DNA, Proteins, and Mutations - Free Printable

Let’s solve this step by step.

We are given two DNA sequences — one for a human and one for a cow — and we need to:

1. Find the complementary RNA strand for each (remember: in RNA, A pairs with U, T pairs with A, C pairs with G, G pairs with C).
2. Use the codon table (which you’d normally look up, but since it’s not provided here, I’ll use standard genetic code) to find the amino acids.
3. Compare the amino acid chains and count how many bases are different between the human and cow DNA.

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Step 1: Human DNA → Complementary RNA

Human DNA:
C C A T A G C A C G T T A C A A C G T G A A G G A A A

To make complementary RNA:
- Replace T with A
- Replace A with U
- Replace C with G
- Replace G with C

So:

DNA: C C A T A G C A C G T T A C A A C G T G A A G G A A A
RNA: G G U A U C G U G C A A U G U U G C A C U U C C U U U

Now let’s break into codons (groups of 3):

RNA Codons:
GGU | AUC | GUG | CAA | UGU | UGC | ACU | UCC | UUU

Now match to amino acids using standard genetic code:

- GGU → Glycine (Gly)
- AUC → Isoleucine (Ile)
- GUG → Valine (Val)
- CAA → Glutamine (Gln)
- UGU → Cysteine (Cys)
- UGC → Cysteine (Cys)
- ACU → Threonine (Thr)
- UCC → Serine (Ser)
- UUU → Phenylalanine (Phe)

✔ Human Amino Acid Chain:
Gly - Ile - Val - Gln - Cys - Cys - Thr - Ser - Phe

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Step 2: Cow DNA → Complementary RNA

Cow DNA:
C C A T A G C A T G T T A C A A C G C G A A G G G A C

Complementary RNA:

DNA: C C A T A G C A T G T T A C A A C G C G A A G G G A C
RNA: G G U A U C G U A C A A U G U U G C G C U U C C C U G

Codons:

GGU | AUC | GUA | CAA | UGU | UGC | GCU | UCC | CUG

Amino Acids:

- GGU → Glycine (Gly)
- AUC → Isoleucine (Ile)
- GUA → Valine (Val) ← same as GUG? Wait — actually, both GUG and GUA code for Valine! So still Val.
- CAA → Glutamine (Gln)
- UGU → Cysteine (Cys)
- UGC → Cysteine (Cys)
- GCU → Alanine (Ala) ← DIFFERENT from human’s Thr (ACU)
- UCC → Serine (Ser)
- CUG → Leucine (Leu) ← DIFFERENT from human’s Phe (UUU)

Wait — let me double-check:

Human had: ACU → Thr
Cow has: GCU → Ala → YES, different.

Human had: UUU → Phe
Cow has: CUG → Leu → YES, different.

Also check position 3: Human GUG → Val, Cow GUA → Val → SAME amino acid.

But wait — the question says “compare the DNA sequence and circle any single base that is different” — so maybe we should compare DNA first?

Actually, let’s re-read the instructions:

> 3. Compare the DNA Sequence and circle any single base that is different in the cow and human sequences. How many bases are different?

So we don’t care about amino acids for part 3 — just compare the original DNA strands base by base.

Let’s do that now.

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Step 3: Compare Human vs Cow DNA Base by Base

Write them aligned:

Position: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Human: C C A T A G C A C G T T A C A A C G T G A A G G A A A
Cow: C C A T A G C A T G T T A C A A C G C G A A G G G A C

Now go base by base:

Positions 1–6: identical (CCA TAG)
Position 7: C = C
Position 8: A = A
Position 9: C ≠ T → DIFFERENCE #1
Positions 10–18: GTT ACA ACG → all same
Position 19: T ≠ C → DIFFERENCE #2
Position 20: G = G
Position 21: A ≠ A? Wait — human is A, cow is A? No:

Wait — let's write full string without spaces:

Human DNA: CCATAGCACGTTACAACGTGAAGGAAA
Cow DNA: CCATAGCATGTTACAACGCGAAGGGAC

Let’s index them:

Index: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Human: C C A T A G C A C G T T A C A A C G T G A A G G A A A
Cow: C C A T A G C A T G T T A C A A C G C G A A G G G A C

Now compare:

Pos 1–8: same
Pos 9: Human=C, Cow=T → DIFF #1
Pos 10–18: same (GTTACAACG)
Pos 19: Human=T, Cow=C → DIFF #2
Pos 20: G=G
Pos 21: A=A
Pos 22: A=A
Pos 23: G=G
Pos 24: G=G
Pos 25: Human=A, Cow=G → DIFF #3
Pos 26: A=A
Pos 27: Human=A, Cow=C → DIFF #4

Wait — let’s list differences clearly:

- Position 9: C (human) vs T (cow) → diff
- Position 19: T (human) vs C (cow) → diff
- Position 25: A (human) vs G (cow) → diff
- Position 27: A (human) vs C (cow) → diff

That’s 4 differences.

But wait — let me count again carefully.

Full alignment:

Human: C C A T A G C A C G T T A C A A C G T G A A G G A A A
Cow: C C A T A G C A T G T T A C A A C G C G A A G G G A C

Compare each:

1: C=C
2: C=C
3: A=A
4: T=T
5: A=A
6: G=G
7: C=C
8: A=A
9: C≠T → 1
10: G=G
11: T=T
12: T=T
13: A=A
14: C=C
15: A=A
16: A=A
17: C=C
18: G=G
19: T≠C → 2
20: G=G
21: A=A
22: A=A
23: G=G
24: G=G
25: A≠G → 3
26: A=A
27: A≠C → 4

Yes — 4 bases are different.

Earlier I thought position 21 was different, but no — both are A.

And position 27: human ends with AAA, cow ends with GAC → last base A vs C → yes, different.

So total: 4 different bases.

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Final Answer:
4