DNA transcription & translation

Ribosome

Transcription

Synthesis of mRNA from DNA

Translation

Synthesis of polypeptides via RNA

RNA polymerase

Pries double helix apart

Reads 1 DNA strand

Adds nucleotides to RNA

Promoter sequences AKA tata box

Promotes signal initiation of RNA synthesis

Transcription factors

Help RNA polymerase find promoter sequence

Transcription elongation

RNA polymerase moves along DNA, matches RNA nucleotides with DNA template

Transcription termination

Polyadenylation sequence is transcribed by RNA polymerase, proteins cut mRNA free and polymerase falls off DNA

RNA processing

pre-mRNA receives a nucleotide cap at the 5’, and the 3’ gets a poly-a tail (which help ribosomes attach in the cytosol)

Introns

Non-coding

Extrons

Expressed

snRNP

Recognize splice sites

Ribozymes

Catalytic RNA molecules, splices RNA

Codons

Triplet sequences of nucleotides along mRNA

Amino acid base number

3

tRNA

Shuttles amino acids to building polypeptide

Has anticodon that binds to mRNA codon

Aminoacyl-tRNA synthetase

Joins amino acids to the tRNA to activate it

Ribosomes

Facilitate coupling of tRNA anticodons with mRNA codons during protein synthesis

Translation initiation

Start codon and initiator tRNA (Met) bind → subunits of ribosome join

Translation elongation

Amino acids are added one by one to the polypeptide

Termination

Ribosome reaches a stop codon on the mRNA, and release factor causes the ribosome and tRNA to fall away

Protein for export

Then ribosome with mRNA is drawn to the ER by signal recognition pattern (SRP)

Epigenetics

Chemical mechanisms that control the expression of genes

Histones

Control longer sections

Methylation

Repressors