26. Nucleic Acids and Protein Synthesis

Tuftsin is an immunostimulator tetrapeptide having the following sequence:

                                   Thr–Lys–Pro–Arg

Write a possible sequence for the gene (Informational & template strand) that codes for this tetrapeptide.

Tuftsin is an immunostimulator tetrapeptide having the following sequence:

                                   Thr–Lys–Pro–Arg

Write a possible sequence for the gene (Informational & template strand) that codes for this tetrapeptide.

What amino acid sequence is coded for by the mRNA base sequence CUC-AUU-CCA-UGC-GAC-GUA?

Gln-His-Pro-Gly is the sequence of a molecule known as progenitor thyrotropin-releasing hormone (pro-TRH). If we were searching for pro-TRH genes, we would need to know what sequence of bases in DNA we should be looking for. Use the following boxes to indicate answers to parts (a)–(d).

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a. What RNA sequence could code for these four amino acids?

What is an anticodon, and on what kind of nucleic acid is it found?

What tetrapeptide is synthesized from the informational DNA sequence G-T-C-A-G-T-A-C-G-T-T-A?

The codons UGA, UAA, and UAG do not code for amino acids. What is their role as codons in mRNA?

What are the three steps of translation?

The following sequence is a portion of the DNA template strand: TGT GGG GTT ATT b. What are the anticodons of the tRNAs?

The following is a segment of the DNA template that codes for human insulin: TTT GTG AAC CAA CAC CTG 

b. Write the three-letter and one-letter abbreviations for this corresponding peptide segment.

Consider the following segment of mRNA produced by the normal order of DNA nucleotides:

ACA UCA CGG GUA

e. What is the amino acid order if an insertion mutation adds a G to the beginning of the mRNA segment?

Consider the following segment of mRNA produced by the normal order of DNA nucleotides:

ACA UCA CGG GUA

f. What is the amino acid order if a deletion mutation removes the A at the beginning of the mRNA segment?

a. A point mutation in the mRNA for an enzyme results in the replacement of leucine with alanine in the resulting enzyme molecule. Why does this change in amino acids have little effect on the biological activity of the enzyme?

A specific virus contains RNA as its genetic material.

a. Why would reverse transcription be used in the life cycle of this type of virus?

A specific virus contains RNA as its genetic material.

b. What is the name of this type of virus?

How do protease inhibitors disrupt the life cycle of the HIV virus?

The following is a segment of the template strand of human BRCA1 gene:

TGG AAT TAT CTG CTC TTC GCG

b. Write the three-letter and one-letter abbreviations for the corresponding peptide segment.

What is the effect of a deletion mutation on the amino acid sequence of a polypeptide?

How is protein synthesis affected if the normal base sequence TTT in the DNA template strand is changed to TTC?

Consider the following segment of mRNA produced by the normal order of DNA nucleotides: ACA UCA CGG GUA

a. What is the amino acid order produced from this mRNA?

Consider the following segment of mRNA produced by the normal order of DNA nucleotides: ACA UCA CGG GUA

b. What is the amino acid order if a point mutation changes UCA to ACA?

 A polypeptide contains 36 amino acids. How many nucleotides would be found in the mRNA for this polypeptide?

a. A point mutation changes a codon in the mRNA for an enzyme from GCC to GCA. Why is there no change in the amino acid order in the protein?

b In sickle-cell anemia, a point mutation in the mRNA for hemoglobin results in the replacement of glutamate with valine in the resulting hemoglobin molecule. Why does the replacement of one amino acid cause such a drastic change in biological function?

The following is a segment of the template strand of human BRCA1 gene:

TGG AAT TAT CTG CTC TTC GCG

c. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?

Answer the following questions for the given section of DNA: (17.3, 17.4, 17.5)

c. Write the three-letter symbols for the amino acids that would go into the peptide from the mRNA you wrote in part b.

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Suppose a mutation occurs in the DNA section in problem 17.89, and the first base in the parent chain, adenine, is replaced by guanine. (17.3, 17.4, 17.5, 17.6)

c. Write the three-letter symbols for the amino acids that would go into the peptide from the mRNA you wrote in part b.

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Suppose a mutation occurs in the DNA section in problem 17.89, and the first base in the parent chain, adenine, is replaced by guanine. (17.3, 17.4, 17.5, 17.6)

a. What type of mutation has occurred?

Match each of the following processes (1 to 5) with one of the items (a to e): (17.3, 17.4, 17.5, 17.7, 17.8)

5. reverse transcription

a. amino acids are linked together

b. RNA template is used to synthesize DNA

c. helicase unwinds DNA

d. genetic information is transferred from DNA

e. sticky ends join new DNA segment

Suppose a mutation occurs in the DNA section in problem 17.89, and the first base in the parent chain, adenine, is replaced by guanine. (17.3, 17.4, 17.5, 17.6)

d. What effect, if any, might this mutation have on the structure and/or function of the resulting protein?

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:

5'CUU|AAA|CGA|GUU3'

c. Write the amino acid sequence if a mutation changes CGA to AGA. Is this likely to affect protein function?

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:

5'CUU|AAA|CGA|GUU3'

e. What happens to the protein sequence if an A is added to the beginning of the chain and the sequence changes to 5'ACU|UAA|ACG|AGU3'?

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:

5'ACA|UCA|CGG|GUA3'

c. Write the amino acid sequence if a mutation changes CGG to GGG. Is this likely to affect protein function?

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:

5'ACA|UCA|CGG|GUA3'

f. What happens to the protein sequence if the A is removed from the beginning of the chain and the sequence changes to 5'CAU|CAC|GGG3'?

Provide the three-letter amino acid sequence expected from each of the following mRNA segments: b. 5'UUU|CCC|UUU|CCC3'

Consider the following portion of mRNA produced by the normal order of DNA nucleotides: 5'CUU|AAA|CGA|GUU3' a. Write the amino acid sequence that would be produced from this mRNA.

ALLIED HEALTH What is the one-letter amino acid sequence formed from the following mRNA that codes for a pentapeptide that is an endorphin called Met-enkephalin?

5'AUG|UAC|GGU|GGA|UUU|AUG|UAA3'

ALLIED HEALTH

a. A base substitution changes a codon for an enzyme from GCC to GCA. Why is there no change in the amino acid order in the protein?

A protein contains 35 amino acids. How many nucleotides would be found in the mRNA code for this protein?

ALLIED HEALTH Oxytocin is a small peptide hormone involved in the process of birthing and lactation. It contains the nine amino acids shown.

CYIQNCPLG

a. How many nucleotides would be found in the mRNA for this protein?

ALLIED HEALTH Alpha-melanocyte stimulating hormone (α-MSH) is a 13-amino-acid peptide hormone responsible for pigmentations in hair and skin. Its peptide sequence is shown.

SYSMQHFRWGKPV

a. How many nucleotides would be found in the mRNA for this protein?

How does a vaccine protect against a viral disease?

Describe how restriction enzymes are used in recombinant DNA technology.

ALLIED HEALTH Alpha-melanocyte stimulating hormone (α-MSH) is a 13-amino-acid peptide hormone responsible for pigmentations in hair and skin. Its peptide sequence is shown.

SYSMQHFRWGKPV

b. Suggest an mRNA sequence for the peptide. Show the 5' and 3' ends.

ALLIED HEALTH Alpha-melanocyte stimulating hormone (α-MSH) is a 13-amino-acid peptide hormone responsible for pigmentations in hair and skin. Its peptide sequence is shown.

SYSMQHFRWGKPV

c. Suggest a complementary template DNA sequence based on the mRNA sequence suggested in part b.

Name two components common to all viruses.

CRISPR was first discovered as a defense mechanism in what organism?

Name the gene that tags other genes through fluorescent coloring.

Provide the three-letter amino acid sequence expected from each of the following mRNA segments:

b. 5'CUA|AGC|UUC|AAC|UGG3'

For each of the following, note whether the component can be found in a virus, a cell, or both.

c. ribosome

For each of the following, note whether the component can be found in a virus, a cell, or both.

c. capsid

For each of the following, note whether the component can be found in a virus, a cell, or both.

a. RNA