DNA Replication
DNA Replication
Cell Cycle- Interphase (S phase)
Honors Biology
Mrs. Sims
Let’s Start with a Video
Please view the video before you start this
presentation.
DNA Replication Animation
**This animation is created by McGraw Hill, the publisher of
your textbook.
Focus Questions
18) What does the ending –ase
tell about a molecule?
19) In which direction does DNA
replicate?
20) Why does one strand
replicate faster and one slower?
Replication copies the genetic
information.
A single strand of DNA
serves as a template for a
new strand.
The rules of base pairing
direct replication.
DNA is replicated during
the S (synthesis) stage of
the cell cycle.
Each body cell gets a
complete set of
identical DNA.
Prokaryotes vs. Eukaryotes
Prokaryotes
have ONE
point of Origin
on their
circular
chromosome
Eukaryotes
have MANY
on their linear
chromosomes!
Prokaryotes:
Eukaryotes:
Alternative Models of DNA Replication
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Mutations
DNA Polymerase
has an error rate of only 1 wrong
nucleotide per 100,000!
Mutations
are any change in DNA sequence and
can be caused by mutagen
A
mutagen
is any chemical or environmental
condition that causes a mutation
Point Mutations
– mutations in a single nucleotide
base
Substitution
– one nucleotide substituted for
another
Insertion
– one nucleotide is inserted into the
sequence
Deletion
– one nucleotide is deleted from the
sequence
DNA Replication
1)
DNA Helicase
attaches to DNA and breaks the hydrogen
bonds between bases to unwind it.
2)
Primase
puts down an RNA primer for DNA Polymerase to
attach nucleotides to.
3)
DNA Polymerase III
adds nucleotides moving towards the 5’
end of the template strand building the new strand from the 5’
to 3’ direction.
Leading strand is continuous
Lagging Strand is slower, discontinuous and creates
Okazaki
Fragments
4)
DNA Polymerase I
removes the RNA primers and replaces
them with DNA nucleotides.
5)
Ligase
covalently bonds the replaced DNA nucleotides
together.
1)
DNA Helicase
attaches to DNA and breaks the hydrogen
bonds between bases to unwind it, creating a
Replication Fork
.
2)
Primase
puts down an
RNA primer
for
DNA Polymerase III
to
attach nucleotides to.
3)
DNA Polymerase III
adds nucleotides moving towards the 5’
end of the strand it is on, so it builds the new strand from the 5’
to 3’ direction.
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4) DNA Polymerase I
removes the
RNA primers
and replaces
them with DNA nucleotides.
5) DNA Ligase
covalently bonds the replaced DNA nucleotides
together.
Helicase
DNA Polymerase III
Focus Questions
21) What are the three ways in which DNA was
hypothesized to replicate? Which is the actual
method?
22) What scientists performed an experiment to
determine the way in which DNA replicates?
23) What are the two different strands involved
in DNA replication and which strand is
replicated faster?
24) Why is there a difference between the
replication rate of each strand? (Describe in
terms of replication direction and continuity.)
DNA Replication in Real Time
https://www.youtube.com/watch?v=yqESR7E4b_8
This content delves into the intricate process of DNA replication during the S phase of the cell cycle, exploring key concepts such as genetic information copying, base pairing rules, prokaryotic vs. eukaryotic replication differences, alternative models of replication, mutations, and the steps involved in DNA replication. It also provides focus questions and visuals to aid in understanding the fundamental aspects of DNA replication.
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Presentation Transcript
DNA Replication Cell Cycle- Interphase (S phase) Honors Biology Mrs. Sims
Lets Start with a Video Please view the video before you start this presentation. DNA Replication Animation **This animation is created by McGraw Hill, the publisher of your textbook.
Focus Questions 18) What does the ending ase tell about a molecule? 19) In which direction does DNA replicate? 20) Why does one strand replicate faster and one slower?
Replication copies the genetic information. A single strand of DNA serves as a template for a new strand. The rules of base pairing direct replication. DNA is replicated during the S (synthesis) stage of the cell cycle. Each body cell gets a complete set of identical DNA.
Prokaryotes vs. Eukaryotes Prokaryotes: Prokaryotes have ONE point of Origin on their circular chromosome Eukaryotes have MANY on their linear chromosomes! Eukaryotes:
Semiconservative replication Parental DNA First generation Second generation
Mutations DNA Polymerase has an error rate of only 1 wrong nucleotide per 100,000! Mutations are any change in DNA sequence and can be caused by mutagen A mutagen is any chemical or environmental condition that causes a mutation Point Mutations mutations in a single nucleotide base Substitution one nucleotide substituted for another Insertion one nucleotide is inserted into the sequence Deletion one nucleotide is deleted from the sequence
DNA Replication 1) DNA Helicase attaches to DNA and breaks the hydrogen bonds between bases to unwind it. 2) Primase puts down an RNA primer for DNA Polymerase to attach nucleotides to. 3) DNA Polymerase III adds nucleotides moving towards the 5 end of the template strand building the new strand from the 5 to 3 direction. Leading strand is continuous Lagging Strand is slower, discontinuous and creates Okazaki Fragments 4) DNA Polymerase I removes the RNA primers and replaces them with DNA nucleotides. 5) Ligase covalently bonds the replaced DNA nucleotides together.
1) DNA Helicase attaches to DNA and breaks the hydrogen bonds between bases to unwind it, creating a Replication Fork. Primase puts down an RNA primer for DNA Polymerase III to attach nucleotides to. DNA Polymerase III adds nucleotides moving towards the 5 end of the strand it is on, so it builds the new strand from the 5 to 3 direction. 2) 3) Leading strand 1 DNA helix RNA primer DNA polymerase Replication fork (Helicase unwinding) Lagging strand (first Okazaki fragment) Direction of replication
DNA Polymerase III adds nucleotides to the Leading and Lagging strands as it moves towards the 5 end of each strand it is using as a template. This creates Okazaki Fragments on the Lagging strand. Leading strand Primase: makes RNA primers 2 Two Okazaki fragments
4) DNA Polymerase I removes the RNA primers and replaces them with DNA nucleotides. 5) DNA Ligase covalently bonds the replaced DNA nucleotides together. Leading strand DNA Polymerase III 3 Helicase DNA Polymerase I Third Okazaki fragment DNA ligase RNA primer (Primase) Lagging strand
Focus Questions 21) What are the three ways in which DNA was hypothesized to replicate? Which is the actual method? 22) What scientists performed an experiment to determine the way in which DNA replicates? 23) What are the two different strands involved in DNA replication and which strand is replicated faster? 24) Why is there a difference between the replication rate of each strand? (Describe in terms of replication direction and continuity.)
DNA Replication in Real Time https://www.youtube.com/watch?v=yqESR7E4b_8
