UNIT
3 Molecular Genetics
The chicks of this white-crowned sparrow will
learn the song of their species only if they hear it
at least a few times within the first month of their
lives. They will not learn the song of any other bird,
however, no matter how often they hear it.
What genetic mechanisms are at work here?
Clearly there is a song-learning skill programmed
into the cells of the chicks. There is also an element
of timing, since this skill is only activated during a
specific stage of the chicks’ lives. Finally, there is
an environmental component, since the chicks’
innate ability to learn the song can be fulfilled
only if they hear the correct song.
All these components can be traced to the
expression of stored hereditary information through
proteins created by specialized cellular structures
like the ones shown below. The genetic information
inherited by each chick defines which proteins will
be created in each of its cells throughout its life. In
turn, these proteins set the stage for the chick’s
development. But how can the information leading
to a behaviour like singing be stored in and
transmitted by molecules? How do these processes
interact with each other, and with the outside world?
The task of molecular genetics is to examine how
genetic information stored on molecules is expressed
in the world — whether that expression takes the
form of an illness, a new strain of rice, or the song
of a bird. In this unit, you will also consider some of
the practical, legal, and ethical issues that arise from
our increasing understanding of the processes of life.Unit
Contents
Chapter 7
Nucleic Acids:
The Molecular
Basis of Life......
Chapter 8
Protein Synthesis and
Gene Expression...
Chapter 9
DNA Mutations and
Genetic EngineeringUnit Project......^322284250216214
Unit
Preview
In this Unit, you will
discover
how living cells store,
transmit, and express
genetic information,
how the outside
environment affects the
nature and expression of
genetic material within
cells, and
how new genetic
technologies are
transforming science
and society.Specialized structures use the information encoded
in hereditary material to construct proteins.Read pages 322–323
before beginning this unit.
Throughout the unit, think
about the roles played by
DNA and its associated
proteins in the development
and treatment of cancer.
Start planning for your
project now by setting up
a system to organize the
information you gather.UNIT PROJECT PREP