DNA - The Double Helix, Coloring Worksheet - Free Printable

The image you've uploaded appears to depict DNA replication, specifically the process of semi-conservative replication. Let's analyze and solve the problem step by step.

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🔬 Understanding the Image

We see:
- Two "old strands" (parental DNA strands) running in opposite directions (antiparallel).
- Each old strand is being used as a template to build a new complementary strand.
- The new nucleotides are shown as separate shapes (T, A, G, C), which need to be matched correctly based on base pairing rules.
- The diagram shows two daughter DNA molecules, each consisting of one old strand and one new strand.

This is a classic representation of semi-conservative replication, where each original strand serves as a template for a new complementary strand.

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🧩 Base Pairing Rules

In DNA:
- Adenine (A) pairs with Thymine (T) via two hydrogen bonds.
- Guanine (G) pairs with Cytosine (C) via three hydrogen bonds.

So, we need to complete the new strands by adding the correct complementary bases.

Let’s label the bases on the old strands and then determine what should go on the new strands.

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🔎 Step-by-Step Solution

Let’s trace both old strands from top to bottom.

#### Left Old Strand (5' → 3'):
Looking at the sequence of bases:

From top to bottom:
1. T
2. A
3. C
4. T
5. G
6. A
7. T
8. C

So the sequence is:
T-A-C-T-G-A-T-C

Since DNA strands are antiparallel, the new strand will be synthesized in the 3' → 5' direction (but read 5' → 3' for convention). But we just need to find the complementary base for each.

Complementary sequence (for the new strand):
- T → A
- A → T
- C → G
- T → A
- G → C
- A → T
- T → A
- C → G

So the new strand on the left should be:
A-T-G-A-C-T-A-G

But note: This is complementary and antiparallel — so if the old strand is 5'-TAC TGA TC-3', the new strand will be 3'-ATG ACT AG-5'. However, since we're drawing it as a new strand growing off the template, the sequence we draw should match this.

So the left new strand should have:
- A, T, G, A, C, T, A, G (from bottom to top, or top to bottom depending on orientation)

Wait — let's look at the image again.

The new strands are shown as individual nucleotides floating near the old strand. We need to fill in the missing bases.

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✔ Let's Fill in the New Strands

We’ll go through each position and add the correct complementary base.

#### Left Side:
Old strand (top to bottom):
1. T → needs A
2. A → needs T
3. C → needs G
4. T → needs A
5. G → needs C
6. A → needs T
7. T → needs A
8. C → needs G

So the new strand on the left should have:
- A, T, G, A, C, T, A, G (in order from top to bottom)

But in the diagram, these are already partially drawn. Look at the shape of the nucleotides — some are filled in, some are blank.

Actually, looking closely, the new strands are not yet completed — we must add the correct bases.

Similarly, on the right side:

#### Right Old Strand (top to bottom):
1. A → needs T
2. T → needs A
3. G → needs C
4. C → needs G
5. A → needs T
6. T → needs A
7. G → needs C
8. C → needs G

So the right new strand should have:
- T, A, C, G, T, A, C, G (top to bottom)

Now, let’s compare to the image.

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🔍 Final Answer: Complete the Missing Bases

We need to fill in the blanks in the new strands using base pairing.

For example:
- Where an A is on the old strand, the new strand must have T
- Where a T is on the old strand, the new strand must have A
- Where a G is on the old strand, the new strand must have C
- Where a C is on the old strand, the new strand must have G

So, each gap in the "New Strands" should be filled with the complementary base.

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✔ Summary of the Task

The task is likely:
> Complete the new DNA strands by filling in the correct complementary bases using base pairing rules.

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📌 Final Solution

To solve:
1. Identify each base on the old strand.
2. Add its complementary base to the new strand.
3. Ensure the new strand is antiparallel to the old strand.

For example:
- If the old strand has T, the new strand gets A
- If the old strand has A, the new strand gets T
- If the old strand has G, the new strand gets C
- If the old strand has C, the new strand gets G

You would fill in the blanks accordingly.

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💡 Educational Insight

This diagram illustrates:
- Semi-conservative replication: Each new DNA molecule has one old and one new strand.
- Antiparallel nature: One strand runs 5'→3', the other 3'→5'.
- Complementary base pairing: A-T and G-C.
- Replication fork: The Y-shaped region where DNA unwinds and new strands are made.

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✔ Conclusion

Solution: Fill in the missing bases on the "New Strands" using the rule:
- A ↔ T
- G ↔ C

So:
- For every T on the old strand, place A on the new strand.
- For every A, place T
- For every G, place C
- For every C, place G

This completes the DNA replication process accurately.

Let me know if you'd like a labeled version or a visual explanation!