Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

10. Transcription

Overview of Transcription

Genetics

10. Transcription

Overview of Transcription

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1:58 minutes

Problem 11

Textbook Question

Refer to Table 13.1. Can you hypothesize why a synthetic RNA composed of a mixture of poly U poly A would not stimulate incorporation of ¹⁴C-phenylalanine into protein?

Verified step by step guidance

Understand the context: Synthetic RNAs, such as poly U (uracil) and poly A (adenine), are used in experiments to study the genetic code and protein synthesis. These RNAs serve as templates for ribosomes to assemble amino acids into proteins.

Recall the codon-amino acid relationship: Each codon (a sequence of three nucleotides) in mRNA specifies a particular amino acid. For example, the codon UUU codes for phenylalanine. The incorporation of ¹⁴C-phenylalanine into protein depends on the presence of codons that code for phenylalanine.

Analyze the synthetic RNA mixture: A mixture of poly U and poly A would produce random combinations of U and A in the RNA sequence. This means the codons generated would be combinations of U and A, such as UUU, UUA, UAU, AUU, AAA, etc.

Determine codons for phenylalanine: Phenylalanine is coded by UUU and UUC. In the synthetic RNA mixture, UUU may appear, but the presence of A in the mixture reduces the likelihood of forming UUU codons. Additionally, UUC cannot form because the synthetic RNA lacks cytosine (C).

Hypothesize the outcome: Since the synthetic RNA mixture does not consistently produce UUU codons and cannot produce UUC codons, the incorporation of ¹⁴C-phenylalanine into protein would be minimal or absent. This explains why the mixture does not stimulate phenylalanine incorporation effectively.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Role of mRNA in Protein Synthesis

Messenger RNA (mRNA) serves as the template for protein synthesis, carrying genetic information from DNA to ribosomes. The sequence of nucleotides in mRNA determines the order of amino acids in a protein. For effective translation, mRNA must contain codons that correspond to specific amino acids, which are essential for building functional proteins.

Codon-Amino Acid Relationship

Codons are sequences of three nucleotides in mRNA that specify particular amino acids during translation. Each amino acid is encoded by one or more codons, and the correct pairing is crucial for synthesizing proteins. A synthetic RNA composed solely of poly U (which codes for phenylalanine) and poly A (which does not code for any amino acid) lacks the necessary variety of codons to facilitate proper protein synthesis.

Importance of tRNA in Translation

Transfer RNA (tRNA) molecules are responsible for bringing the appropriate amino acids to the ribosome during protein synthesis. Each tRNA has an anticodon that pairs with a corresponding codon on the mRNA. If the synthetic RNA lacks a diverse set of codons, it will not attract the necessary tRNAs, leading to ineffective incorporation of amino acids like ¹⁴C-phenylalanine into proteins.

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