Lesson 1.3 Identity: Molecules and Cells - Overview


Nov 30, 2013 (3 years and 10 months ago)


Lesson 1.3 Identity: Molecules and Cells



In lesson 1.3, students will examine the role molecules, such as DNA and protein, and cells play in identity.
Cells in the body contain chromosomes; the DNA that makes up these structures
controls the body’s production
of proteins and ultimately, human structure and function. Our genes code for the proteins that contribute to
physical features such as skin pigmentation and eye color. Specific genes have been shown to put a person at
ed risk for disease while others have been linked to personality. DNA provides a unique code of over
three billion base pairs. Unless you are an identical twin, there is no other person on the planet with your same
code. And although only one tenth of one
percent of this DNA differs from person to person, the regions


vary provide a true genetic blueprint of an individual.

In this lesson, students will return to their study of the skeletal remains. Using simulated DNA samples
collected from the bones

of the skeleton, students will now use molecular techniques to determine identity.
Students have explored the tools of molecular biology in PBS, but they have yet to explore restriction enzymes
as a tool for cutting DNA. In this lesson, students will run
restriction analysis on simulated DNA samples from
the skeleton and from missing persons who match the physical description provided by the bone analysis. Since
each person has a unique genetic code, these enzymes will make a different number of cuts in th
e DNA, leaving
a varying number of fragments. These restriction fragments will be separated via gel electrophoresis and the
resulting restriction fragment length polymorphisms (RFLPs) will be compared. Students will add to their case
report from Lesson 2 a
nd make a final conclusion regarding the identity of the skeleton. Students will also
investigate the various career areas they have worked through in the unit.

To wrap up the unit, students will explore the technology being used to secure and verify ident
ity. Biometrics is
the field of science dedicated to using physical characteristics, such as facial features or patterns in the eyes, and
behavioral characteristics, such as voice or handwriting, to determine or confirm identity. Students have most
seen this technology in movies or on TV, but few may realize that biometrics is not just science fiction.
Biometrics is becoming more widely used to identify individuals and to authenticate that they are who they say
they are. Simple biometric scanners hav
e been prototyped in airports and have even been added to some theme
parks to link a person to his or her admission ticket.



Human DNA is a unique code of over three billion base pairs that provides a genetic blueprint of an


riction enzymes recognize and cut specific sequences in DNA.


Gel electrophoresis separates DNA fragments based on size and is used in Restriction Fragment Length
Polymorphism (RFLP) analysis.


Physical characteristics can be used to confirm or authenticate

Knowledge and Skills

It is expected that students will:

Explain how restriction enzymes cut DNA.

Describe how gel electrophoresis separates DNA fragments.

Recognize that gel electrophoresis can be used to examine DNA differences between individua

Outline current biometrics technology.

Digest DNA samples using restriction enzymes.

Demonstrate the steps of gel electrophoresis and analyze the resulting restriction fragment length
polymorphisms (RFLPs).

Essential Questions


What is the structure
and function of DNA?


How does DNA differ from person to person?


What role does DNA play in our identity?


How can tools of molecular biology be used to compare the DNA of two individuals?


What are restriction enzymes?


What are restriction fragment length po


What is gel electrophoresis and how can the results of this technique be interpreted?


How can the field of biometrics be used to verify and protect identity?