Download Replication is when DNA

Name ________________________________________________ Block - ____ Date ___________________
DNA Webquest
I: DNA – Structure and Function
1.
Log onto the computer and click on the internet icon. Enter the following web site address exactly as shown:
http://www.pbs.org/wgbh/nova/genome/dna.html#
2.
Select Journey into DNA (choose the first one listed – which requires Flash).
3.
Once the page has loaded, maximize the page (choose the large box next to the red box with the X in the upper right-hand corner).
4.
Read the information to the right of the picture. Once you have finished reading, click on the magnifying glass with the + sign in
the middle. This will take you to the next screen where you will read more information. For each slide there will be several
questions that you will need to answer below (the order of the questions corresponds to the information on the slides).

About how many cells are in the human body? __________________________________________________________

A string of three billion A's, C's, G's, and T's make up the __________________________________ that is found in every
cell in the human body, except for _____________________________________.

Different kinds of cells in a person’s body have (circle one) the same / a different DNA code.

These cells and others in the body are exact copies of their parent cells -- they formed when their parent cells divided. But
sometimes cells need to ________________________________, or become ________________________________.

o
Within the first month of embryonic development, cells are changing into different forms. If they didn't, all of the
body's cells would be exactly like the single __________________ cell from which they all originated.
o
This production of new types of cells is the result of DNA "turning on" and "turning off" different sections of the
information it stores.
Within every cell (except red blood cells) is a ________________________________ -- a sphere-like structure separated
from the rest of the cell by a membrane.
o


The human genome is comprised of two sets of ________________________________ -- ______ chromosomes in all.
o
Each parent contributes a set. About 97 percent of the genome consists of sequences that don't code for proteins and
have no known function.
o
Within the rest of the genome are an estimated ______________________________ genes.
The single chromosome displayed here and those on the previous screen are shown in their most compacted state -- they're
about to ______________________________, along with the cell, through the process of ________________________.
o



The nucleus acts as the cell's ________________________________, regulating its growth, metabolism, and
reproduction. At the heart of this control center is the human genome.
When we see pictures of chromosomes, this is usually what we see. The reason is that chromosomes are most visible
during this time.
When stained, chromosomes show ________________________of light and dark areas.
o
The dark bands indicate areas where the structure of the chromosome is dense.
o
Each of the 23 chromosome types has a ________________________ banding pattern. (A chromosome pair has
identical banding.)
o
In fact, scientists can identify a chromosome based solely on its banding pattern.
________________________ determine whether you have brown eyes or blue, long toes or short, and much, much more.
o
Genes also control everything from how your cells grow to how they interact with one another.
o
A single gene can range in length from as few as 100 DNA bases to as many as several million.
There's a lot of DNA within the ________________________-- about __________________feet if you could unravel it and
stretch it out end to end.
o
To fit such a long molecule within the tiny space of the nucleus, DNA bends and loops in several ways.
o
The largest of these loops results from the helical coiling of ______ ______ ______ ______ ______ (the thick line
in this illustration). This coiling causes the chromosome to resemble a spring.
Page-1M. Stockdale (WHS)



We've now zoomed in enough to see portions of the DNA strand. The DNA is wrapped around histones -- ______structures
that are sometimes depicted as discs.
o
Histones carry a slight positive charge, and DNA carries a slight negative charge.
o
Since opposite charges _____________________, the DNA is pulled in toward the histones.
Here is a view of the double ________________________ -- the subject of Rosalind Franklin's Photo 51.
o
With the help of her photograph, James ____________________ and Francis _______________________ were able
to piece together the first accurate model of DNA.
o
Note how the structure of DNA resembles a ____________________ __________________________.
The DNA molecule is made up of four bases -- ____________________ (A), ____________________ (C),
____________________ (G), and ____________________ (T). Each rung of the DNA ladder consists of two bases.
o

In the DNA molecule, A always pairs up with _______, and C always pairs up with _______.
The sides of the DNA ladder consist of a long string of sugar and ______________________________ molecules, to which
the bases are attached.
o
Each (3 parts) sugar-phosphate-base combination is called a ______________________________.
II: Find out what DNA can do…
1.
Enter the following web site address exactly as shown:
http://www.pbs.org/wgbh/aso/tryit/dna/index.html#
2.
3.
Find where it says Go directly to DNA Workshop Activity. Click on the underlined DNA Workshop Activity
Maximize this new page (make it full size).
A. DNA Replication
4.
5.
6.
Copy down the description of the process called replication (found below the box with the word replication in it).
Replication is when DNA, ________________________________________________________________________
______________________________________________________________________________________________
Click the words DNA REPLICATION.
In the space below, copy down the original sequence of bases found in both strands of DNA.
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
C
G
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
Parts of the DNA Backbone:
D = __________________________
P = __________________________
The steps of DNA Replication:


BELOW THE BOX THAT SAYS DNA REPLICATION, YOU WILL FIND THE DIRECTIONS TO HELP YOU GO THROUGH THE STEPS OF
REPLICATION.
BE SURE TO ANSWER THE QUESTIONS FOUND BELOW.
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Step 1: UNZIP DNA
A. What type of molecule causes the above to occur? (Hint: it’s name is Helicase) ______________________________
B. Where in the cell is replication occurring (Hint: look at the diagram that says you are here)? _______________
SO WHAT HAPPENED? In the light blue box that appears to the right you will find an explanation of WHAT
HAPPENED. Read and then answer the following questions:
1. Molecules (of genetic material) unwind from spool made of _________________________________________.
2. The DNA resembles a ladder after what happens to the molecule? _____________________________________
3. Special kinds of proteins called _______________________________ are used to break the rungs of the ladder.
4. What is left looks like _______________________________________________________________________
Click OK
Step 2: Match bases to make two new DNA strands.

An enzyme, DNA Polymerase, is responsible for carrying out the second step of DNA Replication.
A. In order to complete the above step, you need to follow the base-pairing rule.
B. Fill in the base-pairing rule as it applies to making complementary strands of DNA:
Bases found in DNA
Complementary bases in DNA
G
C
T
A
SO WHAT HAPPENED? In the light blue box that appears to the right, you will find an explanation of What Happened. Read
the paragraph below where it says “Replication is complete” and fill in the following information:
** The new DNA molecules consist of only a few _______ ______________. This is not so with real __________. Each
____________ chromosome, for example, contains _______________ of base pairs. All _________ human chromosomes
contain ___ ____________ pairs.
Click on OK once you have finished copying down the above information.
 Click the START OVER button.
 Go through REPLICATION one more time, without interruption.
 When finished, click the START OVER button again (but this time you will not select the REPLICATION button.
B: Protein Synthesis

Click on the Protein Synthesis box to begin the next section. BE SURE TO ANSWER THE QUESTIONS FOUND
BELOW.
The steps of Protein Synthesis:

Unzip the DNA and Read the What Happened box.
1. What type of molecule breaks the rungs of DNA causing it to unzip? (it is called Helicase) ________________
2. Where in the cell is this first part of protein synthesis occurring? __________________________________

Then click OK
Part 1 of Protein Synthesis: TRANSCRIPTION:
Step 1: Match DNA and RNA bases to make a new RNA strand (After you have unzipped the DNA)
 An enzyme, RNA Polymerase, is responsible for carrying out this part of protein synthesis.
A. In order to complete the above step, you need to follow the base-pairing rule.
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M. Stockdale (WHS)
B. Fill in the base-pairing rule as it applies to making RNA from DNA:
Bases found in DNA
Complementary bases in RNA
G
C
T
A
C. Follow the directions by matching up the appropriate RNA bases with the single strand of DNA (click & drag).
D. When finished matching the bases on the computer screen, copy down the letters in the strand of DNA and its
complementary strand of RNA as it appears on the screen.
mRNA
R
P
R
P
R
P
R
P
R
P
R
P
R
P
R
P
R
P
R
P
R
P
R
DNA
C
A
G
T
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
P
D
Parts of the DNA Backbone:
D = __________________________
P = __________________________
Parts of the RNA Backbone:
R = __________________________
P = __________________________
E. SO WHAT HAPPENED IN TRANSCRIPTION In the light blue box that appears to the left you will find an
explanation of WHAT HAPPENED. Read both of the paragraphs below and fill in/answer the following:
The ______ molecule you’ve just ________________ consists of _____ bases. In a real cell, the RNA molecule
would be anywhere from _____ to __________ bases long.
1. What is an RNA molecule transcribed from DNA called? What is a shorter name?
_________________________________________________________________________________________________
2. What happens to the above molecule after transcription?
_________________________________________________________________________________________________
_________________________________________________________________________________________________
3. What happens outside of the nucleus?
_______________________________________________________________________________________________
F. Click OK. Be sure to watch the picture of the cell to see where you are moving to in the cell.
Part 2 of Protein Synthesis: TRANSLATION:
BEFORE you start matching up the mRNA codons with the tRNA anticodons, complete the following questions!!!
A. Where in the cell is the above process occurring? _______________________________________________________
B. Using only the information in the picture, what do you think a codon is? ___________________________________
____________________________________________________________________________________________________
C. Using only the information in the picture, what do you think an anticodon is? ______________________________
____________________________________________________________________________________________________
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D. Glycine, Serine, Valine, Methionie and Arginine(which are attached to tRNA molecules on the screen) are
examples of ____________________ _________________________.
E. Find a tRNA anticodon that will match up with the first mRNA codon (click & drag it).
F. Use the information found in the What Happened box to answer the following questions.
1. What is the purpose of the mRNA attaching to a ribosome? ___________________________________________
_____________________________________________________________________________________________
2. What is a codon? How many bases make up a codon?
_____________________________________________________________________________________________
3. What is an anticodon? How many bases make up an anticodon?
_____________________________________________________________________________________________
4. How do amino acids relate to all of this?
_____________________________________________________________________________________________
F. Click OK.
I. SO WHAT HAPPENED IN THE SECOND STEP OF TRANSLATION? Match up the second codon with the proper
anticodon? (Read the information found in the What Happened box and answer the following questions).
1. What did the ribosome do?___________________________________________________________________
2. What did the second tRNA bring with it? Describe this amino acid’s role .
______________________________________________________________________________
3. After the ribosome moves to the right, what happens to the first tRNA?
_____________________________________________________________________________________________
Click OK
J.
SO WHAT HAPPENED IN THE LAST STEP OF TRANLATION? What happened after you matched up the
third codon with the proper anticodon? (Use the information found in the What Happened box to answer to the
following questions).
1. What is also referred to as the “protein under construction”? How long is it?
_____________________________________________________________________________________________
2. How long do these chains typically become?
_____________________________________________________________________________________________
3. How does protein synthesis end? What happens with the ribosome?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
K. Click OK

Click the Start Over button. Go through protein synthesis one more time, without interruption.
Wrapping it up… what have you learned?
Using what you saw on the computer today, complete the following questions. If you are still uncertain, you may refer to
the following websites for additional help.
Fill in the blank(s) in each statement on the next page. However, if you are uncertain about some answers, go to the
following website for more support: http://www.lewport.wnyric.org/jwanamaker/animations.htm (scroll down and select
the button ‘Protein Synthesis’).
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Protein synthesis is the making of proteins using the information (or instructions) found in a molecule of _____________.
Proteins are long chains made out of small molecules called ____________________
_______________________.
Steps of Protein Synthesis:
1. A gene made up of DNA will ______________, just like the DNA does during replication.
2. Using one of the strands of DNA, a single-strand of _________ forms and transcribes the genetic information from the DNA.
3. The DNA zips closed and the mRNA leaves the nucleus and travels to the ___________________to build a protein molecule.
a.
The information in the mRNA which amino acids should be in the protein chain.
b.
A molecule of tRNA will carry in the proper amino acid, one at a time.
4. The two amino acids are linked together by a ___________________ bond.
5. The next tRNA will carry in the proper amino acid, and the process will continue as the amino acids are linked into a chain.
6. The chain of amino acids is called a __________________ and when it is very long it is called a _____________.
7. Most proteins are _________________________ to _________________________ of amino acids long.
8. The shape that the chain folds into is important because a protein’s shape determines it _____________________.
Answer the following questions by using the information that you have learned doing this lab (and what’s in your notes).
A. What are the two major steps involved in Protein Synthesis (list them in the correct order)
Protein Synthesis = ______________________________ + ___________________________________________
B. What is the purpose of a cell going through replication (why does it need to do this)?
C. What is the purpose of a cell going through transcription and translation (why does it need to do this)?
D. Where in the cell do the following processes occur (i.e., cytoplasm, at the ribosome, nucleus, etc.)?

Replication – _______________________________________________________________________

Transcription – _____________________________________________________________________

Translation – _______________________________________________________________________
E. Place a check in boxes below to indicate which nucleic acids are involved in Replication, Transcription and Translation.
Name of the Process
DNA
mRNA
rRNA
tRNA
Replication
Transcription
Translation
Go to the following website for more support: http://www.dnai.org/a/index.html
1.
Select the button at the bottom that says ‘READING THE CODE’
2.
When the next screen appears select he button at the top ‘putting it together’
3.
Select the button in the lower left corner ‘Translation See how the DNA code is read to make protein’
4.
If time permits go back when done with the above module and try the Interactive module found below the Translation
button described in step 3 (Be the ribosome).
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