DNA structure diagram with coloring instructions for educational purposes.

Let’s go step by step to solve this DNA coloring task.

We’re working with a diagram of DNA — the double helix. It has two strands, and each strand is made of repeating units called nucleotides. Each nucleotide has three parts:
- A sugar (deoxyribose)
- A phosphate group
- A nitrogen base (A, T, C, or G)

The bases pair up in the middle: A always pairs with T, and C always pairs with G. They’re held together by hydrogen bonds — 2 between A-T, and 3 between C-G.

Now let’s follow the steps given in the worksheet.

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Step 1: Color the backbone

The “backbone” of DNA is made of alternating sugar and phosphate groups on the outside of the helix.

→ The instructions say:
- Color each Deoxyribose sugar RED
- Color each Phosphate group BLUE

So look at the outer edges of the DNA ladder — you’ll see shapes that are part of the sides. Those are the sugars and phosphates. Alternate them as you go down each side: red for sugar, blue for phosphate, red, blue, etc.

Note: In most diagrams, the pentagon-shaped pieces are the sugars, and the circles or rectangles connecting them are the phosphates. But since we can’t see colors here, just remember: every other piece along the side should be colored red (sugar) and blue (phosphate).

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Step 2: Color the nitrogen bases

These are the rungs of the ladder — the parts sticking inward from each side and pairing in the middle.

Instructions:

→ Color the pyrimidines ORANGE
Pyrimidines = Cytosine (C) and Thymine (T)

→ Color the purines GREEN
Purines = Adenine (A) and Guanine (G)

Wait — actually, looking again at your text:

It says:
> Color the pyrimidines ORANGE
> Color the adenines GREEN
> Color the guanines PURPLE
> Color the cytosines YELLOW

Hmm — that seems inconsistent with standard purine/pyrimidine grouping, but we must follow what’s written.

Actually, re-reading carefully:

Your Step 2 says:

> Color the pyrimidines ORANGE → so C and T should be orange?
But then it separately says:
> Color the adenines GREEN
> Color the guanines PURPLE
> Color the cytosines YELLOW

That means they want us to color each base individually, not by chemical class.

So ignore the word “pyrimidines” if it conflicts — because then it lists specific colors for each base.

Let me clarify based on exact wording:

From your image text:

> Step 2
> Color the pyrimidines ORANGE ← maybe this is a mistake? Because then it says:
> Color the adenines GREEN
> Color the guanines PURPLE
> Color the cytosines YELLOW

And thymine isn't mentioned after "pyrimidines". That suggests perhaps “Color the pyrimidines ORANGE” was meant to apply only to thymine? Or maybe it's an error.

Wait — let’s think logically.

In reality:
- Pyrimidines = C and T
- Purines = A and G

But the next lines assign individual colors:
- Adenine → GREEN
- Guanine → PURPLE
- Cytosine → YELLOW

Then what about Thymine? It wasn’t assigned a separate color — unless “Color the pyrimidines ORANGE” includes both C and T... but then C is also told to be YELLOW. Conflict!

This must be a typo or mislabeling in the worksheet.

Looking again at your original text:

You wrote:

> Step 2
> Color the pyrimidines ORANGE
> Color the adenines GREEN
> Color the guanines PURPLE
> Color the cytosines YELLOW

Ah — probably “Color the pyrimidines ORANGE” is meant to refer to THYMINE only? Because otherwise cytosine would have two colors.

Alternatively, maybe “pyrimidines” here refers to thymine, and cytosine is listed separately.

But scientifically, both C and T are pyrimidines.

Given the confusion, I think the intended instruction is:

Each base gets its own color:

- Adenine (A) → GREEN
- Guanine (G) → PURPLE
- Cytosine (C) → YELLOW
- Thymine (T) → ORANGE ← since it’s the only pyrimidine left unassigned

Yes — that makes sense. So even though C is also a pyrimidine, the worksheet wants:

→ A = GREEN
→ G = PURPLE
→ C = YELLOW
→ T = ORANGE

Because otherwise there’s overlap.

Also, note: in the diagram, wherever you see a base labeled or shaped like A, color it green; G → purple; C → yellow; T → orange.

Remember: A pairs with T, G pairs with C.

So if one side has a green base (A), the opposite side must have an orange base (T). If one side has purple (G), the other must have yellow (C).

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Step 3: Color the hydrogen bonds

Hydrogen bonds connect the base pairs in the middle.

Instructions:

> Color the ___ hydrogen bonds between A and T BLACK
> Color the ___ hydrogen bonds between G and C WHITE

How many hydrogen bonds?

Standard biology fact:
- Between A and T → 2 hydrogen bonds
- Between G and C → 3 hydrogen bonds

So fill in the blanks:

→ Color the 2 hydrogen bonds between A and T BLACK
→ Color the 3 hydrogen bonds between G and C WHITE

In the diagram, between each paired base, you’ll see dotted or solid lines representing these bonds. Count how many lines are between each pair.

If it’s an A-T pair, there should be 2 lines → color them black.
If it’s a G-C pair, there should be 3 lines → color them white.

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Now, putting it all together:

✔ Final Answer Summary:

Step 1:
- Deoxyribose sugars → RED
- Phosphate groups → BLUE

Step 2:
- Adenine (A) → GREEN
- Guanine (G) → PURPLE
- Cytosine (C) → YELLOW
- Thymine (T) → ORANGE

*(Note: Even though C and T are both pyrimidines, the worksheet assigns different colors — so follow the individual assignments.)*

Step 3:
- Hydrogen bonds between A and T → 2 bonds → color BLACK
- Hydrogen bonds between G and C → 3 bonds → color WHITE

Make sure when coloring the bases, you match the correct pairs: A with T, G with C. And check that the number of hydrogen bonds matches the pair type.

Final Answer:
Step 1: Sugars = Red, Phosphates = Blue
Step 2: Adenine = Green, Guanine = Purple, Cytosine = Yellow, Thymine = Orange
Step 3: A-T bonds (2) = Black, G-C bonds (3) = White