1 TAKE HOME EXAM FOR THE MOLECULAR GENETICS REVIEW BIOL 110 To understand microbiology, it is essential to have a fairly good understanding of such basic points of molecular genetics (proteins, enzymes, DNA, RNA, transcription, translation, and mutation. The purpose of this take home exam is to enable you – or force you if you prefer – to review these topics that you learned in your prerequisite course, BIOL 110. It will also introduce you to mechanisms of genetic recombination in bacteria. Read the Review of Molecular Genetics for Take Home Exam included in your hard copy of my Lecture Guide. It can be found at the end of Part-1 of my BIOL 230 Lecture E-text following the Unit 3 segment. I would urge you to use the hard copy of this material in conjunction with the illustrations and animations in the online version found on my web page at http://faculty.ccbcmd.edu/courses/bio141/lecguide/takehome/index.html After you read these sections and study the illustrations and animations, answer the enclosed Take Home Exam. OBJECTIVES FOR TAKE HOME EXAM FOR THE MOLECULAR GENETICS (DO NOT ANSWER THESE.) While you don’t have to turn in the Objectives listed below, these are objectives I would expect you to be fairly fluent with before we get very far into this course. (This is the major reason why BIOL 110 is a prerequisite for Microbiology.) If you answer the objectives first, you will find it easier to answer the take home exam. I. MICROBIAL GENETICS A. Polypeptides, Proteins, and Enzymes 1. Define or describe the following: a. amino acid b. “R” group c. peptide bond d. peptide e. polypeptide f. primary protein structure g. secondary protein structure h. tertiary protein structure i. quaternary protein structure j. gene 2. Describe how the primary structure of a protein or polypeptide ultimately detemines its final three-dimensional shape. 3. Describe how the order of nucleotide bases in DNA ultimately determines the final three-dimensional shape of a protein or polypeptide. B. Deoxyribonucleic Acid 1. State the 3 basic parts of a deoxyribonucleotide. 2. State which nitrogenous bases are purines and which are pyrimidines. 3. Define complementary base pairing. 2 C. DNA Replication 1. Briefly describe the process of DNA replication in bacteria. D. Ribonucleic Acid 1. State the 3 basic parts of a ribonucleotide. 2. State 3 ways RNA differs from DNA. 3. State the function of each of the following: a. tRNA b. mRNA c. rRNA E. Polypeptide and Protein Synthes 1. Define the following: a. gene b. transcription c. translation 2. Briefly describe the function of the following in terms of bacterial protein synthesis: a. mRNA b. RNA polymerase c. promoter region d. codon e. 30S ribosomal subunit f. 50S ribosomal subunit g. tRNA h. anticodon i. P-site of ribosome j. A-site of ribosome k. peptidyl transferase l. nonsense (stop) codon 3. Describe how the order of nucleotide bases along a gene in the DNA ultimately determines the three dimensional shape of the protein coded for by that gene. F. Mutation 1. Define mutation and genetic recombination. 2. Describe 2 different mechanisms of mutation and, in terms of protein synthesis, describe the 4 possible results that may occur as a result of these mutations. G. Genetic Recombination in Bacteria 1. Briefly describe the following means of genetic recombination in bacteria: a. transformation b. transduction c. conjugation 3 BIOL 230 MICROBIOLOGY TAKE HOME EXAM FOR THE MOLECULAR GENETICS REVIEW Name: Lab Section: 60 points 1. Matching _____ The molecule synthesized by complementary base pairing of RNA nucleotides with DNA nucleotides to match a portion of one strand of DNA coding for a protein or polypeptide. _____ The enzymes that initiate and terminate transcription as well as join RNA nucleotides together. _____ A specific nucleotide sequence at the beginning of a gene to which RNA polymerase binds to start transcription. _____ A series of 3 consecutive mRNA bases coding for one specific amino acid. _____ The molecules that picks up specific amino acids and carries those amino acids to the ribosomes during translation. _____ A series of 3 tRNA bases complementary to a specific codon. _____ The site on a 50S ribosomal subunit to which new charged tRNA molecules first attach. _____ A series of 3 mRNA bases coding for no amino acid; serves as a signal to terminate translation. _____ The molecules that, along with proteins, form ribosomes. A. anticodon G. “P” site of ribosome B. “A” site of ribosome H. promoter region C. codon I. rRNA D. DNA polymerase J. RNA polymerases E. mRNA K. tRNA F. nonsense (stop) codon 4 2. Matching _____ The order of amino acids in a protein. _____ The folded, three-dimensional, functional shape of a protein. _____ Metabolic reactions in which molecules are broken down. _____ The sequence of purine and pyrimidine bases on one strand of DNA that codes for the amino acid sequence of a particular protein or polypeptide. _____ The process wherein mRNA is synthesized to be complementary to a gene. _____ The process wherein tRNA carries specific amino acids to the ribosomes and inserts them in proper place according to the mRNA “message.” A. gene F. anabolic reactions B. nucleotide G. catabolic reactions C. primary protein structure H. transcription D. secondary protein structure I. transformation E. tertiary protein structure J. translation 3. _____ The nitrogenous bases cytosine and thymine are: A. purines B. codons C. proteins D. complementary to each other E. pyrimidines 4. _____ Complementary base pairing is the hydrogen bonding of: A. adenine with thymine; cytosine with guanine B. adenine with guanine; thymine with cytosine C. adenine with cytosine; guanine with uracil D. adenine with guanine; thymine with uracil E. Mo with Larry; Curly with Sven the Wonder Llama 5. _____ Which does NOT describe transcription? A. RNA polymerase B. mRNA synthesis occurs C. tRNA carries amino acids to the ribosomes D. copying of a portion of one strand of DNA E. complementary base pairing 6. _____ In RNA, uracil hydrogen bands with: A. guanine B. cytosine C. thymine D. adenine E. Throckmorton the Mediocre Moose (whose second cousin, by coincidence, is Sven the Wonder Llama) 5 7. _____ Which does NOT describe an R-plasmid? A. usually has genes for coding for a sex pilus B. has genes for multiple antibiotic resistance C. usually allows for conjugation D. found in many gram-negative bacteria E. carried from one bacterium to another by temperate phages 8. _____ Which describes a DNA nucleotide? A. 1 nitrogenous base, 1 phosphate, 1 ribose B. 1 nitrogenous base, 1 protein, 1 ATP C. 1 deoxyribose, 1 codon, 1 phosphate D. 1 nitrogenous base, 1 deoxyribose, 1 phosphate E. faster than a speeding bullet, more powerful than a locomotive, able to leap a Wonder Llama, eg, Sven, in a single bound 9. _____In the primary structure of a protein, the amino acids are connected to one another by: A. hydrogen bonds B. disulfide bonds C. congealed Yoo Hoo brand chocolate drink D. RNA E. peptide bonds 10. _____ ______________ molecules of tRNA with one or more attached amino acids can bind to a single ribosome at one time. A. one B. two C. three D. four E. 376,251,134.628, + or – pi (which, by one of those strange quirks of fate, just happens to be the telephone number of Olga, booking agent and personal manager to Sven, the Wonderous Wonder Llama – not available for birthdays) 11. _____ During protein synthesis, the proper amino acid is put in the proper place according to the genetic message by: A. transcription B. an anticodon hydrogen bonding with a codon C. RNA polymerase D. a nonsense codon E. bet you thought I was going to say “Sven” of Wonder Llama fame 12. _____ The sequence of _________________ in a DNA molecule ultimately determines the order of amino acids in proteins. A. deoxyribose molecules B. purine and pyrimidine bases C. phosphates D. anticodons E. plasmids 6 13. _____ Addition and deletion mutations usually result in: A. one wrong amino acid in protein B. what happens when the dental technician X-rays your teeth after always leaving the room and giving you flimsy excuses for doing so like “I have to go put my socks in the dryer” or “I think my Wonder Llama just threw up a hairball” C. a reading frame shift D. one wrong codon in the DNA E. substitution of one base in the DNA 14. _____A tRNA with an ACC anticodon will hydrogen bond with a ______ mRNA codon. (Use your codon sheet, Fig. 8 in the transcription section; Fig. 2 in the translation section.) A. TGG B. UGG C. ACC D. UCC E. stop 15. _____ A tRNA with an ACC anticodon will insert the amino acid ________ during translation. (Use your codon sheet, Fig. 8 in the transcription section; Fig. 2 in the translation section.) A. Cys B. Ser C. Trp D. Arg E. Svn DISCUSSION 1. Briefly DESCRIBE THE FUNCTION of the following in terms of bacterial protein synthesis: (2 points each) A. mRNA B. codon C. tRNA D. anticodon E. nonsense codon 7 2. As a result of a substitution mutation, a DNA base triplet 3’ ATA 5’ is charged to 3’ ATT 5’. State specifically what effect this would have on the resulting protein. (Use your codon sheet, Fig. 8 in the transcription section; Fig. 2 in the translation section.) (4 points) 3. Describe 2 different mechanisms of mutation and, in terms of protein synthesis, describe the 4 possible results that may occur as a result of these mechanisms. (7 points) 4. DESCRIBE how the order of nucleotide bases along a gene in the DNA ultimately determines the threedimensional shape and function of the protein coded for by that gene. (5 points) 5. Describe R-plasmid conjugation and its significance to medical microbiology. (3 points) 6. Compare transformation and transduction in bacteria. (2 points)