Question

9. Looking at DNA changes more closely, use the If the DNA sequence is TAC, what will the RNA codon be? What amino acid and/or function does this RNA codon code for? What RNA codon(s) code for the amino acid arginine (ARG)? What RNA codon codes for tryptophan (TRP)? What was the DNA sequence that was transcribed to make this codon? (backwards transcribe it) If the last nucleotide (letter) in the TRP codon changes to a "U," will the amino acid stay the same, or what change will occur? If the last nucleotide (letter) in the TRP codon changes to an "A." will the amino acid stay the same, or what change will occur? What term describes a change in DNA that is very small, and only one or two nucleotides have changed from the original sequence?

Answer 1

ANSWERS

1 -

• If the DNA sequence is TAC, then the RNA codon is AUG, which is the genetic code of methionine amino acid.
• AUG/methionine functions as a start codon in the transcribed mRNA that undergoes translation.

2 -

• RNA codon for amino acid ARGININE(ARG) are CGU, CGC, CGA, CGG, AGA, AGG

3 -

• RNA codon for tryptophan is UGG
• DNA sequence for UGG(uracil-guanine-guanine) is ACC (adenine-cytosine-cytosine)

4 -

• If the last NUCLEOTIDE letter of UGG changes into UGU then its amino acid also changes into cysteine from tryptophan

5-

• If the last NUCLEOTIDE letter of UGG changes into UGA then its FUNCTION changes and becomes a STOP-CODON.

6-

• MUTATION is the term describes a change in DNA that is very small, even only one or two nucleotides have changed from the original sequence