Bio 286 Exam 1 Test

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BIOL 286 Exam I September 27, 2023 Personal Information on the answer sheet -Enter your CUNY ID in the boxes fill in corresponding circles --Print your First and Last name in the box near the bottom -Sign your name somewhere near your printed name Test answers on the answer sheet, fill in the BEST possible answer. 01. Hydrocarbons are NOT soluble in water because a. they are hydrophilic. b. the C- H bond is nonpolar. c. they do not ionize. d. they are large molecules. e. they are lighter than water. 02. A nucleic acid is a. a polynucleotide. b. hydrophobic. c. linked to an amino acid via a peptide bond. d. a form of energy storage in the cell. e. linked to other nucleic acids by covalent bonds between bases. 03. Which of the following is NOT a macromolecule formed by polymerization? a. polypeptide b. lipids c. nucleic acid d. polysaccharides e. DNA 04. The backbone of a DNA molecule is a. made up of sugars. b. made up of nitrogenous bases. c. made up of phosphate groups. d. made up of alternating phosphate and sugar groups. e. made up of alternating sugars and nitrogenous bases. 05. Muscle cells differ from nerve cells mainly because they a. have different chromosomes. b. contain different genes. c. use different genetic codes. d. have unique ribosomes. e. express different genes. 06. Lipids form the barriers surrounding various compartments within an organism. Which property of lipids makes them a good barrier? a. Many biologically important molecules are not soluble in lipids. b. Lipids are polymers. c. Lipids store energy.

d. Triglycerides are lipids. e. Lipids release large amounts of energy when broken down. 07. Interactions between amino acid R-groups are important in determining both the tertiary and______ structure of a protein. a. primary, secondary b. secondary, tertiary c. tertiary, quaternary d. primary, tertiary e. secondary, quaternary 08. Nucleotides are joined together in a single strand of DNA by a. hydrogen bonds. b. carbon-carbon bonds. c. hydrophobic interactions. d. glycosidic linkages. e. phosphodiester bonds. 09. As described in class, during transcription of a certain gene, the RNA polymerase will transcribe a. both strands, but only one RNA molecule will be used. b. only one of the DNA strands, moving in a 3' to 5' direction along the template. c. both strands, but moving 3' to 5' for one and 5' to 3' along the other. d. only the exons of the gene while skipping over the introns. e. Both b and d are correct answers. 10. Which of the following is attached covalently to a transfer RNA (tRNA)? a. DNA b. ribosome c. amino acid d. GTP e. mRNA 11. What lies between the methylguanosine cap at the start of a mRNA and extends to the AUG initiation codon? a. the first intron b. the last exon c. the 5' UTR d. the 3' UTR e. the last intron 12. Which of the following would be expected as the result of polymerization reactions in which four monomers are linked to form a straight chain polymer? a. Energy is released and four water molecules are produced. b. Energy is consumed and four water molecules are consumed. c. Energy is released and three water molecules are produced. d. Energy is consumed and three water molecules are produced. e. Energy is released and three water molecules are consumed.

13. Which experimental approach would provide the most information about differences in membrane fluidity between two types of cells? a. Measuring the sizes of the two types of cells b. Measuring the rate of protein uptake from outside of the cell c. Measuring the glycoprotein content of the two cells d. Measuring the ratio of saturated to unsaturated fatty acids in the cells e. Measuring the rate of vesicle formation during exocytosis 14. Which statement correctly describes a difference between DNA and RNA? a. DNA is single-stranded, whereas RNA is double-stranded. b. DNA occurs in the nucleus, whereas RNA only occurs outside the nucleus. c. DNA contains a ribose, whereas RNA contains a deoxyribose. d. DNA is replicated, whereas RNA is translated. e. DNA contains four nucleotides, whereas RNA contains three 15. A company has developed a detergent that disrupts biological membranes by mimicking the structure of their phospholipids. It is most likely that the active ingredient a. is a large non-polar lipid that binds the polar "heads" of the phospholipid bilayer, neutralizing their charge and attraction to one another. b. as a long polar "tail" that inserts into the hydrophobic core of the phospholipid bilayer, preventing stacking of the fatty acids. c. has both a polar end and a non-polar end that inserts into the membrane, disturbing the interaction between existing phospholipids. d. has a highly charged polar "head" that binds to membrane phospholipids, causing them to flip their orientation and scatter in the aqueous environment. e. is composed of a chain of carbohydrates that inserts into the hydrophilic core of the membrane, preventing stacking between other phospholipids. 16. Which DNA base pair is represented in the figure? a. A-T b. T-A c. G-C d. C-G 17. You have a piece of DNA that includes the following sequence: 5 ' -ATAGGCATTCGATCCGGATAGCAT-3' 3' -TATCCGTAAGCTAGGCCTATCGTA-5' Which of the following RNA molecules could be transcribed from this piece of DNA if the TOP strand is the template strand? a. 5'-UAUCCGUAAGCUAGGCCUAUGCUA-3' b. 5'-AUAGGCAUUCGAUCCGGAUAGCAU-3' c. 5'-UACGAUAGGCCUAGCUUACGGAUA-3' d. 5'-AUGCUAUCCGGAUCGAAUGCCUAU-3' e. None of the other answers are correct.

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18. This figure shows a compound that is soluble in chloroform, a nonpolar organic solvent, but it is not soluble in water. Based on this information, to which class of biological macromolecules does this compound belong? a. Oligosaccharides b. Carbohydrates c. Proteins d. Enzymes e. Lipids 19. Olive oil melts at a lower temperature than beef fat because a. oils contain glycerol, whereas fats do not. b. fats contain more saturated fatty acids than oils do. c. fats contain more unsaturated fatty acids than oils do. d. oils are made by plants, whereas fats are made by animals. e. olive trees naturally occur in warmer climates than beef cattle do. 20. Which of the following statements is true for the two genes that are next to each other on a chromosome, as arranged in the figure below? a. The two genes must be transcribed into RNA using the same strand of DNA. b. If gene A is transcribed in a cell, gene B cannot be transcribed. c. Gene A and gene B can be transcribed at different rates, producing different amounts of RNA within the same cell. d. If gene A is transcribed in a cell, gene B must be transcribed. e. None of the other answers is correct. 21. The greatest similarities among codons specifying the same amino acid occur a. in the first two nucleotides of the triplet. b. in the last two nucleotides of the triplet. c. in the first and third nucleotides of the triplet. d. in the third nucleotide of the triplet. e. in the middle nucleotide of the triplet. 22. In some cases, a single amino acid substitution can cause a protein to lose its biological activity. In other cases, a single amino acid substitution causes no change to a protein's biological activity. Which statement can best be used as evidence to support an explanation for these observations? a. Amino acids are covalently linked through peptide bonds to form the primary structure of a protein. b. Amino acids found in the proteins of living organisms have many similarities, including an alpha-amino group and an alpha-carboxyl group. c. Amino acids occur as optical isomers, but only one isomer of each is found in the proteins of most of the organisms on Earth.

d. Noncovalent interactions between atoms in a polypeptide chain stabilize the secondary, tertiary, and quaternary levels of its structure. e. Each amino acid side chain has properties that are very different from those of some side chains and very similar to those of others. 23. Within a polypeptide chain is the following amino acid sequence, which reads in the N terminus to C terminus direction from left to right: Glycine-Tyrosine-Serine. Which statement about this polypeptide is true? a. A hydrolysis reaction occurred during peptide bond formation between the carboxyl group of glycine and the carboxyl group of tyrosine. b. A condensation reaction formed a peptide bond between the amino group of glycine and the carboxyl group of tyrosine. c. A molecule of water was released when the carboxyl group of tyrosine formed a peptide bond with the amino group of serine. d. The side chains or R groups of the amino acids in the sequence are covalently bonded to one another through peptide bonds. e. The polypeptide can become branched if the side chain of tyrosine reacts with a free amino acid to form a peptide bond. 24. The number of distinctive protein species found in many eukaryotes can be much greater than the number of genes. This is predominantly due to a. protein degradation. b. alternative splicing. c. homologous genes. d. mutation in exon regions. e. mutation in a regulatory region. 25. The family of proteins that help other proteins fold correctly is called a. foldzymes. b. renaturing proteins. c. chaperones. d. deubiquitinases. e. denaturing proteins. 26. DNA has a net (overall)______ charge due to its component _______ . a. negative, deoxyribose b. positive, ribose c. negative, phosphate groups d. negative, chlorine ions e. positive, adenine 27. In eukaryotes, ________helps the selection of the correct tRNA at the A site on the ribosome. a. peptidyltransferase b. aminoacyl-tRNA synthetase c. elF2 d. eEFl ⍺ e. ATP synthase 28. In which of the following would you find phosphodiester bonds?

a. cholesterol b. glycogen c. hemoglobin d. snRNA e. Lactose 29. Many genes are activated by adding___to the tail of____ to loosen the chromatin complex allowing RNA polymerase access and thus transcription. a. phosphates, histones b. acetyl groups, histones c. methyl groups, nucleotides d. phosphates, nucleotides e. acetyl groups, nucleotides 30. The expression of the genes in the bacterial tryptophan operon a. is promoted by the binding of tryptophan to the RNA polymerase. b. is inhibited by the binding of tryptophan to the RNA polymerase. c. is promoted by tryptophan binding to an activator. d. is inhibited by tryptophan binding to a repressor. e. is promoted by tryptophan degradation products. 31. In an a helix, hydrogen bonds form between: a. acidic and basic amino acid side chains. b. every fourth amino acid. c. every other amino acid. d. nonpolar amino acid side chains. e. the peptide bonds and DNA. 32. In eukaryotes the initiating AUG is distinguished from subsequent internal AUGs in part by a. TATA boxes. b. promoter sequences. c. zinc fingers. d. homeodomains. e. Kozak sequences. 33. Of the 64 possible codons, how many do NOT code for amino acids? a. 20 b. 61 c. 0 d. 3 e. 21 34. If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then the a. enzymes produced are called inducible enzymes. b. amino acid activates the repressor. c. amino acid inactivates the repressor. d. amino acid turns on transcription of the operon. e. repressor is active in the absence of the amino acid.

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35. Which of the following statements about the DNA and one of your brain cells is true? a. each gene lies immediately adjacent to an enhancer. b. it is the same as the DNA in one of your heart cells. c. most of the genes are likely to be transcribed d. most of the DNA encodes for protein. e. many genes are grouped into operon like clusters 36. You add a reagent that breaks bonds between sulfur atoms to a partially purified preparation of protein. Which level(s) of protein structure are likely to be affected? a. Tertiary b. Secondary c. Primary d. Quaternary e. Both tertiary and quaternary will be affected. 37. _____ are macromolecular complexes that bind to hnNA and function to remove introns. a. Splicers b. Introverts c. Spliceosomes d. Splicing bodies e. Splice engines 38. What is the function of TFIIH in the transcription initiation complex? a. binding to the TATA box. b. unwinding the DNA duplex. c. catalyzing the synthesis of RNA. d. phosphorylate the TBP. e. Both b and dare correct answers. 39. Which of the following statements best describes the term "protein domain." a. a small cluster of a helices and 3 sheets b. the tertiary structure of a substrate-binding pocket c. a complex of more than one polypeptide chain d. a protein segment that folds independently e. a protein segment corresponding to introns in the gene 40. Amino acids are attached to their tRNA molecules by a. aminoacyl hydroxylases. b. aminoacyl-tRNA synthetases. c. hydrogen bonds. d. peptide bonds. e. RNA ligase. 41. Polypeptides are synthesized from amino acid building blocks. The reaction between the growing polypeptide chain and the next amino acid to be added involves the loss of a. a water molecule. b. an amino group. c. a carbon atom. d. a carboxylic acid group.

e. O ₂ 42. Within a cell, the amount of protein made using a given mRNA molecule depends partly on a. the degree of histone acetylation. b. the types of ribosomes present in the cytoplasm. c. the number of introns present in the mRNA d. the rate at which mRNA is degraded. e. the presence of certain transcription factors. 43. Of the following steps associated with translation, which does NOT involve hydrolysis of GTP? a. release of polypeptide from ribosome b. formation of the initiation complex c. aminoacylation of tRNA d. translocation of the ribosome e. binding of the aminoacyl tRNA to codon at the A site 44. Cellular protein synthesis proceeds in which direction? a. carboxyl to amino terminus b. amino to carboxyl terminus c. 3' to 5' d. 5' to 3' e. Either answer a or b can be correct depending on the location of the promoter relative to the encoding region of the gene. 45. Which process requires the participation of all three major types of RNA? a. transcription b. translation c. RNA processing d. replication e. Splicing 46. During polypeptide elongation, the associated ribosome is bound to appropriate tRNAs in both the A and the P sites and is ready for peptidyl transfer. What happens next? a. The carboxyl end of the polypeptide chain is released from the P-site tRNA and joined to the free amino group of the amino acid linked to the A-site tRNA. b. The amino end of the polypeptide chain is released from the P-site tRNA and joined to the free carboxyl group of the amino acid linked to the A-site tRNA. c. The carboxyl end of the amino acid is released from the A-site tRNA and joined to the free amino group of the polypeptide chain linked to the P-site tRNA. d. The amino end of the amino acid is released from the A-site tRNA and joined to the free carboxyl group of the polypeptide chain linked to the P-site tRNA. e. Depending on the identity of the polypeptide either c or d could be a correct answer. 47. Which of the following statements about amino acids is TRUE? a. Twenty-two amino acids are commonly found in proteins. b. Amino acids are synthesized on ribosomes. c. Most of the amino acids used in protein biosynthesis have charged side chains (R groups). d. Amino acids are often linked together to form branched polymers. e. All amino acids contain an NH, and a COOH group.

48. The 3' end of most eukaryotic mRNAs contains a ____, while the 5' end has a ______ . a. poly(A) tail, methylated guanosine cap b. poly (U) tail, methylated guanosine cap c. methylated guanosine cap, poly(A) tail d. poly(A) tail, sulfonated guanosine cap e. methylated guanosine cap, poly(U) tail 49. DNA has a overall ____ charge due to its component ______ . a. negative, deoxyribose b. positive, ribose c. negative, phosphate groups d. negative, chlorine ions e. positive, adenine 50. What is a characteristic of amino acids found in an a-helical segment of a protein that spans a membrane? a. circular b. hydrophilic c. hydrophobic d. antiparallel e. parallel The following three questions are extra-credit questions. Guessing the answers cannot hurt your score. Your test score will be determined as the number of correct answers on this test divided by 50. If you answer all three questions correctly, and the other 50 questions also correctly, your score will be 53/50= 106%. If you answer all bonus questions incorrectly, but answer the other 50 correctly, your grade on this test will be 50/50=100%. 51. Scientists can manipulate cells so that certain proteins can emit a green light. When a protein, which functions in ribosomes, was made green the scientists observed green fluorescence in the cytosol and in the nucleus. This is probably because a. the ribosomal protein was being translated in the nucleus and moved to the cytosol to function. b. the ribosomal protein was synthesized in the cytosol and moved to the nucleus to form a ribosome. c. the ribosomal protein moved into the nucleus for degradation. d. There should be no nuclear fluorescence; it was an experimental error. e. Both a and c are correct answers. 52. Which of the following molecules of RNA would you predict to be the most likely to fold into a specific structure because of intramolecular (within the same molecule) base-pairing? a. 5'-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3' b. 5'-UGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUG-3' c. 5'-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-3' d. 5'-GGAAAAGGAGAUGGGCAAGGGGAAAAGGAGAUGGGCAAGG-3' e. 5'-UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU-3' 53. Scientists have identified a Drosophila (fruit fly) mutant that grows an eye on its wing. They found that this mutant strain of Drosophila expresses a specific transcription factor incorrectly. In the mutant Drosophila, this transcription factor, which is normally expressed in the eye, is now missexpressed in the wing, thus turning on transcription of the set of genes required to

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produce an eye in wing tissue. If this hypothesis were true, which of the following types of genetic change would most likely lead to this situation? a. A mutation within the transcription factor gene that leads to a premature stop codon after the fourth amino acid. b. A mutation within the transcription factor gene that leads to a substitution of a positively charged amino acid for a negatively charged amino acid. c. A mutation within an upstream enhancer (DNA binding site for specific transcription factors) of the gene. d. A mutation in the TATA box of the gene. e. A mutation in the first intron of the gene.

Bio 286 Exam 1 Test

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