#officialfam

[snails-official]

does anybody remember me 😞

[biochemistry-official]

The Central Dogma

What is it? The central dogma is a common way to refer to one of the most fundamental concepts in biology: how organisms store, transmit, and act upon information. It was coined by Francis Crick partially because he forgot the meaning of the word 'dogma.' (Really, he did).  Basically it goes like this:

Image Credit: Khan Academy, “Intro to gene expression”

Long term storage of information (like how to build a protein, or how often a cell should divide) is stored in DNA. When the cell needs that information, the DNA is transcribed into messenger RNA, or mRNA. Then, that mRNA is translated into a chain of amino acids, which folds into a protein that can do work within the cell. It could perform a chemical reaction, become part of a cellular structure, regulate transcription of specific genes, etc.

The DNA to RNA transition is called transcription because the mRNA is basically a copy of the DNA but with a slightly different molecule. It's pretty easy to look at an RNA sequence and figure out what portion of the DNA it was transcribed from. The RNA to protein transition is called translation because it's like the RNA is being translated into a completely different language. Every three bases of RNA (a codon) codes for a specific amino acid. But, since there are 64 possible combinations of RNA bases and only 20 amino acids, there is a lot of redundancy. If you know the exact sequence of amino acids in a protein, you can't figure out the exact RNA sequence that created it.

What are the exceptions to it? Although broad, simple theories are appealing, they almost never capture the true complexity of life. The central dogma is true for most processes in the cell. Genes make RNA, which makes protein. However, there are some exceptions.

Viruses lack the ability to replicate or reproduce by themselves, so they have to infect other cells to survive. Some viruses don't have a genome made of DNA, they have an RNA genome instead. One class of these is called retroviruses, because they move backwards against the usual flow of information described by the central dogma. When they invade the cell, they reverse transcribe their RNA genome into DNA, which gets inserted into the genome of the host. HIV (human immunodeficiency virus) is an example of a retrovirus.

Prions are another example of a process that defies the central dogma. They are proteins that can cause disease by triggering other proteins to switch into a misfolded state. They are infectious, but they don't have any RNA or DNA genomes, they're just a single protein. The first prion discovered was called Prion Protein, because scientists are very creative. Many animals have genes for prion proteins and have tons of normal, healthy prion protein in their bodies. However, these proteins can change shape (misfold) into an alternate, infectious state. Once one protein misfolds, it gets all the other prion protein around it to misfold as well. They clump up into giant, stable aggregates of proteins, which end up killing the cell they're in. Then, the prions find other cells to infect and kill. So, they act like pathogens, but they don't have any genome and don't even fit the definition of a living thing. Examples of prion diseases include mad cow disease, Creutzfeldt-Jakob disease, kuru, and possibly Alzheimer's (the research on this is still pretty new). There are no current treatments for prion diseases, but fortunately they are pretty rare.

[cicadis-blog]

On hiatus until further notice

I simply don't have the time (or inclination) to continue this blog anymore. It was a fun two (3?) years, and almost 3200 people came along for the ride.

Best wishes to you all, keep learning! :)

[usaac-official]

On This Day

April 18, 1942:  Doolittle Raid on Japan.  In one of the most innovative and audacious raids of the war, sixteen B-25B medium bombers under the command of Lt. Colonel Doolittle launched from the carrier Hornet to strike the Japanese Home Islands.  Although the task force was detected early and launched the bombers 200 miles further out than planned, all sixteen managed to make the Asian mainland after bombing their targets.  Of the eighty crew, three were killed during the crash-landing of their aircraft, while four more eventually died in captivity.  Fifteen of the Mitchell bombers were destroyed, with the final one being interned by the Soviet Union in Vladivostok.  The raid did almost no material damage, but was nonetheless a huge morale boost for the American public.

[badpuns-official]

[library-official]

HAPPY BIRTHDAY NASA! On July 29th 1958 NASA was created. Wow @nasa-official we should have gotten you a present ;) Instead here’s a present for everyone! Did you know that Nasa has a ton of ebooks for free? Browse the list and tell me your favourites!

[chemistry-official]

Day 99 - Einsteinium

In the seventh Period and the thirteenth Group, Einsteinium was named after the famed physicist Albert Einstein. Einsteinium was first discovered when the remains of the the first Hydrogen bomb. The discovery of Einsteinium wasn't publicized until 1955 because of heating tensions between the USA and the USSR. There's no current uses for Einsteinium other than research. Einsteinium glows blue in the dark because of the radioactive breakdown of the element.

[astrophysics-official]

Interesting video about what all of math covers! Worth a watch.