Biology (Holt)

5.Begin a model of a human chromosome
fragment made by a restriction enzyme.
Place nucleotides for one DNA strand in
the following order: BBRRYGGBRY. Build
the second DNA strand by arranging the
remaining nucleotides in the following
order: BRRYGBYYGG.

6.Match the complementary portions of the
two strands of DNA you made in step 5.
Pair as many base pairs in a row as you
can. Make a sketch showing the sequence
of bases in your model of a human chro-
mosome fragment.

7.Imagine that the restriction enzyme that
cut the human chromosome fragment you
made in steps 5 and 6 is moving around
your model plasmid until it finds the
sequence YRRBBG and its complementary
sequence, BGGYYR. This restriction
enzyme cuts each sequence between a B
and a G. Find such a section in your sketch
of your model plasmid’s DNA.

8.Simulate the action of the restriction
enzyme on the section you identified in
step 7. Open both strands of your model
plasmid’s DNA by pulling apart the adja-
cent green and blue nucleotides in each
strand. Make a sketch of the split plasmid
DNA molecule.

9.Move your model human DNA fragment
into the break in your model plasmid’s DNA
molecule. Imagine that a ligase joins the
ends of the human and plasmid DNA. Make
a sketch of your final model DNA molecule.

PARTB: Cleanup and Disposal

10. Dispose of damaged pushpins in the
    designated waste container.


11. Clean up your work area and all lab
    equipment. Return lab equipment to
    its proper place. Wash your hands thor-
    oughly before you leave the lab and after
    you finish all work.

Analyze and Conclude

1. Comparing Structures Compare your
   models of plasmid DNA and human DNA.


2. Relating Concepts What do the
   sections of four unpaired nucleotides
   in your model human DNA fragment
   represent?


3. Comparing Structures How did your
   original model plasmid DNA molecule dif-
   fer from your final model DNA molecule?


4. Drawing Conclusions What does the
   molecule you made in step 9 represent?


5. Further Inquiry Write a new question
   that could be explored with another
   investigation.

CHAPTER 11Gene Technology 247

G

G

Y

Y

Y

Y Y

G

R

R

R

R

R

R

R

B

B

B B

B B

G

G

G

G

G

G

G

B

B

R

R R

Y

Y

Y

On the Job

Genetic engineeringis used to produce

many products that are useful to

humans. Do research to discover how

genetic engineering is used to better

our lives. For more about careers, visit

go.hrw.comand type in the keyword

HX4 Careers.