Practice Multiple-Choice Questions on Genetics Chapters 16-201) For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. This is because A) proteins have a greater variety of three-dimensional forms than does DNA. B) proteins have two different levels of structural organization; DNA has four. C) proteins are made of 20 amino acids and DNA is made of four nucleotides. D) Only A and C are correct. E) A, B, and C are correct. 2) What does transformation involve in bacteria? A) the creation of a strand of DNA from an RNA molecule B) the creation of a strand of RNA from a DNA molecule C) the infection of cells by a phage DNA molecule D) the type of semiconservative replication shown by DNA E) assimilation of external DNA into a cell 3) In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? A) DNA does not contain sulfur, whereas protein does. B) DNA contains phosphorus, but protein does not. C) DNA contains nitrogen, whereas protein does not. D) A and B only E) A, B, and C 4) Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately, what percentage of the nucleotides in this sample will be thymine? A) 12 B) 24 C) 31 D) 38 E) It cannot be determined from the information provided. 5) All of the following can be determined directly from X-ray diffraction photographs of crystallized DNA except the A) diameter of the helix. B) helical shape of DNA. C) sequence of nucleotides. D) spacing of the nitrogenous bases along the helix. E) number of strands in a helix. 6) The DNA double helix has a uniform diameter because ________, which have two rings, always pair with ________, which have one ring. A) purines; pyrimidines B) pyrimidines; purines C) deoxyribose sugars; ribose sugars D) ribose sugars; deoxyribose sugars E) nucleotides; nucleoside triphosphates7) What kind of chemical bond is found between paired bases of the DNA double helix? A) hydrogen B) ionic C) covalent D) sulfhydryl E) phosphate 8) The strands that make up DNA are antiparallel. This means that A) the twisting nature of DNA creates nonparallel strands. B) the 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. C) base pairings create unequal spacing between the two DNA strands. D) one strand is positively charged and the other is negatively charged. E) one strand contains only purines and the other contains only pyrimidines. 9) Which enzyme catalyzes the elongation of a DNA strand in the 5' 3' direction? A) primase B) DNA ligase C) DNA polymerase D) topoisomerase E) helicase 10) The leading and the lagging strands differ in that A) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. B) the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. C) the leading strand is synthesized continuously, whereas the lagging strand is synthesized in short fragments that are ultimately stitched together. D) both A and B E) both A and C 11) E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment? A) one high-density and one low-density band B) one intermediate-density band C) one high-density and one intermediate-density band D) one low-density and one intermediate-density band E) one low-density band 12) All of the following are functions of DNA polymerase in DNA replication except A) covalently adding nucleotides to the new strands. B) proofreading each added nucleotide for correct base pairing. C) replacing RNA primers with DNA. D) initiating a polynucleotide strand. E) none of the above 13) Which of the following represents a similarity between RNA and DNA? A) Both are double-stranded. B) the presence of uracil C) the presence of an OH group on the 2' carbon of the sugarD) nucleotides consisting of a phosphate, sugar, and nitrogenous base E) Both are found exclusively in the nucleus. 14) The nitrogenous base adenine is found in all members of which group? A) proteins, triglycerides, and testosterone B) proteins, ATP, and DNA C) ATP, RNA, and DNA D) alpha glucose, ATP, and DNA E) proteins, carbohydrates, and ATP 15) If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides? A) 1 B) 2 C) 3 D) 4 E) 12 16) A codon A) consists of two nucleotides. B) may code for the same amino acid as another codon. C) consists of discrete amino acid regions. D) catalyzes RNA synthesis. E) is found in all eukaryotes, but not in prokaryotes. 17) If the triplet CCC codes for the amino acid proline in bacteria, then in plants CCC should code for A) leucine. B) valine. C) cystine. D) phenylalanine. E) proline. 18) Which of the following are transcribed from DNA? A) protein B) exons C) rRNA D) B and C only E) A, B, and C 19) Which of the following is not a part of the eukaryotic transcription initiation complex? A) promoter B) RNA polymerase C) transcription factors D) snRNP E) TATA box 20) All of the following are found in prokaryotic mRNA except A) the AUG codon. B) the UGA codon. C) introns.D) uracil. E) cytosine. 21) Alternative RNA splicing A) is a mechanism for increasing the rate of transcription. B) can allow the production of proteins of dramatically different sizes from a single mRNA. C) can allow the production of proteins of dramatically different amino acid sequences from a single mRNA. D) B and C only E) A, B, and C 22) Where is eukaryotic ribosomal RNA transcribed? A) the Golgi apparatus B) ribosomes C) the nucleolus D) X chromosomes E) prokaryotic cells only 23) During translation, chain elongation continues until what happens? A) No further amino acids are needed by the cell. B) All tRNAs are empty. C) The polypeptide is long enough. D) A stop codon is encountered. E) The ribosomes run off the end of mRNA. 24) What is one function of a signal peptide? A) to