Download Extracting and Isolating Your Own DNA

Name (s) _____________________________________
_____
Class period
Date of lab _______________________
PRELAB. Read the lab “Introduction”, and then answer the following:
1) The length of DNA in a cell is about __________________ times as long as the cell
itself, yet it is packaged into the tiny nucleus, which takes up only about _____% of the
cells total volume.
2) To fit all of this information into the nucleus of a tiny cell, the long strands of DNA are
coiled tightly and efficiently around proteins to form compact structures called
_______________________.
3) If the entire DNA from one human cell was unraveled and lined up end-to-end it would
measure approximately _____ feet long!
4) (a) Why won’t your actual isolated DNA (in this lab) look like the double helix we see in
textbooks? (b) What will it look like, instead?
5) Why is sports drink (ex: Gatorade) used to collect the cheek cells rather than water?
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6) What exactly does the “cell lysis solution” do to the cheek cells and why is it necessary
this lab procedure?
7) The cold ethanol should make your DNA visible by separating it from the cell lysate.
What is meant by cell “lysate”?
Next Read the lab “Background”, and then answer the following:
The Code of Life
1) Why is DNA considered to be the hereditary “code of life”?
2) Define “gene”.
3) An example of a gene in humans is the melanin gene. What trait does this gene code
for?
Packaging of DNA
4) DNA forms a twisted ladder called a _______________________
_____________________.
5) In order to condense the vast length of DNA into the cell, it is wrapped tightly around
groups of _________________ proteins, like ______________ on a string. This complex
of DNA and proteins is called _________________________, and when it coils around on
itself it forms neat packages called chromosomes.
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6) Chromosomes form only during mitosis (cell division) and become visible under a
microscope. In each human body cell there are _____ (how many in total) chromosomes.
How many chromosomes (per cell) do you inherit from each parent? _______
Post-Lab Analysis:
1) Draw a picture of your test tube with DNA & label the contents. 
2) This lab will not “work” for some people - they won’t be able to collect a clump of DNA
for their necklace. Explain how it is possible to have actually successfully extracted DNA
from your cheek cells, yet at the end of the lab procedures, it is not obviously visible.
3) What are some things that a scientist could do with extracted DNA from a human? (list
several ideas) What about from any other organism?
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4) Draw a sketch of a typical cheek cell here. Label the cell membrane, nucleus,
cytoplasm, and chromosomes.
5) Does a liver cell contain the same chromosomes as a cheek cell? Explain why (or why
not).
6) Imagine you are trying to explain the difference between chromosomes, genes, and
DNA to your younger brother or sister. Write down your explanation in simple words that
they could understand (or make a simple analogy).
7) Insulin is a hormone produced by some specialized cells in the human pancreas. If
you wanted to isolate a copy of the gene that codes for insulin, could you also find that
gene in a cheek cell? Explain.
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