribosomes translating one mRNA transcript • Transcript threads through the multiple ribosomes like the thread of bead necklace • Allows rapid synthesis of proteins What Happens to the New Polypeptides? • Some just enter the cytoplasm • Many enter the endoplasmic reticulum and move through the cytomembrane system where they are modified Transcription mRNA Mature mRNA transcripts Translation rRNA ribosomal subunits tRNA mature tRNA Gene Mutations Base-Pair Substitutions Insertions Deletions Effect of Base-Pair Substitution original base triplet in a DNA strand a base substitution within the triplet (red) As DNA is replicated, proofreading enzymes detect the mistake and make a substitution for it: POSSIBLE OUTCOMES: OR One DNA molecule carries the original, unmutated sequence The other DNA molecule carries a gene mutation Frameshift Mutations • Insertion – Extra base added into gene region • Deletion – Base removed from gene region • Both shift the reading frame • Result in many wrong amino acids Frameshift Mutation mRNA PARENTAL DNA amino acid sequence ARGININE GLYCINE TYROSINE TRYPTOPHAN ASPARAGINE ARGININE GLYCINE LEUCINE LEUCINE GLUTAMATE altered mRNA BASE INSERTION altered amino acid sequence