Please wait while the transcript is being prepared...
0:00
Hello. My name is Jim Haber.
I'm a professor of biology at
Brandeis University in Waltham,
Massachusetts,
outside of Boston.
I study how DNA is repaired.
I have been doing
so for a long time.
In fact, when I went
to college in 1961,
it was the same year
that messenger RNA
was hypothesized and
then demonstrated,
the same year that
the lactose repressor
was postulated, and
the same year that
the triplet genetic
code was deciphered.
So, I've had an
opportunity to follow
this field for a long time.
0:36
I'm going to talk about how
our DNA is repaired
and preserved.
To begin with, I will say
something about the
structure of DNA and
remind you about the
structure of genes
and the organization
of the genetic code,
and then talk about a number of
different ways in which
damage occurs to DNA,
and which our cells have
the capacity to repair.
1:00
There are, in fact, many
different assaults on DNA,
changes that happen during
the copying of DNA,
changes that happen because
our DNA is exposed
to oxidative damage,
damage that occurs by accidental
breaks in the DNA sequence,
and even more serious
breaks that rupture
both strands of DNA
so that the DNA is
no longer connected,
for example, to its centromere.
I'll talk a little bit about
each of these, although most of
the discussion of
double-strand break repair
will actually be in
another lecture.
1:39
Just to remind you,
DNA is a double helix, as
you undoubtedly remember.
It is made up of base pairs
between two purines
and two pyrimidines:
cytosine, thymine,
adenine, and guanine.
These bases are arranged
such that As pair with Ts,
Gs pair with Cs, and that
this pairing between
these bases then leads to the
structure of a double helix,
in which the two strands are
in an antiparallel arrangement
and the pairing between
these bases assures
that they can be
properly replicated.
