Ch. 14 - Translation and Proteins
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Problem 1
In this chapter, we focused on the translation of mRNA into proteins as well as on protein structure and function. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations in the chapter, what answers would you propose to the following fundamental questions:
What experimentally derived information led to Holley's proposal of the two-dimensional cloverleaf model of tRNA?- In this chapter, we focused on the translation of mRNA into proteins as well as on protein structure and function. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations in the chapter, what answers would you propose to the following fundamental questions: How do we know that the structure of a protein is intimately related to the function of that protein?
Problem 1
- In this chapter, we focused on the genetic code and the transcription of genetic information stored in DNA into complementary RNA molecules. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions: Why did geneticists believe, even before direct experimental evidence was obtained, that the genetic code would turn out to be composed of triplet sequences and be nonoverlapping? Experimentally, how were these suppositions shown to be correct?
Problem 1
- In this chapter, we focused on the genetic code and the transcription of genetic information stored in DNA into complementary RNA molecules. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions: What experimental evidence provided the initial insights into the compositions of codons encoding specific amino acids?
Problem 1
- In this chapter, we focused on the genetic code and the transcription of genetic information stored in DNA into complementary RNA molecules. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions: How were the specific sequences of triplet codes determined experimentally?
Problem 1
- In this chapter, we focused on the genetic code and the transcription of genetic information stored in DNA into complementary RNA molecules. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions: How were the experimentally derived triplet codon assignments verified in studies using bacteriophage MS2?
Problem 1
- In this chapter, we focused on the translation of mRNA into proteins as well as on protein structure and function. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations in the chapter, what answers would you propose to the following fundamental questions: How do we know, based on studies of Neurospora nutritional mutations, that one gene specifies one enzyme?
Problem 1
- In this chapter, we focused on the translation of mRNA into proteins as well as on protein structure and function. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations in the chapter, what answers would you propose to the following fundamental questions: What experimental information verifies that certain codons in mRNA specify chain termination during translation?
Problem 1
- In this chapter, we focused on the translation of mRNA into proteins as well as on protein structure and function. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations in the chapter, what answers would you propose to the following fundamental questions: On what basis have we concluded that proteins are the end products of genetic expression?
Problem 1
- Write a short essay that discusses the role of ribosomes in the process of translation as it relates to these concepts.
Problem 2
- Write a short essay that summarizes the key properties of the genetic code and the process by which RNA is transcribed on a DNA template.
Problem 2
- Assuming the genetic code is a triplet, what effect would the addition or loss of two nucleotides have on the reading frame? The addition or loss of three, six, or nine nucleotides?
Problem 3
- Contrast the roles of tRNA and mRNA during translation, and list all enzymes that participate in the transcription and translation process.
Problem 3
- The mRNA formed from the repeating tetranucleotide UUAC incorporates only three amino acids, but the use of UAUC incorporates four amino acids. Why?
Problem 4
- Francis Crick proposed the 'adaptor hypothesis' for the function of tRNA. Why did he choose that description?
Problem 4
- In studies using repeating copolymers, AC . . . incorporates threonine and histidine, and CAACAA . . . incorporates glutamine, asparagine, and threonine. What triplet code can definitely be assigned to threonine?
Problem 5
- During translation, what molecule bears the codon? the anticodon?
Problem 5
- In a coding experiment using repeating copolymers (as demonstrated in Table 13.3), the following data were obtained: Copolymer Codons Produced Amino Acids in Polypeptide AG AGA, GAG Arg, Glu AAG AGA, AAG, GAA Lys, Arg, Glu AGG is known to code for arginine. Taking into account the wobble hypothesis, assign each of the four codons produced in the experiment to its correct amino acid.
Problem 6
- The α chain of eukaryotic hemoglobin is composed of 141 amino acids. What is the minimum number of nucleotides in an mRNA coding for this polypeptide chain?
Problem 6
- In the triplet binding technique, radioactivity remains on the filter when the amino acid corresponding to the codon is labeled. Explain the rationale for this technique.
Problem 7
- Assuming that each nucleotide in an mRNA is 0.34 nm long, how many triplet codes can simultaneously occupy the space in a ribosome that is 20 nm in diameter?
Problem 7
- Describe the central dogma of molecular genetics and how it serves as the basis of modern genetics.
Problem 8
- Summarize the steps involved in charging tRNAs with their appropriate amino acids.
Problem 8
- How many different proteins, each with a unique amino acid sequence, can be constructed that have a length of five amino acids?
Problem 9
- To carry out its role, each transfer RNA requires at least four specific recognition sites that must be inherent in its tertiary structure. What are they?
Problem 9
- What are isoaccepting tRNAs? Assuming that there are only 20 different aminoacyl tRNA synthetases but 31 different tRNAs, speculate on parameters that might be used to ensure that each charged tRNA has received the correct amino acid.
Problem 10
- When a codon in an mRNA with the sequence 5'-UAA-3' enters the A site of a ribosome, it is not recognized by a tRNA with a complementary anticodon. Why not? What recognizes it instead?
Problem 11
Problem 12
Predict the amino acid sequence produced during translation by the following short hypothetical mRNA sequences (note that the second sequence was formed from the first by a deletion of only one nucleotide):
Sequence 1: 5'-AUGCCGGAUUAUAGUUGA-3'
Sequence 2: 5'-AUGCCGGAUUAAGUUGA-3'
What type of mutation gave rise to sequence 2?- Discuss the potential difficulties of designing a diet to alleviate the symptoms of phenylketonuria.
Problem 12
Problem 13
A short RNA molecule was isolated that demonstrated a hyperchromic shift (see Chapter 10), indicating secondary structure. Its sequence was determined to be
5'-AGGCGCCGACUCUACU-3'
If the molecule were an internal part of a message, what amino acid sequence would result from it following translation? (Refer to the code chart in Figure 13.7.)
