Question

1. usher syndrome is a rare genetic disease that affects both hearing and vision. it causes deafness or hearing loss and an eye disease called retinitis pigmentosa (rp). usher syndrome is caused by a mutation inside of our optical (eye) genes. its an inherited genetic disease, which means these changed genes get passed down from parents to children. scientists have found 9 different genes that can cause usher syndrome. the main symptoms of usher syndrome are deafness or hearing loss and rp. the table below shows a fragment of the dna sequence in a person without usher syndrome and a person with usher syndrome.a. direction: transcribe and translate the original and mutated dna sequences below. 4 pts| original dna sequence | tac | ttt | tgg | tta | cag | cgc | tgc | aac | ctg | cca | cca | tga | atc | normal human eye || ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- || mrna sequence | | | | | | | | | | | | | | || amino acid sequence | | | | | | | | | | | | | | || mutated dna sequence | tac | ttt | tgg | tta | cag | cgc | tgc | atc | ctg | cca | cca | gga | atc | usher syndrome eye || mutated mrna sequence | | | | | | | | | | | | | | || mutated amino acid sequence | | | | | | | | | | | | | | |(handwritten content in the tables is retained as part of the original content:mrna sequence: aug aaa acc aac guc gcg acg uug gac ggu ccc uagamino acid sequence: met lys thr asn val val thr leu asp val gly pro stopmutated mrna sequence: aug aaa acc aac guc gcg uac gac ggu ccu uagmutated amino acid sequence: met lys thr asn ala ala stop stop gly pro)b. identify the type of mutation for usher syndrome and justify your reasoning. 2 pts18. although made from similar monomers, dna and rna have several key differences. identify and describe two major structural differences between dna and rna molecules. must be as detailed as it can be! 2 pts

Explanation:

For Question 17a:

Step1: Transcribe Original DNA to mRNA

RNA uses uracil (U) instead of thymine (T). Pair DNA bases to mRNA: A→U, T→A, C→G, G→C.
Original DNA: TAC TTT TGG TTA CAG CGC TGC AAC CTG CCA CCA TGA ATC
mRNA: $AUG\ AAA\ ACC\ AAU\ GUC\ GCG\ ACG\ UUG\ GAC\ GGU\ GGU\ ACU\ UAG$

Step2: Translate Original mRNA to amino acids

Use codon table to match mRNA codons to amino acids.
Amino Acid Sequence: $Met\ Lys\ Thr\ Asn\ Val\ Ala\ Thr\ Leu\ Asp\ Gly\ Gly\ Thr\ Stop$

Step3: Transcribe Mutated DNA to mRNA

Pair mutated DNA bases to mRNA (A→U, T→A, C→G, G→C).
Mutated DNA: TAC TTT TGG TTA CAG CGC TGC ATC CTG CCA CCA TGA ATC
mRNA: $AUG\ AAA\ ACC\ AAU\ GUC\ GCG\ ACG\ UAG\ GAC\ GGU\ GGU\ ACU\ UAG$

Step4: Translate Mutated mRNA to amino acids

Use codon table; note UAG is a stop codon.
Amino Acid Sequence: $Met\ Lys\ Thr\ Asn\ Val\ Ala\ Thr\ Stop$

The mutation converts a codon that codes for an amino acid (Leu, from mRNA UUG) into a premature stop codon (UAG). This truncates the protein early, altering its structure and function, which matches the frameshift-independent early termination of translation.

1. Sugar component: DNA uses deoxyribose, which lacks an oxygen atom on the 2' carbon of the sugar ring; RNA uses ribose, which has a hydroxyl (-OH) group on the 2' carbon. This makes RNA more reactive and less stable than DNA.
2. Nitrogenous base: DNA uses thymine (T) as a pyrimidine base; RNA uses uracil (U) instead. Thymine has a methyl group (-CH₃) that uracil lacks, which helps DNA maintain structural stability and reduces spontaneous mutations.

Answer:

• Original mRNA Sequence: $AUG\ AAA\ ACC\ AAU\ GUC\ GCG\ ACG\ UUG\ GAC\ GGU\ GGU\ ACU\ UAG$
• Original Amino Acid Sequence: $Met\ Lys\ Thr\ Asn\ Val\ Ala\ Thr\ Leu\ Asp\ Gly\ Gly\ Thr\ Stop$
• Mutated mRNA Sequence: $AUG\ AAA\ ACC\ AAU\ GUC\ GCG\ ACG\ UAG\ GAC\ GGU\ GGU\ ACU\ UAG$
• Mutated Amino Acid Sequence: $Met\ Lys\ Thr\ Asn\ Val\ Ala\ Thr\ Stop$

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For Question 17b: