Please enable JavaScript.
Coggle requires JavaScript to display documents.
Gene Expression at the Molecular Level - Coggle Diagram
Gene Expression at the Molecular Level
Overview
Gene Function
Molecular function of protein
Organism’s traits determined by proteins
Central Dogma: DNA → RNA → Protein
Gene Types
Structural genes (polypeptides)
Non-coding genes (tRNA, rRNA)
Transcription
Initiation
DNA strands separate (open complex formation)
Promoter recognition (sigma factor in prokaryotes)
Elongation
RNA polymerase synthesizes RNA (5’ → 3’)
Uracil replaces thymine
Termination
RNA transcript is released
RNA polymerase reaches terminator sequence
RNA Processing (Eukaryotes)
5’ Capping
Modified guanosine for stability and ribosome binding
3’ Poly-A Tail
100-200 adenines for mRNA stability
Splicing
Alternative Splicing (different mRNA products)
Spliceosome (snRNPs)
Introns removed, exons joined
Translation and the Genetic Code
Start Codon: AUG (Methionine)
Stop Codons: UAA, UAG, UGA
Codons (3 nucleotide sequences)
Degeneracy: Multiple codons for same amino acid
The Machinery of Translation
Components
tRNA: Carries amino acids, anticodon recognition
mRNA: Carries codon sequence
Ribosomes: Catalyze polypeptide synthesis
Translation Factors: Assist in various stages
Ribosomal Sites
P Site: Peptidyl site (growing chain)
E Site: Exit site (uncharged tRNA exits)
A Site: Aminoacyl site (new tRNA)
Stages of Translation
Elongation
Codon recognition and peptide bond formation
Ribosome shifts (translocation)
Termination
Stop codon recognition by release factors
Polypeptide released, ribosome disassembles
Initiation
mRNA, tRNA, ribosomal subunits assemble
GTP provides energy