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Albino Cats

A group of students is investigating gene mutations. They learn about a mutation that causes albino traits in house cats. The image shows the physical appearance and 4 codons of a DNA sequence of a cat with the albino mutation and a cat without the albino mutation.

The house cat with an albino mutation has a white physical appearance, and the DNA sequence for it is CCT-CCT-CTG-CTG. The house cat without an albino mutation has a brown physical appearance, and the DNA sequence for it is CCC-TCC-TCT-GCT.

Multiple Choice Question
What are the mRNA codons for the albino cat?

A.
GGA GGA GAC GAC

B.
GGG AGG AGA CGA

C.
CCU CCU AUG AUG

D.
GGU GGU GUC GUC

1 answer

To determine the mRNA codons for the albino cat, we first need to transcribe the given DNA sequence (CCT-CCT-CTG-CTG) into its corresponding mRNA sequence.

In DNA, the base pairs are transcribed to mRNA as follows:

  • Adenine (A) in DNA pairs with Uracil (U) in mRNA
  • Thymine (T) in DNA pairs with Adenine (A) in mRNA
  • Cytosine (C) in DNA pairs with Guanine (G) in mRNA
  • Guanine (G) in DNA pairs with Cytosine (C) in mRNA

Now, let's transcribe the DNA sequence for the albino cat:

  1. CCT → GGA
  2. CCT → GGA
  3. CTG → CAG
  4. CTG → CAG

So, the mRNA codons would be:

  • CCT → GGA
  • CCT → GGA
  • CTG → CAG
  • CTG → CAG

Now, we can see that none of the choices exactly match this sequence. However, it looks like the options mix up the transcription a bit, but let's check one more time if there's a commonly made mistake in identifying codons (for instance, reading the codons incorrectly).

Given the listed answers, let’s check them:

A. GGA GGA GAC GAC B. GGG AGG AGA CGA C. CCU CCU AUG AUG D. GGU GGU GUC GUC

The best match for the expected sequence (GGA, GGA, CAG, CAG) is not present as an exact answer. However, checking the options can lead us to think perhaps one closer to even the errors made or common mutations.

Since GGA is a common transcription base in terms of phenotype appearance (white cats), among the available choices, A. GGA GGA GAC GAC has a logical connection, even if the second half diverges (the A or G while CAG suggests perhaps a mutation).

So based on this analysis:

The best answer is A. GGA GGA GAC GAC.