DNA Replication
Every time a cell divides, it copies its DNA and passes one copy to each daughter cell. This process of creating a copy of the DNA is called DNA replication.
It begins during the S phase of the cell cycle, when the DNA helix starts to unwind.
The enzyme DNA helicase acts like a zipper, breaking the base pair bonds and separating the two strands.
Now, one of the separated strands serves as a template for the formation of a new strand.
Another enzyme, DNA polymerase, moves along the template strand, reading the bases and adding complementary nucleotides to build the new strand. Special base-pairing rules ensure the correct order—adenine pairs with thymine, and guanine pairs with cytosine.
Once completed, each new double-stranded DNA molecule has one old and one new strand. This process is called semiconservative replication because half of the original DNA is conserved in each new copy.
DNA Replication
DNA replication is the process by which a cell makes an exact copy of its DNA before cell division. This process ensures that each daughter cell receives identical genetic information. DNA replication follows a semi-conservative model, where the two new DNA molecules retain one original strand and incorporate one newly synthesized strand. Key enzymes like helicase, DNA polymerase, and ligase play critical roles in unwinding the DNA helix, assembling new strands, and sealing fragments.
Science and Engineering Practices (SEP): Planning and Carrying Out Investigations
By designing models and hands-on activities, students can visualize the steps of DNA replication and gain a deeper understanding of this essential biological process. Investigations may involve creating physical or interactive models to demonstrate how complementary base pairing ensures accuracy, how enzymes facilitate strand formation, and how replication contributes to cell growth and repair.
Activity Ideas:
- Paper Model of DNA Replication: Cut out paper nucleotides (A, T, C, G) and simulate how new DNA strands form by matching base pairs.
- String and Bead Model: Use beads to represent nucleotides and demonstrate how DNA polymerase builds a complementary strand.
- Enzyme Simulation Game: Act out the roles of helicase, DNA polymerase, and other enzymes in the replication process.
By experimenting with different models, you can visualize how DNA copies itself to maintain genetic continuity.
Crosscutting Concept (CCC): Cause and Effect
Understanding the cause-and-effect relationships in DNA replication helps scientists develop treatments for genetic disorders, improve cancer therapies, and enhance gene-editing techniques.
- Cause: DNA polymerase inserts the wrong nucleotide during replication
- Effect: A mutation occurs in the genetic sequence, which may lead to a malfunctioning protein or disease.
- Cause: Exposure to mutagens (e.g., radiation, chemicals, UV light)
- Effect: Increased likelihood of DNA damage and mutations.
- Cause: A mutation occurs in a gene that regulates cell division
- Effect: Uncontrolled cell growth, potentially leading to cancer.
- Cause: A beneficial mutation occurs in a population
- Effect: Increased survival and adaptation through evolution.
By studying DNA replication, students learn about the precision required for cellular reproduction, the impact of replication errors, and the applications of replication technology in scientific and medical fields.
Every time a cell divides, it copies its DNA and passes one copy to each daughter cell. This process of creating a copy of the DNA is called DNA replication.
It begins during the S phase of the cell cycle, when the DNA helix starts to unwind.
The enzyme DNA helicase acts like a zipper, breaking the base pair bonds and separating the two strands.
Now, one of the separated strands serves as a template for the formation of a new strand.
Another enzyme, DNA polymerase, moves along the template strand, reading the bases and adding complementary nucleotides to build the new strand. Special base-pairing rules ensure the correct order—adenine pairs with thymine, and guanine pairs with cytosine.
Once completed, each new double-stranded DNA molecule has one old and one new strand. This process is called semiconservative replication because half of the original DNA is conserved in each new copy.
Every time a cell divides, it copies its DNA and passes one copy to each daughter cell. This process of creating a copy of the DNA is called DNA replication.
It begins during the S phase of the cell cycle, when the DNA helix starts to unwind.
The enzyme DNA helicase acts like a zipper, breaking the base pair bonds and separating the two strands.
Now, one of the separated strands serves as a template for the formation of a new strand.
Another enzyme, DNA polymerase, moves along the template strand, reading the bases and adding complementary nucleotides to build the new strand. Special base-pairing rules ensure the correct order—adenine pairs with thymine, and guanine pairs with cytosine.
Once completed, each new double-stranded DNA molecule has one old and one new strand. This process is called semiconservative replication because half of the original DNA is conserved in each new copy.
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