Hello, my name is Dr. Carole Sargent, and I
work in the Department of Pathology at the University of Cambridge.
My background is in Genomics and Genetics.
Today we're going to look at the Central Dogma of Molecular Biology.
We're going to cover this in two lectures.
This is the first,
which looks at gene structure, expression,
and regulation within the context of DNA structure and replication. The central dogma of
molecular biology states that there is
a sequential flow of information that ends with the generation of protein.
Information cannot flow between proteins of actual protein to a nucleic acid.
This is generally interpreted as illustrated in the diagram.
Deoxyribonucleic acid or DNA,
is the heritable state which encodes the information for
the generation of ribonucleic acid molecules through the process of transcription.
RNA and specifically messenger RNA is
the transient intermediate that undergoes translation to generate the protein molecules.
In reality, the control of protein expression is more complex than this simple diagram,
often including regulation of DNA and RNA
by multiple proteins and other types of RNA molecules.
The identification of DNA as
the heritable nucleic acid was first determined through experiments with bacteria.
Streptococcus pneumoniae has two morphologically different forms.
When cultured on microbiological plates,
the highly pathogenic strains developed colonies with a smooth and glossy appearance.
The non-pathogenic colonies have a rough appearance.
Avery, MacLeod, and McCarthy showed that mixing
live non-pathogenic bacteria with dead cells or
cell extracts from the pathogenic strains converted
the phenotype from rough to smooth with a concomitant change in pathogenicity.
They subsequently extracted the different components
from the pathogenic strains and were able to
deduce that it was the DNA that had
this capacity to transform the rough colonies to the smooth.