Neil deGrasse Tyson on scientific literacy
Ames test culture media prep
Add E. coli test strain to plates
Add test disc to bacterial plate
Watch bacteria (Pseudomonas syringae) turn water into ice > story from Boing Boing
Wildlife crossing in Banff National Park. Story on CBC Quirks & Quarks
Douglas Rushkoff explains “Present Shock”
Rushkoff is the author of Present Shock: When Everything Happens Now
For discussion: Genetic Roulette | A film by Jeffrey Smith.
Academics Review has a detailed critique of the anti-GMO claims presented in the film.
BioFortified has an ongoing collection of peer-reviewed scientific publications on the risk of genetically engineered plants.
Los Rios Community College District is serious about student success! (And Star Trek)
Now you can understand how tides work - The Bay of St Brieuc in Brittany has one of the largest tides on Earth. Andrew Steele takes some time out of his holiday, on the day of the highest tide of the year, to find out why.
Thanks to @ARCNewsToday
Photo: Wikimedia Commons
BIOT307 (Biotechnology and Society) student question: Do a large percentage of proteins have methionine as the first codon?
Most coding sequences start with AUG, which means the first amino acid is methionine. So you can find many proteins with methionine as the first amino acid in the protein sequence.
Another process that can happen is that after translation occurs, the protein sequence can be modified. For example, methionine and other amino acids may be clipped off so that the protein is shorter. So the mature protein may actually lack the first methionine as well as other amino acids. So that is why you may find proteins without the hallmark methionine.
Answer from ResearchGate
Not every protein necessarily starts with methionine, however. Often this first amino acid will be removed in later processing of the protein. A tRNA charged with methionine binds to the translation start signal. The large subunit binds to the mRNA and the small subunit, and so begins elongation, the formation of the polypeptide chain. After the first charged tRNA appears in the A site, the ribosome shifts so that the tRNA is now in the P site. New charged tRNAs, corresponding the codons of the mRNA, enter the A site, and a bond is formed between the two amino acids. The first tRNA is now released, and the ribosome shifts again so that a tRNA carrying two amino acids is now in the P site. A new charged tRNA then binds to the A site. This process of elongation continues until the ribosome reaches what is called a stop codon, a triplet of nucleotides that signals the termination of translation. When the ribosome reaches a stop codon, no aminoacyl tRNA binds to the empty A site. This is the ribosome signal to break apart into its large and small subunits, releasing the new protein and the mRNA. Yet, this isn’t always the end of the story. A protein will often undergo further modification, called post-translational modification. For example, it might be cleaved by a protein-cutting enzyme, called a protease, at a specific place or have a few of its amino acids altered.
SciTable in NatureEducation also addresses what happens in translation with methionine