Central dogma of molecular biology | Chemical processes | MCAT | Khan Academy

Central dogma of molecular biology | Chemical processes | MCAT | Khan Academy


– So what exactly is the central
dogma of molecular biology? Well, really it could just be called the central dogma of all
of life because it explains how you and I take this conglomeration of genetic information
from each of our parents, and how this information
gets transferred into generating a full-blown
human being, like you and me. So some very clever scientists, Francis Crick and James Watson, or “Watson and Crick,” as
they’re often referred to as, are credited with discovering this dogma, which they say deals with the detailed residue-by-residue transfer
of sequential information. Or, as Marshall Nirenberg,
who won the Nobel Prize in Physiology and Medicine, once said, “DNA makes RNA makes protein.” And I think this simple explanation
really just says it all. So let’s explore this
concept a little bit further. So we have three major players here. DNA and RNA are nucleic acids, which are made up of nucleotides, and proteins are made up of amino acids. And the information starts
at the most basic level stored as DNA, which can
then be re-stored as DNA when DNA copies itself in a
process called “replication.” Then DNA can be copied into RNA in a process called “transcription.” And then finally you can
use the information in RNA to synthesize a protein in a
process called “translation.” Now since DNA, RNA, and
protein are linear polymers, this means that each
individual unit, or monomer, is only attached to, at
most, two other units. So say we have a monomer,
which is just one unit. They are connected in a series like this, which makes it a linear
polymer, and this is the same for DNA if each of these
is a deoxyribonucleic acid, for RNA if it’s a ribonucleic acid, or a protein, which are just amino acids all connected in a linear polymer. So what does this mean? This means that the specific sequence of each of these monomers
effectively encodes information, and that that transfer of
information is faithfully preserved from DNA to RNA to protein. Each polymer sequence
is used as a template for the synthesis of the next polymer. And you could go into any
step in this sequence and determine what the corresponding
polymers would look like. So in other words, you
could take DNA and obviously figure out what the corresponding
RNA would look like, and then what the corresponding
protein would look like. So this whole process
is the central dogma. It can sometimes be a
little bit tricky to keep all of these terms straight,
so I’ll try to break it down a little bit for how I
like to remember them. For DNA, I think it’s pretty easy. When you go from DNA, and DNA makes a copy of itself, it’s called replication because DNA is just replicating itself. It’s making the same copy of itself. Transcription and translation,
on the other hand, it’s kind of easy to get
these two terms mixed up. One of them obviously is
talking about DNA to RNA, whereas the other one is talking about going from RNA to protein. So if you look at the word
transcription, it has the word “script” in it, so I think
of it as going from one written form to another
kind of written form, and both use nucleic
acid, so they both use this sort of alphabet, if
you will, of nucleic acids. And so you’re just going
from one kind of alphabet to the next kind of alphabet. Translation, on the other hand,
which is also the same term that we use when translating
one language to another, describes going from
nucleic acid to amino acid, so it’s like you’re using
one kind of language and going to another kind of language, because you’re going from
nucleic acid building blocks to amino acid building blocks. So hopefully that helps you keep these terms straight a little bit. So what did we learn
about the central dogma? Just remember the simple statement that DNA makes RNA, which makes protein.

22 thoughts on “Central dogma of molecular biology | Chemical processes | MCAT | Khan Academy

  1. The neatest handwriting I have come across. 🙂 And I sat through the entire 4 minutes 21 seconds just because of the hand writing and the voice. 🙂

  2. @2:35 I was under the impression from prior learnings that we don't have a reliable system yet for predicting tertiary protein structure based simply on the DNA, RNA, or primary amino acid sequence.

  3. So I really don't know – I'm reviewing this as part of an exam – but Wikipedia also lists three special cases of transfer as part of the Central Dogma which only happen under certain conditions. RNA can reverse-transcript DNA in some retrovirus cases, RNA can transcript itself in some cases (viruses,) and under lab conditions DNA can directly translate to proteins. The other paths (Protein->RNA, Protein->DNA, Protein->Protein) are unknown to exist. Is that also part of Central Dogma, even if it is usually not part of a Freshman Biology class?

  4. simple. Translation comes after transcription in the dictionary. Thats how i remember it.

    BTW: they are all in alphabetical order 😛

  5. Very good Video but RNA to DNA by the process of Reverse Transcription should be included(LIKE if understand)

  6. I like your video but I do not know much English. I am in basic 7 just. Please put subtitles in Spanish

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