Agenda Wednesday 11/04/15
1)Warm-Up (5 minutes)
2)DNA Replication Videos (10-15 minutes)
3)DNA Replication Chunking (18 minutes)
4)Individual DNA Replication Summary
Paragraph (5 minutes)
5)Group Poster Peer Evaluation (2 minutes)
Warm-Up Wednesday 11/04/15:
1)What is the first step in DNA
replication?
2)What does the enzyme DNA
Polymerase do?
DNA Replication: Chunking
Your cells are constantly being replaced. Before
they can do so, they need to make more DNA
molecules for the nuclei of the new cells.
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1) What needs to happen before your
cells divide to make new cells?
Step 1:
DNA double helix is “unwound” and “unzipped” by an
enzyme called helicase.
This means the hydrogen bonds between the base pairs
are broken and the two strands are separated.… where
the two strands are separated is called the replication
fork.
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2) What does the enzyme helicase do?
Step 2:
As helicase moves down the DNA molecule, another enzyme is
also at work. DNA polymerase adds complementary
nucleotides – which are free floating in the nucleus – to the
separated strands of DNA to build new strands.
As the nucleotides are bonded to their pair with hydrogen bonds,
they also link up in a chain to form a new sugar-phosphate
backbone.
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3) DNA Polymerase adds
complementary bases to the parent
strands of DNA. Where do these
nucleotides come from?
Step 3:
DNA polymerase is also responsible for
“proofreading” and fixing any errors that were
made.
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4) DNA Polymerase has a second
important job. What is that job?
Step 4:
When replication is complete,
the enzymes fall off the DNA.
In the end, there are two DNA
double helices, each one
containing one original strand
and one new strand of DNA.
Having one old strand and one
new strand is called semiconservative replication.
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5) What does the
term semiconservative
replication mean?
Possible Cancer:
Only one in BILLIONS of replications will have a mistake that isn’t
caught.
When this happens it’s called a mutation. Each time the new DNA
replicates after that to make new cells, the error will be replicated
too.
Each new cell will have the mutation. If the mutation is harmless,
it’s not a big deal. If the mutation is in particular genes, it could
lead to Cancer.
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6) What is one possible side effect
of DNA mutations?
Chromosomes & DNA Replication 3D Animation (first 3 min)
https://www.youtube.com/watch?v=yqESR7E4b_8
(DNA Replication above different narrator)
https://www.youtube.com/watch?v=5VefaI0LrgE
Leading & Lagging Strands (4 min)
https://www.youtube.com/watch?v=OnuspQG0Jd0
Silent DNA (2 min)
https://www.youtube.com/watch?v=vNXFk_d6y80
Candy DNA Stop Motion (3 min)
https://www.youtube.com/watch?v=hC_8y8fNkCw