Download Slide 1

Hon. Biology
Period 6
Nucleic Acids
Nucleic acids are
large complex
organic molecules
composed of
carbon, oxygen,
hydrogen, nitrogen,
and phosphorus
atoms. Nucleic acids
are polymers of
individual
monomers known
as nucleotides.
There are two basic kinds of nucleic acids:
ribonucleic acids (RNA) and
deoxyribonucleic acids (DNA).
RNA and DNA
both go
through
transcription.
Singlestranded vs.
doublestranded.
The Structure of DNA
DNA contains four
nitrogenous bases:
-Adenine
-Guanine
-Thymine
-Cytosine
Individual nucleotides are joined
together to form a long chain.
The Structure of DNA
In the early 1950s, Rosalind Franklin began to test
X-ray beams with DNA. The X-ray scattering produces
a pattern that provides important clues to the
structure of many molecules.
This X-ray diffraction
photograph of DNA was
taken by Franklin. The Xshaped pattern in the center
indicates that the structure
of DNA is helical.
The Structure of DNA
At the same time that Franklin was doing her work, two
English scientists were also determined to find the structure
of DNA. Francis Crick and James Watson built 3-D models
of DNA. Watson observed Franklin’s X-ray pattern of DNA
and thus realized the importance of it. Through base pairing,
they soon realized DNA’s structure was a double helix.
The structure of
the DNA double
helix resembles a
twisted ladder.
Sugar-phosphate
and nitrogenous
bases form the
ladder.
The Structure of RNA
There are 3 major differences between RNA
and DNA. The sugar in RNA is ribose, not
deoxyribose. RNA consists of a single strand
of nucleotides, and DNA is double-stranded.
The nitrogenous bases in RNA are different
than DNA.
RNA contains: Adenine
Cytosine
Guanine
Uracil
Replication
When DNA
undergoes
replication,
each of the
original strands
serves as a
template along
which a new
strand forms.
Before a cell divides, it must duplicate its DNA.
This copying process is called REPLICATION. It
is carried out by a series of enzymes. These
enzymes “unzip” the double-helix, insert the
bases, and create links to extend the chain.
Transcription
Transcription is the process by which a
molecule of DNA is copied into a complementary
strand of RNA. In other words, it is the process
of transferring information from DNA to RNA .
Translation
What's Involved in Translation?
mRNA - the template with
instructions for the order of amino
acids in the polypeptide (protein)
chain.
tRNA - molecules that transport
amino acids to site of translation
(the ribosome).
ribosomes - serves as the site of
translation and regulates the
tRNA molecule's joining with the
mRNA.