Translation
Gene Expression transfer of genetic info from DNA to RNA to protein
|
Codons mRNA is read in groups of 3 nucleotides. Codes for amino acid
|
Transfer RNA (tRNA) single stranded RNA of 80 nucleotides. Bonds to amino acids and mRNA codon
|
Ribosomes catalyzes the peptide bonds between amino acids
|
1) INITIATION eukaryotes, ribosome small subunit recognizes and binds to the mRNA at the 5’ cap. Initiator tRNA attaches at AUG codon
|
Ribsomal binding sites 1 site where mRNA binds, 3 sites where tRNA binds (A site - aminoacyl-tRNA site...... P site - peptide-tRNA site...... E site exit site, leaves the ribosome)
|
2) ELONGATION initiator tRNA binds to ribosome, incoming tRNA binds to A site. H bonds form between mRNA codon and tRNA anticodon. Requires GTP (E)...... Peptide bond formed between A site and P site by ribosomes = longer peptide chain
|
3) TERMINATION At stop codon, a protein release factor binds to A site. (Adds H2O instead of amino acid, polypeptide chain is released)
|
Polysome single strand of mRNA can be used to make multiple copies of a polypeptide simultaneously
|
Polysome single strand of mRNA can be used to make multiple copies of a polypeptide simultaneously
|
|
|
History
Friedrich Miescher discovered DNA. White blood cells from pus- isolated nuclei (high in P)
|
Frederick Griffith studied bacteria that caused pneumonia (used Rough and Smooth Strains)- defined it as transformation in cell's function
|
Avery, LcLeod, and McCarty purified S strain bacteria, added it to R strain bacteria. No S cells appeared in the tube w/ no DNA, but they did appear in that w/ no proteins and no RNA
|
Hershey & Chase used bacteriophage to infect bacteria. Light up DNA and Protein case, only DNA was passed to bacteria.
|
DNA Replication
Replication Origin Specific sites where replication begins, then bidirectional. (can be more than one)
|
Helicase enzyme that disrupts H bonds, creating replication fork
|
Single Stranded Binding Proteins relieve pressure. bind to unwound single stranded DNA to keep strands apart
|
Topoisomerases relieve pressure. break bonds in DNA then reform them.
|
RNA Polymerase adds primer (RNA nucleotides)
|
Priming Required as DNAP (DNA Polymerase) can only add nucleotides, but RNAP can start a new chain.
|
DNA Polymerase III adds nucleotides to the 3' end of pre-existing nucleotides. (hydrolyzes last two phosphate groups)
|
Leading Strand synthesized continuously, moving along replication fork
|
Lagging Strand synthesized in short, discontinuous segments of 1000-2000 nucleotides (Okazaki fragments)
|
DNAP I replaces RNA primer with DNA
|
DNA Ligase joins broken pieces of DNA by catalyzing formation of phosphodiester bonds
|
DNAP III can correct errors as it moves down the strand
|
DNAP II checks for errors and corrects them
|
|
|
Transcription
Archibald Garrod studied patients w/Alkaptonuria (pee turns black with O2), faulty genes meant they couldn't break down alkapton (no enzyme)
|
George Beadle & Edward Tatum bread mould, using x-rays to create mutations- and then the moulds couldn't grow
|
Central Dogma TRANSCRIPTION (DNA- mRNA) nucleus TRANSLATION (mRNA- protein) ribsomes The Flow Of Info
|
1) INITIATION RNAP binds to promoter. Composed of TATA box (less energy to break H bonds) RNAP recognizes the promoter and begins unwinding DNA
|
2) ELONGATION RNA polymerase unwinds, exposing 10-20 base pairs. Uses template strand to add complementary RNA nucleotides, from 5' to 3'
|
3) TERMINATION Prokaryotes: protein, mRNA binds to itself (hairpin) Eukaryotes: many A's = many U's added = weak=proteins bind
|
Multiple Transcription Machinery multiple RNAP can transcribe simultaneously on the same gene
|
Post-Transcriptional Modifications in prokaryotes mRNA can be used directly, in eukaryotes it needs to be modified (pre-mRNA to mature mRNA) in order to leave the nucleus
|
mRNA Modifications- capping poly(A) tail - 50-250 adenine added to 3' end, preventing degredation --------- 5' cap 7 G's added to prevent degradation, signals for ribosomes to attach
|
mRNA Modifications- splicing removal of introns (non-coding regions) & mature mRNA will only contain exons. Occurs in spliceosome (snRNPs bind to splice sites, excises introns, rejoins exons)
|
|
Created By
Metadata
Favourited By
Comments
No comments yet. Add yours below!
Add a Comment
Related Cheat Sheets
More Cheat Sheets by emilyaltmann