The Physics of DNA
the basics
- the physics
- an intro to
replication - the physics of
replication - bibliography
THE BASICS OF DNA
All genetic information that
is passed down from parents to children is contained in DNA.
The information found in DNA is organized into long
stretches of DNA called genes.
DNA's structure: DNA is
made up of nitrogenous bases, often just called bases, and a
phosphate-sugar backbone.
There are four bases,
each with a unique structure: adenine, guanine, cytosine and
thymine.
As you can see,
adenine and guanine both have a double ring structure, and are
called purines. Thymine and cytosine
only have one ring,
and are called pyrimidines. In DNA, there is a base on each
side of the double helix, because
it is formed by two strands. The bases on the two strands are
complementary, which means they always pair with one
another. Thymine always pairs with adenine, and cytosine
always pairs with guanine. Together with a phosphate group and
a deoxyribose sugar, a base forms the nucleotide unit, which
is what DNA is made out of.
When there are many of these assembled together, a
strand of DNA is formed. These strands are connected
by hydrogen bonds formed between the complementary bases.
This may not sound like the key of all genetic knowledge,
but the order that these bases occur in the strand
of DNA are turned into RNA. RNA is like DNA, but instead of
having thymine, RNA has a similar base called
uracil. DNA is 'unzipped' so to speak, and an RNA strand is
created by assembling nucleotides that are complementary to
the DNA on a new RNA strand in a process called transcription.
Once the RNA strand has been created, it travels out of the
nucleus
and into a ribosome. Every three bases of RNA encodes a certain
amino acid. When the RNA goes into a ribosome,
the ribosome reads three bases at a time. The amino acid that
those three bases encode is attached to the ribosome. A
chain of these amino acids is made, and these amino acids build
a protein. This process is called translation.
So really your DNA just makes proteins, although the process is
quite complicated.
