Podcast
Questions and Answers
Cells must copy their DNA before they do what?
Cells must copy their DNA before they do what?
divide
During what part of the cell cycle is DNA copied?
During what part of the cell cycle is DNA copied?
S phase of interphase
In eukaryotes, where are the copies of the DNA made?
In eukaryotes, where are the copies of the DNA made?
the nucleus
The process of copying DNA is known as DNA ____
The process of copying DNA is known as DNA ____
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Replication of DNA begins at points called ____
Replication of DNA begins at points called ____
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The two DNA strands ____ at origins of replication forming Y-shaped areas called ____
The two DNA strands ____ at origins of replication forming Y-shaped areas called ____
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New DNA strands grow at the ____
New DNA strands grow at the ____
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As the two strands open at the origins of replication, replication ____ form
As the two strands open at the origins of replication, replication ____ form
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Prokaryotic (bacteria) chromosomes have a ___ replication bubble
Prokaryotic (bacteria) chromosomes have a ___ replication bubble
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Eukaryotic cells have ____ bubbles
Eukaryotic cells have ____ bubbles
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What enzyme uncoils DNA so it can be replicated or copied?
What enzyme uncoils DNA so it can be replicated or copied?
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What other job does helicase perform?
What other job does helicase perform?
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What is the job of single-strand binding proteins?
What is the job of single-strand binding proteins?
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A RNA ___ must be present to start the addition of new nucleotides
A RNA ___ must be present to start the addition of new nucleotides
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What enzyme makes the RNA primer?
What enzyme makes the RNA primer?
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DNA ___ is the enzyme that adds new complementary base pairs.
DNA ___ is the enzyme that adds new complementary base pairs.
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DNA polymerase can only add nucleotides to what end of the DNA molecule?
DNA polymerase can only add nucleotides to what end of the DNA molecule?
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Which DNA strand is synthesized continuously as a single strand?
Which DNA strand is synthesized continuously as a single strand?
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The leading strand is made from the _____ toward the ____ as it opens.
The leading strand is made from the _____ toward the ____ as it opens.
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The ___ strand is synthesized ____ the overall direction of replication.
The ___ strand is synthesized ____ the overall direction of replication.
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The lagging strand is made in ___ short segments from the ____ fork toward the ___ of replication.
The lagging strand is made in ___ short segments from the ____ fork toward the ___ of replication.
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The short segments of lagging strands are called ____
The short segments of lagging strands are called ____
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What enzyme joins Okazaki fragments together into one strand?
What enzyme joins Okazaki fragments together into one strand?
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DNA polymerase initially makes how many errors?
DNA polymerase initially makes how many errors?
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Proof-reading enzymes correct mistakes in DNA to one in ____ base pairing errors?
Proof-reading enzymes correct mistakes in DNA to one in ____ base pairing errors?
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Who developed this idea about replication?
Who developed this idea about replication?
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Chemicals and ____ radiation can damage DNA in our body cells so it must be ____ repaired.
Chemicals and ____ radiation can damage DNA in our body cells so it must be ____ repaired.
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________ occurs when any of over 50 repair enzymes remove damaged parts of DNA.
________ occurs when any of over 50 repair enzymes remove damaged parts of DNA.
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What 2 enzymes replace damaged sections of DNA and rebind the molecule?
What 2 enzymes replace damaged sections of DNA and rebind the molecule?
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Study Notes
Overview of DNA Replication
- Cells must copy DNA before cell division to ensure new cells receive identical DNA strands.
- The DNA copying process occurs during the S phase of interphase.
Location and Initiation
- In eukaryotes, DNA replication occurs in the nucleus.
- The process starts at specific sites called the Origin of Replication.
Replication Forks and Bubbles
- DNA strands separate at origins of replication, forming Y-shaped structures known as replication forks.
- New DNA strands elongate at these forks, creating replication bubbles as the strands open.
Prokaryotic vs Eukaryotic Replication
- Prokaryotic cells feature a single replication bubble.
- Eukaryotic cells have multiple replication bubbles.
Key Enzymes in DNA Replication
- Helicase uncoils DNA and separates double-stranded DNA by breaking hydrogen bonds.
- Single-strand binding proteins keep DNA strands apart and prevent them from reattaching.
- Primase synthesizes a small RNA primer, essential for starting nucleotide addition.
- DNA Polymerase adds complementary base pairs to the growing DNA strand and works primarily at the 3' end.
Leading and Lagging Strands
- The leading strand is synthesized continuously from the origin toward the opening replication fork.
- The lagging strand is synthesized discontinuously in short segments called Okazaki fragments, moving from the replication fork toward the origin.
Joining and Correcting
- DNA ligase connects Okazaki fragments into a complete strand.
- During replication, DNA Polymerase makes an error rate of 1 in 10,000 nucleotides, which is reduced to 1 in one billion due to proofreading enzymes.
Historical Context and Damage Repair
- The model of DNA replication was proposed by Watson and Crick.
- DNA can be damaged by chemicals and ultraviolet radiation, necessitating continuous repair.
- Excision repair is a mechanism where over 50 different enzymes remove and repair damaged DNA sections.
- DNA Polymerase and ligase are responsible for replacing damaged DNA and reconstructing the DNA molecule.
Studying That Suits You
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Description
Test your knowledge of DNA replication with these flashcards. The quiz covers essential concepts such as the cell cycle, the S phase, and where DNA replication occurs in eukaryotic cells. Perfect for students studying biology or preparing for exams.
