Download HANDOUT: CH 17 pt 1 Study

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CHAPTER 17 STUDY QUESTIONS, part 1: From Gene to Protein (p. 325-344)
1) Summarize the one gene – one polypeptide hypothesis.
2) List 3 ways in which RNA differs from DNA.
3) How do the processes of transcription and translation differ in prokaryotes and eukaryotes?
4) What is meant by template strand of DNA? Is this always the same strand of a given DNA molecule?
5) How many RNA nucleotides are necessary to code for a polypeptide that is 177 amino acids long? Explain.
6) Summarize Nirenberg’s experiment in which he began to “crack” the genetic code of mRNA codons. (see p. 330)
7) It is now known that 61 of the 64 triplets code for an amino acid.
a) What is the purpose of the mRNA codon: AUG?
b) What is the purpose of the 3 triplets that do not code for an amino acid?
8) Complete the chart below summarizing the changes made to a pre-mRNA molecule in eukaryotes.
(HINT: see notes!)
mRNA end
Description of modification
Function
5’ end
3’ end
introns / exons
9) Sketch and label a typical ribosome. (see figure 17.17b)
10) Summarize the role in protein synthesis of each of the enzymes/proteins/structures listed in the chart below.
Enzyme/protein/structure
Function in protein synthesis
RNA polymerase
Ribosomal sites:
*P site
*A site
*E site
Promoter
Terminator
TATA box
Spliceosome
Ribozymes
11) What is the purpose of polyribosomes?
12) List two cellular destinations for a protein (polypeptide) once it is completed.
13) What determines the cellular destination of a completed protein?
14) Complete the following table for the functions of the various types of RNA / RNA complexes in a eukaryotic cell.
Type of RNA
Function
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Small nuclear RNA (snRNA) /
snRNPs (a.k.a. “snurps”)
Signal recognition particle (SRP)
15) Compare and contrast the codon and anticodon?
16) What is the “reading frame”?
17) Sketch the general structure of transfer RNA. (see fig. 17.15a)
18) Why is the enzyme aminoacyl-tRNA synthetase important to translation and protein synthesis?
19) Label the diagram below to detail the termination of translation. (see fig. 17.20)
20) How can human cells make 75,000-100,000 different proteins, given that there are only about 20,000 human
genes?
21) Suppose X-rays caused a sequence change in the TATA box of a particular gene’s promoter. How would that
affect transcription of the gene? (see figure 17.8)