Question

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

To create a flow chart that demonstrates how genetic changes are created during DNA replication, you can use the following outline:

Flow Chart Outline

1. Start: DNA Replication

   • Description: The process where DNA makes a copy of itself.

2. Unwinding of DNA Helix

   • Enzyme involved: DNA helicase
   • Concept: The double helix unwinds into two single strands.

3. Template Strand Formation

   • Description: Each original strand serves as a template for a new complementary strand.
   • Note: Base pairing rules apply (A-T and C-G).

4. Nucleotide Pairing

   • Description: New nucleotides are added to the growing strand.
   • Base Pairing:
     • Adenine (A) pairs with Thymine (T)
     • Cytosine (C) pairs with Guanine (G)

5. Mutations Introduction

   • Occur during:
     • DNA polymerase adding nucleotides
     • Environmental causes (e.g., chemicals, radiation)
   • Types of mutations: substitutions, insertions, deletions

6. Proofreading and Repair

   • Enzyme involved: DNA polymerase also has a proofreading function.
   • Description: Corrects errors and removes incorrect nucleotides.

7. End of Replication

   • Result: Two identical DNA molecules are created.

8. Environmental Factors Impact

   • Description: Factors like UV light, chemicals, and radiation can cause mutations.
   • Where: At any DNA site during replication or any time within the life of the organism.

9. Genetic Variation Through Meiosis

   • Crossing-over:
     • Description: Exchanges genetic material between homologous chromosomes during prophase I.
   • Independent Assortment:
     • Description: Random distribution of maternal and paternal chromosomes into gametes during metaphase I.

10. Final Output: Genetic Variation

    • Description: Results in unique combinations of genes in offspring.

Answering the Questions

1. Where would a mutation be introduced during replication?

   • Mutations can be introduced during the addition of nucleotides by DNA polymerase when it incorrectly pairs a nucleotide. They can also arise from external environmental factors affecting the DNA.

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 can cause mutations at any point during DNA replication or in existing sequences at any time, such as exposure to UV light or chemical agents.

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

   • Crossing-over allows for the exchange of genetic material between homologous chromosomes, creating new allele combinations. Independent assortment leads to the random segregation of chromosomes into gametes, further contributing to genetic diversity in offspring.

Next Steps

• Review the flowchart and the processes involved in DNA replication, transcription, and translation.
• Discuss any unclear concepts with your Learning Coach.
• Consider doing the "Try This" activity for hands-on understanding or exploring additional resources for deeper insight.
• Focus review on areas where you feel less confident, such as mutation types or the specifics of meiosis.