What Is This Stuff???
• Get a stamp on R&C q’s
• Entry Task: What is Papain?
“What is This Stuff?”
R & C q’s
1. What do you think was the purpose of each procedural step? Add
this to the “why” column of your procedure chart.
2. If we had used cow liver, peas or mushrooms, how would our
results have compared?
3. This protocol (procedure) isolated DNA, not protein. How do you
know that?
4. Did the isolated DNA look like you expected? What did you expect
it to look like?
5. How might you prove that DNA is present in all living cells and not
present in non living things?
6. How might you modify this protocol (procedure) to get better
results?
7. What is papain?
Clips of DNA
KEY CONTENT: DNA Structure
LEARNING TARGET: I can use models to learn
about DNA’s structure
Clips of DNA
Part I: DNA’s Structure
“What is the structure of DNA?”
• Make a box about ½ a page in size under the
Investigative Question.
• Read “The Code in DNA” (page 406) together;
write key terms, make sketches, etc. about
DNA’s structure in your note box.
Clips of DNA
Part I: DNA’s Structure
“What is the structure of DNA?”
• Use the colored paper clips to build a model
of DNA.
– Your model should be 15 nucleotides long and
must contain all 4 nucleotides.
Clips of DNA
Part I: DNA’s Structure
“What is the structure of DNA?”
• Record the sequence of your DNA model in
your lab notebook.
– Write your sequence horizontally
– For ease, just record the first letter of each
nucleotide (ex: Adenine = A)
• Have your neighbor check your work.
Clips of DNA
Part I: DNA’s Structure
• Read “Double The Code” together; write key
terms and ideas in your note box.
• Shorten your DNA model to 8 nucleotides.
Be sure it contains at least one of each
nucleotide.
• Record this new sequence vertically in your
lab notebook
Clips of DNA
Part I: DNA’s Structure
• Build a new DNA strand next to your 8
nucleotide strand.
– Make sure your new strand COMPLEMENTS your 8
nucleotide strand!
– Record this complementary strand next to the
original strand.
• Now make a careful sketch of your double
stranded DNA model. Label the nucleotides
and show the helical structure of DNA (refer to
figure 8.11 for help!)
Clips of DNA
Check for Understanding!
• Read “Copying DNA” together. (page 413)
• Make a new note box. Record notes as we
read.
– “Unzip” your 6 nucleotide model of DNA.
– Replicate your DNA by complementing the bases.
– Have your neighbor check your work.
Clips of DNA
R & C q’s!
1. What is DNA polymerase?
2. When does DNA replication occur?
3. Why must DNA replication be accurate?
Clips of DNA
During replication in human cells, DNA
polymerase adds nucleotides at a rate of 50
per second
Initially, the error rate in newly replicated
DNA is about 1 error in 10,000 base pairings
After proofreading by DNA polymerase, the
error rate is approximately 1 error in
1,000,000,000 base pairings