Download DNA Webquest L3

Name _______________
Journey into DNA
Date _______________
http://www.pbs.org/wgbh/nova/body/journey-into-human-dna.html
Screen 1:


The human body contains _____________________ cells.
Each cell in the body, except the _____________________ has a nucleus containing the
_________________ - a string of 3 billion ___________________________________.
Screen 3:
 Cells in the body are exact copies of ________________________, but sometimes cells need to
differentiate.
 Why is it important for cells to differentiate or specialize?
_________________________________________
__________________________________________________________________________________
_________

What role does DNA play in cell differentiation?
__________________________________________________
__________________________________________________________________________________
_________
Screen 4:
 At the heart of the control center (nucleus) is the _______________________________.
Screen 5:
 The human chromosome is made of _______ total chromosomes ( two sets of ________). Where
does
each
set
come
from?
___________________________________________________________________________
 About ______% of the human genome has no known purpose. The remaining 3% that does have a
known purpose is made of ____________ genes.
Slide 6:
 The picture on slide 6 is of one _________________________________. It is condensed so it is
visible.
The
reason
it
is
condensed
is
because
______________________________________________________________
Slide 7: Chromosome Banding
 Within each chromosome are ____________ of light and dark regions. What causes a band to be
dark?
__________________________________________________________________________________
_________
 Each leg of the chromosome has the exact same banding pattern. Look at the banding patterns on the
chromosome below. Shade in the other side of the chromosome correctly.

Each of the 23 chromosome pairs has its own unique banding pattern. How do scientists identify a
chromosome? ______________________________________________________
Slide 8: Gene
 Within each banding region are genes.
What is the purpose of genes?
________________________________
____________________________________________________________________________
 Describe
the
length
of
a
single
gene.
____________________________________________________________
Slide 9: Chromatin Loops
 How
much
DNA
is
inside
of
one
nucleus?
_______________________________________________________
 How
does
that
much
DNA
fit
into
one
tiny
nucleus?
______________________________________________
 The largest loop makes the helical form of the chromatin and causes it to look like a
___________________.
Slide 10: Chromatin Scaffold
 What
is
chromatin?
________________________________________________________________________
Slide 11: Nucleosome
 On this slide you can finally see a picture of _______.
 The
DNA
is
wrapped
around
_______________________
__________________________________
 What
keeps
the
DNA
stuck
to
the
____________________________________________________
 What
makes
up
one
____________________________________________________________
which
are
histones?
nucleosome?
Slide 12: Double Helix

Who were three scientists who worked to create the structure of DNA?
_______________________________
________________________________________________________________________________________
___
 The structure of DNA resembles a ______________________.
Slide 13: DNA Bases
 DNA is made up of four bases: ______________, _________________, ________________,
_______________
 How many bases are found on one rung of the ladder? _________
 How do these bases bond? ___________________ with _____________________
and
___________________ with _____________________
Slide 14: One Nucleotide
 The sides of the DNA ladder are made of
________________________________________________________.
 One nucleotide is made of: ___________________, _____________________, and
_____________________.
Slide 15: Molecular Structure
 How many atoms are found in one nucleotide? ________________
 Why did it take so much work to determine the structure of DNA?
___________________________________
__________________________________________________________________________________
_________
 What will be the future research on DNA?
_______________________________________________________
Answer the following questions about DNA….
(1) What do the letters DNA stand for? _____________________________________________________.
(2) DNA is in the form of a twisted ladder called a _____________________ _____________________.
(3) What four letters make up the rungs of the ladder? ________ ________ __________ ________
What do each of these letters stand for?
A = _______________________________________
_____________________________________
T=
C = _______________________________________
______________________________________
G=
(4) In DNA, the letter A always bonds with the letter __________
and the letter C always bonds with the letter _______.
(5) The sides of the ladder are made from a _________________ ________________________ backbone.
(6) Below is a strand of DNA. Complete the strand by drawing the right side of the DNA and writing in the correct base
letters. Then label the sugar-phosphate backbone.
A
If every piece of DNA in every living organism is made of only four letters (A, T, C, G) how can we all look so
different?
________________________________________________________________________________________
_
C
________________________________________________________________________________________
__________
________________________________________________________________________________________
__________
If the sperm and egg cells make a mistake when giving their sets of chromosomes to a new baby, how would
that affect the DNA of the baby?
_________________________________________________________________________
________________________________________________________________________________________
__________
________________________________________________________________________________________
__________
Our cells die off all day long and must be replaced by new identical cells. This means the DNA in the newly
made cell will be the exact same as the DNA in the old, dead cell. What might happen if the newly made DNA
has a mistake in one of its four letters?
_____________________________________________________________________
________________________________________________________________________________________
__________
________________________________________________________________________________________
__________