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