The diagram above shows the process of replication that was introduced in this unit. In your Science Notebook, create a flow chart that demonstrates how genetic changes are created during this process. Be sure to label any concepts that were also introduced in this unit. Use your flowchart and information to answer the following questions: Where would a mutation be introduced during replication? What nucleotide bases pair together to create new strands of DNA? Where do environmental factors impact DNA? How does crossing-over and independent assortment contribute to genetic variation? Review your flowchart and the answers to your questions with your Learning Coach. Discuss what the best next steps for you might be. Your Learning Coach might suggest you go back and review some lesson material. You might also choose to move on to the Try This activity

Answer 1

Creating a flowchart to illustrate the process of DNA replication, including genetic changes and concepts relevant to mutations, nucleotide pairing, and genetic variation, is a great way to visually summarize the key points.

Flowchart for DNA Replication and Genetic Change

1. Start: DNA Strands

   • Original DNA double helix

2. Unwinding of DNA

   • Enzymes (like helicase) unwind the double helix
   • Concept: Separation of strands

3. Template Strands

   • Each original strand serves as a template for a new strand

4. Nucleotide Pairing

   • Concept: A pairs with T, C pairs with G
   • New nucleotides are added to create complementary strands

5. Synthesis of New Strands

   • DNA polymerase synthesizes new DNA strands
   • Concept: Leading and lagging strand synthesis

6. Mutation Introduction (when applicable)

   • Mutations can occur during DNA replication if:
     • Incorrect nucleotide incorporation
     • Slippage during DNA replication
   • Concept: Types of mutations (e.g., point mutations, insertions, deletions)

7. Proofreading and Repair

   • DNA polymerase has proofreading ability to correct errors
   • Repair mechanisms act on mismatched bases

8. Completion of DNA Replication

   • Two identical double helices are formed

9. Contribution of Environmental Factors

   • Exposure to UV light, chemicals, or radiation can lead to DNA damage
   • This damage can lead to mutations if not repaired

10. Genetic Variation Mechanisms (during meiosis)

    • Crossing-over: Exchange of genetic material between homologous chromosomes
    • Independent assortment: Random combination of chromosomes during gamete formation

Key Questions

1. Where would a mutation be introduced during replication?

   • A mutation can be introduced during the nucleotide addition phase when DNA polymerase incorporates the wrong nucleotide or when slippage occurs during replication.

2. What nucleotide bases pair together to create new strands of DNA?

   • Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G).

3. Where do environmental factors impact DNA?

   • Environmental factors impact DNA during replication, causing damage that may lead to mutations, particularly if they occur during cell division or in highly reactive chemical environments.

4. How does crossing-over and independent assortment contribute to genetic variation?

   • Crossing-over allows chromosomes to exchange parts, combining genetic material from both parents, while independent assortment randomly separates chromosomes into gametes, ensuring that each gamete has a unique combination of alleles.

Next Steps

After reviewing this flowchart and addressing the questions, here are some suggested next steps:

• Consider revisiting key lessons on replication, mutation types, and mechanisms of genetic variation to reinforce your understanding.
• Discuss specific processes or terms with your Learning Coach if you're unclear about them.
• Engage in a "Try This" activity to apply this knowledge practically, such as simulating crossing-over or creating models of DNA sequences to demonstrate mutations.

Using this structured approach will help solidify your grasp on DNA replication and genetic changes while preparing you for further exploration of genetics.