Chapter 13 Flashcards
1) A protein is 300 amino acids long. Which of the following could be the number of nucleotides in the section of DNA that codes for this protein? (Remember: DNA is double-stranded.) A) 3 B) 100 C) 300 D) 500 E) 1800
E) 1800
2) A short segment of an mRNA molecule is shown below. The polypeptide it codes for is also shown:
5’-AUGGUGCUGAAG : methionine-valine-leucine-lysine
Assume that a mutation in the DNA occurs so that the fourth base (counting from the 5’ end) of the messenger RNA now reads A rather than G. What sequence of amino acids will the mRNA now code for? (You do not need a copy of the genetic code to answer the question.)
A) methionine-valine-leucine-lysine
B) methionine-lysine-leucine-lysine
C) methionine-leucine-leucine-lysine
D) methionine-valine-methionine-lysine
E) methionine-methionine-leucine-lysine
E) methionine-methionine-leucine-lysine
3) The term peptidyl transferase relates to ________.
A) base additions during mRNA synthesis
B) peptide bond formation during protein synthesis
C) elongation factors binding to the large ribosomal subunit
D) discontinuous strand replication
E) 5’ capping of mRNA
B) peptide bond formation during protein synthesis
4) Which of the following are among the major components of prokaryotic ribosomes? A) 12S rRNA, 5.8S rRNA, and proteins B) 16S rRNA, 5.8S rRNA, and 28S rRNA C) 16S rRNA, 5S rRNA, and 23S rRNA D) lipids and carbohydrates E) 18S rRNA, 5.8S rRNA, and proteins
C) 16S rRNA, 5S rRNA, and 23S rRNA
5) The one-gene:one-enzyme hypothesis emerged from work on which two organisms?
A) E. coli and yeast
B) Drosophila and humans
C) Neurospora and Drosophila
D) E. coli and humans
E) All of the answers listed are correct.
C) Neurospora and Drosophila
6) By their experimentation using the Neurospora fungus, Beadle and Tatum were able to propose the far-reaching hypothesis that ________.
A) prototrophs will grow only if provided with nutritional supplements
B) several different enzymes may be involved in the same step in a biochemical pathway
C) the role of a specific gene is to produce a specific enzyme
D) genetic recombination occurred in Neurospora
E) more than one codon can specify a given amino acid
C) the role of a specific gene is to produce a specific enzyme
7) The β chain of adult hemoglobin is composed of 146 amino acids of a known sequence. In comparing the normal β chain with the β chain in sickle cell hemoglobin, what alteration is one likely to find?
A) valine instead of glutamic acid in the sixth position
B) glutamic acid replacing valine in the first position
C) extensive amino acid substitutions
D) trinucleotide repeats
E) frameshift substitutions
A) valine instead of glutamic acid in the sixth position
8) The primary structure of a protein is determined by ________.
A) the sequence of amino acids
B) hydrogen bonds formed between the components of the peptide linkage
C) a series of helical domains
D) pleated sheets
E) covalent bonds formed between fibroin residues
A) the sequence of amino acids
9) Which protein class directly controls many of the metabolic reactions within a cell? A) structural proteins B) repressor proteins C) operator proteins D) enzymes E) hydrophilic proteins
D) enzymes
10) The secondary structure of a protein includes \_\_\_\_\_\_\_\_. A) gamma and delta B) alpha and gamma C) α-helix and β-pleated sheet D) hydrophobic clusters E) disulfide bridges
C) α-helix and β-pleated sheet
11) Side groups of amino acids are typically classified under which of the following? A) polar, nonpolar B) linear, circular C) alpha, omega D) long, short E) primary, secondary
A) polar, nonpolar
12) Describe each of the following parameters that relate to the structure and function of tRNA:
(a) four functional domains
(a) The four functional domains are amino acid attachment site, ribosome binding site, anticodon, and aminoacyl synthetase binding site.
12) Describe each of the following parameters that relate to the structure and function of tRNA:
(b) Wobble hypothesis
(b) The Wobble hypothesis states that the first two positions of the codon are precise in their complementary relationships. However, the third position is less specific.
13) Assume that a base addition occurs early in the coding region of a gene. Is the protein product of this gene expected to have more or fewer altered amino acids compared with the original gene with a base deletion late in the coding region?
More
14) During translation, which triplets signal chain termination?
UAA, UGA, UAG
17) Knowing that the base sequence of any given messenger RNA is responsible for precisely ordering the amino acids in a respective protein, present two mechanisms by which intrinsic properties of mRNA may regulate the “net output” of a given gene.
(a) Final output of a given gene may be influenced by the stability of an mRNA, and stability of an mRNA is determined in part by its base content and sequence. (b) Differential splicing of mRNA (actually mRNA precursors) can influence how much of a given product will be made from a gene.
18) Three major types of RNAs are mRNA, rRNA, and tRNA. For each of the conditions below, predict the consequences in terms of the population of proteins being synthesized in a particular cell. What qualitative and quantitative changes, if any, are expected in the individual protein involved (if one is involved) and in the population of proteins in this cell?
(a) Population of proteins: Half of the protein products of that gene will be defective, and the other half will be normal. Individual protein: The protein should show multiple amino acid substitutions “downstream” from the point of the mutation. If a nonsense triplet is introduced, the protein will be shortened in the substituted region.
(b) Population of proteins: There would be an overall reduction in protein synthesis. Individual proteins: All of the proteins would be made in their normal form but at reduced levels.
