Where is the genetic information of the cell stored
How DNA Stores Information
here's a quick explanation about how DNA
stores information James Watson and
Francis Crick discovered the structure
of DNA in 1953 their work revealed the
remarkable way that DNA stores
information they found that DNA its full
name is deoxyribonucleic acid stores
information using a simple code the code
has four letters and involves a cool
feature called complementary base
pairing so how does complementary base
pairing work if we flatten out a DNA
helix it would resemble a ladder in DNA
each step in the ladder is made of two
pieces these pieces are called bases DNA
has four bases named adenine cytosine
guanine and thymine we abbreviate them
as a C G and T these four letters are
the DNA code a key part of Watson and
Crick's discovery was that these bases
form pairs in a very specific way a
pairs only with T and C pairs only with
G that is a and T complement one another
and C in G complement one another this
also means that C and G cannot pair with
a or T by the way an easy way to
remember which bases pair with which is
to write the letters in alphabetical
order then below that write the letters
in reverse alphabetical order so what
does all this mean for a cell when a
cell prepares to divide it replicates
its DNA so that both daughter cells have
exactly the same genetic information
complementary base pairing means cells
can replicate their DNA quickly and
efficiently during DNA replication that
double helix separates down the middle
where the pairs of faces join this
exposes the sequences of A's C's GS and
T's on each side then groups of enzymes
come along and add complementary bases
one after another along the entire
length of both DNA strands that is gene
after gene along the entire length of
the chromosome in the end there are two
identical chromosomes encoded with the
same genetic information a complementary
base pairing also plays a critical role
when cells make proteins during protein
synthesis the DNA that is the gene the
codes for the needed protein opens up
this exposes the sequence of bases in
that gene the sequence of bases is then
copied in the form of RNA but with one
important difference RNA has no T
instead of the base thymine it uses a
base called uracil so when a gene is
copied during protein synthesis every a
in the DNA is matched with a u in the
RNA you can learn more about protein
synthesis in the video how genes express
themselves scientists also use
complementary base pairing to help
understand how cancer happens for
example if they know the sequence of
bases for a piece of DNA from a cell
they can use complementary base pairing
to learn what the base sequence is for
the opposite piece gene sequencing
technology reveals the lineup of bases
in DNA and a messenger RNA scientists
can then use complementary base pairing
to identify the gene that produced
that messenger RNA once scientists know
the sequence of amino acids in a protein
they can work backwards and decipher the
sequence of bases in the messenger RNA
for the protein and then the gene that
codes for that protein it also allows
scientists to compare genes from cancer
cells and healthy cells from a patient
this helps them learn more about why
cancer happens and how tumors grow
Watson and Crick's work explained human
heredity and opened a new field of
molecular biology it also earned them a
Nobel Prize in 1962 pretty nifty
discovery huh if you'd like to learn
more about the discovery of DNA read the
book the double helix by James D Watson
shown here in an annotated and
illustrated edition
